Add PostgreSQL FOR UPDATE getters

Add a PostgreSQL-specific getRecordForUpdate helper that appends FOR UPDATE to the generated SELECT statement so callers can lock a row inside an explicit transaction. generateProcsForModels now always emits a direct-connection get<RecordName>ForUpdate proc that accepts db_postgres.DbConn. There is intentionally no dbType overload for this API, because reacquiring a connection via withConnection would defeat the lock's transactional scope. The source docs and README now document the new helper and show the intended usage pattern inside inTransaction: db.inTransaction: var item = conn.getTodoItemForUpdate(todoId) item.priority += 1 discard conn.updateTodoItem(item)
Update documentation for new signature changes, bump version.
2026-03-24 22:04:49 -05:00 · 2026-03-24 21:48:51 -05:00 · 2026-03-24 21:39:25 -05:00 · 2025-09-02 00:40:00 -05:00 · 2025-09-02 00:36:11 -05:00 · 2025-07-27 17:47:07 -05:00
7 changed files with 677 additions and 191 deletions
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,4 @@
 *.sw?
 nimcache/
+nimble.develop
+nimble.paths
--- a/README.rst
+++ b/README.rst
@@ -83,7 +83,7 @@ Using Fiber ORM we can generate a data access layer with:
 .. code-block:: Nim
   # db.nim
   import std/[options]
-   import db_connectors/db_postgres
+   import db_connector/db_postgres
   import fiber_orm
   import ./models.nim

@@ -100,32 +100,90 @@ Using Fiber ORM we can generate a data access layer with:

   generateLookup(TodoDB, TimeEntry, @["todoItemId"])

-This will generate the following procedures:
+This will generate procedures like the following in two flavors:
+
+* a `dbType` flavor that acquires a connection via `withConnection`
+* a connection flavor that operates directly on an existing
+  `conn: D` where `D: DbConnType`

 .. code-block:: Nim
   proc getTodoItem*(db: TodoDB, id: UUID): TodoItem;
+   proc getTodoItem*[D: DbConnType](conn: D, id: UUID): TodoItem;
+   proc getTodoItemForUpdate*(conn: db_postgres.DbConn, id: UUID): TodoItem;
+   proc tryGetTodoItem*(db: TodoDB, id: UUID): Option[TodoItem];
+   proc tryGetTodoItem*[D: DbConnType](conn: D, id: UUID): Option[TodoItem];
   proc getTodoItemIfItExists*(db: TodoDB, id: UUID): Option[TodoItem];
-   proc getAllTodoItems*(db: TodoDB): seq[TodoItem];
+   proc getTodoItemIfItExists*[D: DbConnType](
+     conn: D, id: UUID): Option[TodoItem];
+   proc getAllTodoItems*(db: TodoDB,
+     pagination = none[PaginationParams]()): PagedRecords[TodoItem];
+   proc getAllTodoItems*[D: DbConnType](conn: D,
+     pagination = none[PaginationParams]()): PagedRecords[TodoItem];
   proc createTodoItem*(db: TodoDB, rec: TodoItem): TodoItem;
+   proc createTodoItem*[D: DbConnType](conn: D, rec: TodoItem): TodoItem;
   proc updateTodoItem*(db: TodoDB, rec: TodoItem): bool;
+   proc updateTodoItem*[D: DbConnType](conn: D, rec: TodoItem): bool;
+   proc createOrUpdateTodoItem*(db: TodoDB, rec: TodoItem): TodoItem;
+   proc createOrUpdateTodoItem*[D: DbConnType](
+     conn: D, rec: TodoItem): TodoItem;
   proc deleteTodoItem*(db: TodoDB, rec: TodoItem): bool;
+   proc deleteTodoItem*[D: DbConnType](conn: D, rec: TodoItem): bool;
   proc deleteTodoItem*(db: TodoDB, id: UUID): bool;
+   proc deleteTodoItem*[D: DbConnType](conn: D, id: UUID): bool;

   proc findTodoItemsWhere*(db: TodoDB, whereClause: string,
-     values: varargs[string, dbFormat]): seq[TodoItem];
+     values: varargs[string, dbFormat],
+     pagination = none[PaginationParams]()): PagedRecords[TodoItem];
+   proc findTodoItemsWhere*[D: DbConnType](conn: D, whereClause: string,
+     values: varargs[string, dbFormat],
+     pagination = none[PaginationParams]()): PagedRecords[TodoItem];

   proc getTimeEntry*(db: TodoDB, id: UUID): TimeEntry;
+   proc getTimeEntry*[D: DbConnType](conn: D, id: UUID): TimeEntry;
   proc getTimeEntryIfItExists*(db: TodoDB, id: UUID): Option[TimeEntry];
-   proc getAllTimeEntries*(db: TodoDB): seq[TimeEntry];
+   proc getTimeEntryIfItExists*[D: DbConnType](
+     conn: D, id: UUID): Option[TimeEntry];
+   proc getAllTimeEntries*(db: TodoDB,
+     pagination = none[PaginationParams]()): PagedRecords[TimeEntry];
+   proc getAllTimeEntries*[D: DbConnType](conn: D,
+     pagination = none[PaginationParams]()): PagedRecords[TimeEntry];
   proc createTimeEntry*(db: TodoDB, rec: TimeEntry): TimeEntry;
+   proc createTimeEntry*[D: DbConnType](conn: D, rec: TimeEntry): TimeEntry;
   proc updateTimeEntry*(db: TodoDB, rec: TimeEntry): bool;
+   proc updateTimeEntry*[D: DbConnType](conn: D, rec: TimeEntry): bool;
   proc deleteTimeEntry*(db: TodoDB, rec: TimeEntry): bool;
+   proc deleteTimeEntry*[D: DbConnType](conn: D, rec: TimeEntry): bool;
   proc deleteTimeEntry*(db: TodoDB, id: UUID): bool;
+   proc deleteTimeEntry*[D: DbConnType](conn: D, id: UUID): bool;

   proc findTimeEntriesWhere*(db: TodoDB, whereClause: string,
-     values: varargs[string, dbFormat]): seq[TimeEntry];
+     values: varargs[string, dbFormat],
+     pagination = none[PaginationParams]()): PagedRecords[TimeEntry];
+   proc findTimeEntriesWhere*[D: DbConnType](conn: D, whereClause: string,
+     values: varargs[string, dbFormat],
+     pagination = none[PaginationParams]()): PagedRecords[TimeEntry];

-   proc findTimeEntriesByTodoItemId(db: TodoDB, todoItemId: UUID): seq[TimeEntry];
+   proc findTimeEntriesByTodoItemId*(db: TodoDB, todoItemId: UUID,
+     pagination = none[PaginationParams]()): PagedRecords[TimeEntry];
+   proc findTimeEntriesByTodoItemId*[D: DbConnType](
+     conn: D, todoItemId: UUID,
+     pagination = none[PaginationParams]()): PagedRecords[TimeEntry];
+
+Use the `dbType` flavor when the caller does not already have a connection.
+Use the connection flavor inside `withConnection` or `inTransaction`.
+The generated `get<RecordName>ForUpdate` helper is PostgreSQL-specific and
+is only available for direct PostgreSQL connections.
+
+Warning: do not call the `dbType` flavor from inside `inTransaction`.
+Those overloads call `withConnection` and may acquire a different
+connection, causing the statements to execute outside the active
+transaction.
+
+.. code-block:: Nim
+   db.inTransaction:
+     var item = conn.getTodoItemForUpdate(todoId)
+     item.priority += 1
+     discard conn.updateTodoItem(item)

 Object-Relational Modeling
 ==========================
@@ -133,11 +191,11 @@ Object-Relational Modeling
 Model Class
 -----------

-Fiber ORM uses simple Nim `object`s and `ref object`s as model classes.
+Fiber ORM uses simple Nim objects and ref objects as model classes.
 Fiber ORM expects there to be one table for each model class.

 Name Mapping
-````````````
+^^^^^^^^^^^^
 Fiber ORM uses `snake_case` for database identifiers (column names, table
 names, etc.) and `camelCase` for Nim identifiers. We automatically convert
 model names to and from table names (`TodoItem` <-> `todo_items`), as well
@@ -168,7 +226,7 @@ procedures in the `fiber_orm/util`_ module for details.
 .. _util: fiber_orm/util.html

 ID Field
-````````
+^^^^^^^^

 Fiber ORM expects every model class to have a field named `id`, with a
 corresponding `id` column in the model table. This field must be either a
@@ -257,8 +315,10 @@ Many of the Fiber ORM macros expect a database object type to be passed.
 In the example above the `pool.DbConnPool`_ object is used as database
 object type (aliased as `TodoDB`). This is the intended usage pattern, but
 anything can be passed as the database object type so long as there is a
-defined `withConn` template that provides an injected `conn: DbConn` object
+defined `withConnection` template that provides an injected `conn: DbConn` object
 to the provided statement body.
+The generated connection-flavor procedures are intended to work directly
+with that `conn` value.

 For example, a valid database object implementation that opens a new
 connection for every request might look like this:
@@ -269,7 +329,7 @@ connection for every request might look like this:
   type TodoDB* = object
     connString: string

-   template withConn*(db: TodoDB, stmt: untyped): untyped =
+   template withConnection*(db: TodoDB, stmt: untyped): untyped =
     let conn {.inject.} = open("", "", "", db.connString)
     try: stmt
     finally: close(conn)
--- a/fiber_orm.nimble
+++ b/fiber_orm.nimble
@@ -1,6 +1,6 @@
 # Package

-version       = "3.1.0"
+version       = "4.2.0"
 author        = "Jonathan Bernard"
 description   = "Lightweight Postgres ORM for Nim."
 license       = "GPL-3.0"
@@ -11,4 +11,4 @@ srcDir        = "src"
 # Dependencies

 requires @["nim >= 1.4.0", "uuids"]
-requires "namespaced_logging >= 1.0.0"
+requires "namespaced_logging >= 2.0.2"
--- a/src/fiber_orm.nim
+++ b/src/fiber_orm.nim
@@ -100,39 +100,89 @@
 ##
 ##    generateLookup(TodoDB, TimeEntry, @["todoItemId"])
 ##
-## This will generate the following procedures:
+## This will generate procedures like the following in two flavors:
+##
+## * a `dbType` flavor that acquires a connection via `withConnection`
+## * a connection flavor that operates directly on an existing
+##   `conn: D` where `D: DbConnType`
 ##
 ## .. code-block:: Nim
 ##    proc getTodoItem*(db: TodoDB, id: UUID): TodoItem;
-##
+##    proc getTodoItem*[D: DbConnType](conn: D, id: UUID): TodoItem;
+##    proc getTodoItemForUpdate*(conn: db_postgres.DbConn, id: UUID): TodoItem;
+##    proc tryGetTodoItem*(db: TodoDB, id: UUID): Option[TodoItem];
+##    proc tryGetTodoItem*[D: DbConnType](conn: D, id: UUID): Option[TodoItem];
+##    proc getTodoItemIfItExists*(db: TodoDB, id: UUID): Option[TodoItem];
+##    proc getTodoItemIfItExists*[D: DbConnType](
+##      conn: D, id: UUID): Option[TodoItem];
 ##    proc createTodoItem*(db: TodoDB, rec: TodoItem): TodoItem;
+##    proc createTodoItem*[D: DbConnType](conn: D, rec: TodoItem): TodoItem;
 ##    proc updateTodoItem*(db: TodoDB, rec: TodoItem): bool;
-##    proc createOrUpdateTodoItem*(db: TodoDB, rec: TodoItem): bool;
+##    proc updateTodoItem*[D: DbConnType](conn: D, rec: TodoItem): bool;
+##    proc createOrUpdateTodoItem*(db: TodoDB, rec: TodoItem): TodoItem;
+##    proc createOrUpdateTodoItem*[D: DbConnType](
+##      conn: D, rec: TodoItem): TodoItem;
 ##    proc deleteTodoItem*(db: TodoDB, rec: TodoItem): bool;
+##    proc deleteTodoItem*[D: DbConnType](conn: D, rec: TodoItem): bool;
 ##    proc deleteTodoItem*(db: TodoDB, id: UUID): bool;
+##    proc deleteTodoItem*[D: DbConnType](conn: D, id: UUID): bool;
 ##
 ##    proc getAllTodoItems*(db: TodoDB,
-##      pagination = none[PaginationParams]()): seq[TodoItem];
+##      pagination = none[PaginationParams]()): PagedRecords[TodoItem];
+##    proc getAllTodoItems*[D: DbConnType](conn: D,
+##      pagination = none[PaginationParams]()): PagedRecords[TodoItem];
 ##
 ##    proc findTodoItemsWhere*(db: TodoDB, whereClause: string,
 ##      values: varargs[string, dbFormat], pagination = none[PaginationParams]()
-##      ): seq[TodoItem];
+##      ): PagedRecords[TodoItem];
+##    proc findTodoItemsWhere*[D: DbConnType](conn: D, whereClause: string,
+##      values: varargs[string, dbFormat], pagination = none[PaginationParams]()
+##      ): PagedRecords[TodoItem];
 ##
 ##    proc getTimeEntry*(db: TodoDB, id: UUID): TimeEntry;
+##    proc getTimeEntry*[D: DbConnType](conn: D, id: UUID): TimeEntry;
 ##    proc createTimeEntry*(db: TodoDB, rec: TimeEntry): TimeEntry;
+##    proc createTimeEntry*[D: DbConnType](conn: D, rec: TimeEntry): TimeEntry;
 ##    proc updateTimeEntry*(db: TodoDB, rec: TimeEntry): bool;
+##    proc updateTimeEntry*[D: DbConnType](conn: D, rec: TimeEntry): bool;
 ##    proc deleteTimeEntry*(db: TodoDB, rec: TimeEntry): bool;
+##    proc deleteTimeEntry*[D: DbConnType](conn: D, rec: TimeEntry): bool;
 ##    proc deleteTimeEntry*(db: TodoDB, id: UUID): bool;
+##    proc deleteTimeEntry*[D: DbConnType](conn: D, id: UUID): bool;
 ##
 ##    proc getAllTimeEntries*(db: TodoDB,
-##      pagination = none[PaginationParams]()): seq[TimeEntry];
+##      pagination = none[PaginationParams]()): PagedRecords[TimeEntry];
+##    proc getAllTimeEntries*[D: DbConnType](conn: D,
+##      pagination = none[PaginationParams]()): PagedRecords[TimeEntry];
 ##
 ##    proc findTimeEntriesWhere*(db: TodoDB, whereClause: string,
 ##      values: varargs[string, dbFormat], pagination = none[PaginationParams]()
-##      ): seq[TimeEntry];
+##      ): PagedRecords[TimeEntry];
+##    proc findTimeEntriesWhere*[D: DbConnType](conn: D, whereClause: string,
+##      values: varargs[string, dbFormat], pagination = none[PaginationParams]()
+##      ): PagedRecords[TimeEntry];
 ##
-##    proc findTimeEntriesByTodoItemId(db: TodoDB, todoItemId: UUID,
-##      pagination = none[PaginationParams]()): seq[TimeEntry];
+##    proc findTimeEntriesByTodoItemId*(db: TodoDB, todoItemId: UUID,
+##      pagination = none[PaginationParams]()): PagedRecords[TimeEntry];
+##    proc findTimeEntriesByTodoItemId*[D: DbConnType](
+##      conn: D, todoItemId: UUID,
+##      pagination = none[PaginationParams]()): PagedRecords[TimeEntry];
+##
+## Use the `dbType` flavor when the caller does not already have a connection.
+## Use the connection flavor inside `withConnection` or `inTransaction`.
+## The generated `get<RecordName>ForUpdate` helper is PostgreSQL-specific and
+## is only available for direct PostgreSQL connections.
+##
+## Warning: do not call the `dbType` flavor from inside `inTransaction`.
+## Those overloads call `withConnection` and may acquire a different
+## connection, causing the statements to execute outside the active
+## transaction.
+##
+## .. code-block:: Nim
+##    db.inTransaction:
+##      var item = conn.getTodoItemForUpdate(todoId)
+##      item.priority += 1
+##      discard conn.updateTodoItem(item)
 ##
 ## Object-Relational Modeling
 ## ==========================
@@ -140,11 +190,11 @@
 ## Model Class
 ## -----------
 ##
-## Fiber ORM uses simple Nim `object`s and `ref object`s as model classes.
+## Fiber ORM uses simple Nim objects and ref objects as model classes.
 ## Fiber ORM expects there to be one table for each model class.
 ##
 ## Name Mapping
-## ````````````
+## ^^^^^^^^^^^^
 ## Fiber ORM uses `snake_case` for database identifiers (column names, table
 ## names, etc.) and `camelCase` for Nim identifiers. We automatically convert
 ## model names to and from table names (`TodoItem` <-> `todo_items`), as well
@@ -175,7 +225,7 @@
 ## .. _util: fiber_orm/util.html
 ##
 ## ID Field
-## ````````
+## ^^^^^^^^
 ##
 ## Fiber ORM expects every model class to have a field named `id`, with a
 ## corresponding `id` column in the model table. This field must be either a
@@ -266,6 +316,8 @@
 ## anything can be passed as the database object type so long as there is a
 ## defined `withConnection` template that provides a `conn: DbConn` object
 ## to the provided statement body.
+## The generated connection-flavor procedures are intended to work directly
+## with that `conn` value.
 ##
 ## For example, a valid database object implementation that opens a new
 ## connection for every request might look like this:
@@ -285,16 +337,17 @@
 ## .. _pool.DbConnPool: fiber_orm/pool.html#DbConnPool
 ##
 import std/[json, macros, options, sequtils, strutils]
-import db_connector/db_common
-import namespaced_logging, uuids
+import db_connector/[db_common, db_postgres]
+import uuids

 from std/unicode import capitalize

 import ./fiber_orm/db_common as fiber_db_common
-import ./fiber_orm/pool
-import ./fiber_orm/util
+import ./fiber_orm/[pool, util]
+import ./fiber_orm/private/logging

 export pool, util
+export logging.enableDbLogging

 type
  PagedRecords*[T] = object
@@ -302,25 +355,12 @@ type
    records*: seq[T]
    totalRecords*: int

-  DbUpdateError* = object of CatchableError ##\
+  DbUpdateError* = object of CatchableError
    ## Error types raised when a DB modification fails.

-  NotFoundError* = object of CatchableError ##\
+  NotFoundError* = object of CatchableError
    ## Error type raised when no record matches a given ID

-var logService {.threadvar.}: Option[LogService]
-
-proc logQuery*(methodName: string, sqlStmt: string, args: openArray[(string, string)] = []) =
-  # namespaced_logging would do this check for us, but we don't want to even
-  # build the log object if we're not actually logging
-  if logService.isNone: return
-  var log = %*{ "method": methodName, "sql": sqlStmt }
-  for (k, v) in args: log[k] = %v
-  logService.getLogger("fiber_orm/query").debug(log)
-
-proc enableDbLogging*(svc: LogService) =
-  logService = some(svc)
-
 proc newMutateClauses(): MutateClauses =
  return MutateClauses(
    columns: @[],
@@ -346,6 +386,7 @@ proc createRecord*[D: DbConnType, T](db: D, rec: T): T =
    " RETURNING " & columnNamesForModel(rec).join(",")

  logQuery("createRecord", sqlStmt)
+
  let newRow = db.getRow(sql(sqlStmt), mc.values)

  result = rowToModel(T, newRow)
@@ -413,6 +454,36 @@ template getRecord*[D: DbConnType](db: D, modelType: type, id: typed): untyped =

  rowToModel(modelType, row)

+template getRecordForUpdate*(db: db_postgres.DbConn, modelType: type, id: typed): untyped =
+  ## Fetch a record by id and lock it with `FOR UPDATE`.
+  ##
+  ## This is PostgreSQL-specific and should only be used inside a transaction.
+  let sqlStmt =
+    "SELECT " & columnNamesForModel(modelType).join(",") &
+    " FROM " & tableName(modelType) &
+    " WHERE id = ? FOR UPDATE"
+
+  logQuery("getRecordForUpdate", sqlStmt, [("id", $id)])
+  let row = db.getRow(sql(sqlStmt), @[$id])
+
+  if allIt(row, it.len == 0):
+    raise newException(NotFoundError, "no " & modelName(modelType) & " record for id " & $id)
+
+  rowToModel(modelType, row)
+
+template tryGetRecord*[D: DbConnType](db: D, modelType: type, id: typed): untyped =
+  ## Fetch a record by id.
+  let sqlStmt =
+    "SELECT " & columnNamesForModel(modelType).join(",") &
+    " FROM " & tableName(modelType) &
+    " WHERE id = ?"
+
+  logQuery("tryGetRecord", sqlStmt, [("id", $id)])
+  let row = db.getRow(sql(sqlStmt), @[$id])
+
+  if allIt(row, it.len == 0): none[modelType]()
+  else: some(rowToModel(modelType, row))
+
 template findRecordsWhere*[D: DbConnType](
    db: D,
    modelType: type,
@@ -498,25 +569,137 @@ template findRecordsBy*[D: DbConnType](
      else: db.getRow(sql(countStmt), values)[0].parseInt)


+template associate*[D: DbConnType, I, J](
+    db: D,
+    joinTableName: string,
+    rec1: I,
+    rec2: J): void =
+  ## Associate two records via a join table.
+
+  let insertStmt =
+    "INSERT INTO " & joinTableName &
+    " (" & tableName(I) & "_id, " & tableName(J) & "_id) " &
+    " VALUES (?, ?)"
+
+  logQuery("associate", insertStmt, [("id1", $rec1.id), ("id2", $rec2.id)])
+  db.exec(sql(insertStmt), [$rec1.id, $rec2.id])
+
+
+template findViaJoinTable*[D: DbConnType, L](
+    db: D,
+    joinTableName: string,
+    targetType: type,
+    rec: L,
+    page: Option[PaginationParams]): untyped =
+  ## Find all records of `targetType` that are associated with `rec` via a
+  ## join table.
+  let columns = columnNamesForModel(targetType).mapIt("t." & it).join(",")
+
+  var fetchStmt =
+    "SELECT " & columns &
+    " FROM " & tableName(targetType) & " AS t " &
+    " JOIN " & joinTableName & " AS j " &
+    " ON t.id = jt." & tableName(targetType) & "_id " &
+    " WHERE jt." & tableName(rec) & "_id = ?"
+
+  var countStmt =
+    "SELECT COUNT(*) FROM " & joinTableName &
+    " WHERE " & tableName(rec) & "_id = ?"
+
+  if page.isSome: fetchStmt &= getPagingClause(page.get)
+
+  logQuery("findViaJoinTable", fetchStmt, [("id", $rec.id)])
+  let records = db.getAllRows(sql(fetchStmt), $rec.id)
+    .mapIt(rowToModel(targetType, it))
+
+  PagedRecords[targetType](
+    pagination: page,
+    records: records,
+    totalRecords:
+      if page.isNone: records.len
+      else: db.getRow(sql(countStmt))[0].parseInt)
+
+template findViaJoinTable*[D: DbConnType](
+    db: D,
+    joinTableName: string,
+    targetType: type,
+    lookupType: type,
+    id: typed,
+    page: Option[PaginationParams]): untyped =
+  ## Find all records of `targetType` that are associated with a record of
+  ## `lookupType` via a join table.
+  let columns = columnNamesForModel(targetType).mapIt("t." & it).join(",")
+
+  var fetchStmt =
+    "SELECT " & columns &
+    " FROM " & tableName(targetType) & " AS t " &
+    " JOIN " & joinTableName & " AS j " &
+    " ON t.id = jt." & tableName(targetType) & "_id " &
+    " WHERE jt." & tableName(lookupType) & "_id = ?"
+
+  var countStmt =
+    "SELECT COUNT(*) FROM " & joinTableName &
+    " WHERE " & tableName(lookupType) & "_id = ?"
+
+  if page.isSome: fetchStmt &= getPagingClause(page.get)
+
+  logQuery("findViaJoinTable", fetchStmt, [("id", $id)])
+  let records = db.getAllRows(sql(fetchStmt), $id)
+    .mapIt(rowToModel(targetType, it))
+
+  PagedRecords[targetType](
+    pagination: page,
+    records: records,
+    totalRecords:
+      if page.isNone: records.len
+      else: db.getRow(sql(countStmt))[0].parseInt)
+
 macro generateProcsForModels*(dbType: type, modelTypes: openarray[type]): untyped =
  ## Generate all standard access procedures for the given model types. For a
-  ## `model class`_ named `TodoItem`, this will generate the following
-  ## procedures:
+  ## `model class`_ named `TodoItem`, this will generate `dbType` and
+  ## connection overloads for procedures like the following:
  ##
  ## .. code-block:: Nim
  ##    proc getTodoItem*(db: TodoDB, id: idType): TodoItem;
-  ##    proc getAllTodoItems*(db: TodoDB): TodoItem;
+  ##    proc getTodoItem*[D: DbConnType](conn: D, id: idType): TodoItem;
+  ##    proc getTodoItemForUpdate*(conn: db_postgres.DbConn, id: idType): TodoItem;
+  ##    proc tryGetTodoItem*(db: TodoDB, id: idType): Option[TodoItem];
+  ##    proc tryGetTodoItem*[D: DbConnType](conn: D, id: idType): Option[TodoItem];
+  ##    proc getTodoItemIfItExists*(db: TodoDB, id: idType): Option[TodoItem];
+  ##    proc getTodoItemIfItExists*[D: DbConnType](
+  ##      conn: D, id: idType): Option[TodoItem];
+  ##    proc getAllTodoItems*(db: TodoDB): PagedRecords[TodoItem];
+  ##    proc getAllTodoItems*[D: DbConnType](conn: D): PagedRecords[TodoItem];
  ##    proc createTodoItem*(db: TodoDB, rec: TodoItem): TodoItem;
+  ##    proc createTodoItem*[D: DbConnType](conn: D, rec: TodoItem): TodoItem;
  ##    proc deleteTodoItem*(db: TodoDB, rec: TodoItem): bool;
+  ##    proc deleteTodoItem*[D: DbConnType](conn: D, rec: TodoItem): bool;
  ##    proc deleteTodoItem*(db: TodoDB, id: idType): bool;
+  ##    proc deleteTodoItem*[D: DbConnType](conn: D, id: idType): bool;
  ##    proc updateTodoItem*(db: TodoDB, rec: TodoItem): bool;
-  ##    proc createOrUpdateTodoItem*(db: TodoDB, rec: TodoItem): bool;
+  ##    proc updateTodoItem*[D: DbConnType](conn: D, rec: TodoItem): bool;
+  ##    proc createOrUpdateTodoItem*(db: TodoDB, rec: TodoItem): TodoItem;
+  ##    proc createOrUpdateTodoItem*[D: DbConnType](
+  ##      conn: D, rec: TodoItem): TodoItem;
  ##
  ##    proc findTodoItemsWhere*(
-  ##      db: TodoDB, whereClause: string, values: varargs[string]): TodoItem;
+  ##      db: TodoDB,
+  ##      whereClause: string,
+  ##      values: varargs[string, dbFormat],
+  ##      pagination = none[PaginationParams]()): PagedRecords[TodoItem];
+  ##    proc findTodoItemsWhere*[D: DbConnType](
+  ##      conn: D,
+  ##      whereClause: string,
+  ##      values: varargs[string, dbFormat],
+  ##      pagination = none[PaginationParams]()): PagedRecords[TodoItem];
  ##
  ## `dbType` is expected to be some type that has a defined `withConnection`
  ## procedure (see `Database Object`_ for details).
+  ## The `dbType` overloads are convenience wrappers around `withConnection`.
+  ## Inside `inTransaction`, prefer the overloads that take `conn: D` where
+  ## `D: DbConnType` so all operations use the transaction connection.
+  ## The generated `get<RecordName>ForUpdate` helper is PostgreSQL-specific and
+  ## is only available for direct PostgreSQL connections.
  ##
  ## .. _Database Object: #database-object
  result = newStmtList()
@@ -528,6 +711,8 @@ macro generateProcsForModels*(dbType: type, modelTypes: openarray[type]): untype

    let modelName = $(t.getType[1])
    let getName = ident("get" & modelName)
+    let getForUpdateName = ident("get" & modelName & "ForUpdate")
+    let tryGetName = ident("tryGet" & modelName)
    let getIfExistsName = ident("get" & modelName & "IfItExists")
    let getAllName = ident("getAll" & pluralize(modelName))
    let findWhereName = ident("find" & pluralize(modelName) & "Where")
@@ -540,14 +725,35 @@ macro generateProcsForModels*(dbType: type, modelTypes: openarray[type]): untype
      proc `getName`*(db: `dbType`, id: `idType`): `t` =
        db.withConnection conn: result = getRecord(conn, `t`, id)

+      proc `getName`*[D: DbConnType](conn: D, id: `idType`): `t` =
+        result = getRecord(conn, `t`, id)
+
+      proc `getForUpdateName`*(conn: db_postgres.DbConn, id: `idType`): `t` =
+        result = getRecordForUpdate(conn, `t`, id)
+
+      proc `tryGetName`*(db: `dbType`, id: `idType`): Option[`t`] =
+        db.withConnection conn: result = tryGetRecord(conn, `t`, id)
+
+      proc `tryGetName`*[D: DbConnType](conn: D, id: `idType`): Option[`t`] =
+        result = tryGetRecord(conn, `t`, id)
+
      proc `getIfExistsName`*(db: `dbType`, id: `idType`): Option[`t`] =
        db.withConnection conn:
          try: result = some(getRecord(conn, `t`, id))
          except NotFoundError: result = none[`t`]()

+      proc `getIfExistsName`*[D: DbConnType](conn: D, id: `idType`): Option[`t`] =
+        try: result = some(getRecord(conn, `t`, id))
+        except NotFoundError: result = none[`t`]()
+
      proc `getAllName`*(db: `dbType`, pagination = none[PaginationParams]()): PagedRecords[`t`] =
        db.withConnection conn: result = getAllRecords(conn, `t`, pagination)

+      proc `getAllName`*[D: DbConnType](
+          conn: D,
+          pagination = none[PaginationParams]()): PagedRecords[`t`] =
+        result = getAllRecords(conn, `t`, pagination)
+
      proc `findWhereName`*(
          db: `dbType`,
          whereClause: string,
@@ -556,21 +762,43 @@ macro generateProcsForModels*(dbType: type, modelTypes: openarray[type]): untype
        db.withConnection conn:
          result = findRecordsWhere(conn, `t`, whereClause, values, pagination)

+      proc `findWhereName`*[D: DbConnType](
+          conn: D,
+          whereClause: string,
+          values: varargs[string, dbFormat],
+          pagination = none[PaginationParams]()): PagedRecords[`t`] =
+        result = findRecordsWhere(conn, `t`, whereClause, values, pagination)
+
      proc `createName`*(db: `dbType`, rec: `t`): `t` =
        db.withConnection conn: result = createRecord(conn, rec)

+      proc `createName`*[D: DbConnType](conn: D, rec: `t`): `t` =
+        result = createRecord(conn, rec)
+
      proc `updateName`*(db: `dbType`, rec: `t`): bool =
        db.withConnection conn: result = updateRecord(conn, rec)

+      proc `updateName`*[D: DbConnType](conn: D, rec: `t`): bool =
+        result = updateRecord(conn, rec)
+
      proc `createOrUpdateName`*(db: `dbType`, rec: `t`): `t` =
        db.inTransaction: result = createOrUpdateRecord(conn, rec)

+      proc `createOrUpdateName`*[D: DbConnType](conn: D, rec: `t`): `t` =
+        result = createOrUpdateRecord(conn, rec)
+
      proc `deleteName`*(db: `dbType`, rec: `t`): bool =
        db.withConnection conn: result = deleteRecord(conn, rec)

+      proc `deleteName`*[D: DbConnType](conn: D, rec: `t`): bool =
+        result = deleteRecord(conn, rec)
+
      proc `deleteName`*(db: `dbType`, id: `idType`): bool =
        db.withConnection conn: result = deleteRecord(conn, `t`, id)

+      proc `deleteName`*[D: DbConnType](conn: D, id: `idType`): bool =
+        result = deleteRecord(conn, `t`, id)
+
 macro generateLookup*(dbType: type, modelType: type, fields: seq[string]): untyped =
  ## Create a lookup procedure for a given set of field names. For example,
  ## given the TODO database demostrated above,
@@ -582,42 +810,49 @@ macro generateLookup*(dbType: type, modelType: type, fields: seq[string]): untyp
  ##
  ## .. code-block:: Nim
  ##    proc findTodoItemsByOwnerAndPriority*(db: SampleDB,
-  ##      owner: string, priority: int): seq[TodoItem]
+  ##      owner: string, priority: int,
+  ##      pagination = none[PaginationParams]()): PagedRecords[TodoItem]
+  ##    proc findTodoItemsByOwnerAndPriority*[D: DbConnType](conn: D,
+  ##      owner: string, priority: int,
+  ##      pagination = none[PaginationParams]()): PagedRecords[TodoItem]
+  ##
+  ## Use the `db` overload for standalone calls and the `conn` overload inside
+  ## `withConnection` or `inTransaction`.
  let fieldNames = fields[1].mapIt($it)
  let procName = ident("find" & pluralize($modelType.getType[1]) & "By" & fieldNames.mapIt(it.capitalize).join("And"))
-
-  # Create proc skeleton
-  result = quote do:
-    proc `procName`*(db: `dbType`): PagedRecords[`modelType`] =
-      db.withConnection conn: result = findRecordsBy(conn, `modelType`)
-
  var callParams = quote do: @[]

-  # Add dynamic parameters for the proc definition and inner proc call
+  # Add dynamic parameters for the generated proc and inner proc call.
  for n in fieldNames:
    let paramTuple = newNimNode(nnkPar)
    paramTuple.add(newColonExpr(ident("field"), newLit(identNameToDb(n))))
    paramTuple.add(newColonExpr(ident("value"), ident(n)))
-
-    # Add the parameter to the outer call (the generated proc)
-    # result[3] is ProcDef -> [3]: FormalParams
-    result[3].add(newIdentDefs(ident(n), ident("string")))
-
-    # Build up the AST for the inner procedure call
    callParams[1].add(paramTuple)

-  # Add the optional pagination parameters to the generated proc definition
-  result[3].add(newIdentDefs(
+  let dbProcDefAST = quote do:
+    proc `procName`*(db: `dbType`): PagedRecords[`modelType`] =
+      db.withConnection conn:
+        result = findRecordsBy(conn, `modelType`, `callParams`, pagination)
+
+  let connProcDefAST = quote do:
+    proc `procName`*[D: DbConnType](conn: D): PagedRecords[`modelType`] =
+      result = findRecordsBy(conn, `modelType`, `callParams.copyNimTree`, pagination)
+
+  for n in fieldNames:
+    dbProcDefAST[3].add(newIdentDefs(ident(n), ident("string")))
+    connProcDefAST[3].add(newIdentDefs(ident(n), ident("string")))
+
+  dbProcDefAST[3].add(newIdentDefs(
    ident("pagination"), newEmptyNode(),
    quote do: none[PaginationParams]()))

-  # Add the call params to the inner procedure call
-  # result[6][0][1][0][1] is
-  #   ProcDef -> [6]: StmtList (body) -> [0]: Command ->
-  #     [2]: StmtList (withConnection body) -> [0]: Asgn (result =) ->
-  #     [1]: Call (inner findRecords invocation)
-  result[6][0][2][0][1].add(callParams)
-  result[6][0][2][0][1].add(quote do: pagination)
+  connProcDefAST[3].add(newIdentDefs(
+    ident("pagination"), newEmptyNode(),
+    quote do: none[PaginationParams]()))
+
+  result = newStmtList()
+  result.add dbProcDefAST
+  result.add connProcDefAST

 macro generateProcsForFieldLookups*(dbType: type, modelsAndFields: openarray[tuple[t: type, fields: seq[string]]]): untyped =
  result = newStmtList()
@@ -627,63 +862,212 @@ macro generateProcsForFieldLookups*(dbType: type, modelsAndFields: openarray[tup
    let fieldNames = i[1][1][1].mapIt($it)

    let procName = ident("find" & $modelType & "sBy" & fieldNames.mapIt(it.capitalize).join("And"))
-
-    # Create proc skeleton
-    let procDefAST = quote do:
-      proc `procName`*(db: `dbType`): PagedRecords[`modelType`] =
-        db.withConnection conn: result = findRecordsBy(conn, `modelType`)
-
    var callParams = quote do: @[]

-    # Add dynamic parameters for the proc definition and inner proc call
+    # Add dynamic parameters for the generated proc and inner proc call.
    for n in fieldNames:
      let paramTuple = newNimNode(nnkPar)
      paramTuple.add(newColonExpr(ident("field"), newLit(identNameToDb(n))))
      paramTuple.add(newColonExpr(ident("value"), ident(n)))
-
-      procDefAST[3].add(newIdentDefs(ident(n), ident("string")))
      callParams[1].add(paramTuple)

-    # Add the optional pagination parameters to the generated proc definition
-    procDefAST[3].add(newIdentDefs(
+    let dbProcDefAST = quote do:
+      proc `procName`*(db: `dbType`): PagedRecords[`modelType`] =
+        db.withConnection conn:
+          result = findRecordsBy(conn, `modelType`, `callParams`, pagination)
+
+    let connProcDefAST = quote do:
+      proc `procName`*[D: DbConnType](conn: D): PagedRecords[`modelType`] =
+        result = findRecordsBy(conn, `modelType`, `callParams.copyNimTree`, pagination)
+
+    for n in fieldNames:
+      dbProcDefAST[3].add(newIdentDefs(ident(n), ident("string")))
+      connProcDefAST[3].add(newIdentDefs(ident(n), ident("string")))
+
+    dbProcDefAST[3].add(newIdentDefs(
      ident("pagination"), newEmptyNode(),
      quote do: none[PaginationParams]()))

-    procDefAST[6][0][1][0][1].add(callParams)
-    procDefAST[6][0][1][0][1].add(quote do: pagination)
+    connProcDefAST[3].add(newIdentDefs(
+      ident("pagination"), newEmptyNode(),
+      quote do: none[PaginationParams]()))

-    result.add procDefAST
+    result.add dbProcDefAST
+    result.add connProcDefAST

-proc initPool*[D: DbConnType](
-    connect: proc(): D,
-    poolSize = 10,
-    hardCap = false,
-    healthCheckQuery = "SELECT 'true' AS alive"): DbConnPool[D] =
-
-  ## Initialize a new DbConnPool. See the `initDb` procedure in the `Example
-  ## Fiber ORM Usage`_ for an example
+macro generateJoinTableProcs*(
+    dbType, model1Type, model2Type: type,
+    joinTableName: string): untyped =
+  ## Generate lookup procedures for a pair of models with a join table. For
+  ## example, given the TODO database demonstrated above, where `TodoItem` and
+  ## `TimeEntry` have a many-to-many relationship, you might have a join table
+  ## `todo_items_time_entries` with columns `todo_item_id` and `time_entry_id`.
+  ## This macro will generate the following procedures:
  ##
-  ## * `connect` must be a factory which creates a new `DbConn`.
-  ## * `poolSize` sets the desired capacity of the connection pool.
-  ## * `hardCap` defaults to `false`.
-  ##   When `false`, the pool can grow beyond the configured capacity, but will
-  ##   release connections down to the its capacity (no less than `poolSize`).
+  ## .. code-block:: Nim
+  ##    proc getTodoItemsByTimeEntry*(db: SampleDB, timeEntry: TimeEntry,
+  ##      pagination = none[PaginationParams]()): PagedRecords[TodoItem]
+  ##    proc getTodoItemsByTimeEntry*[D: DbConnType](conn: D, timeEntry: TimeEntry,
+  ##      pagination = none[PaginationParams]()): PagedRecords[TodoItem]
+  ##    proc getTimeEntriesByTodoItem*(db: SampleDB, todoItem: TodoItem,
+  ##      pagination = none[PaginationParams]()): PagedRecords[TimeEntry]
+  ##    proc getTimeEntriesByTodoItem*[D: DbConnType](conn: D, todoItem: TodoItem,
+  ##      pagination = none[PaginationParams]()): PagedRecords[TimeEntry]
  ##
-  ##   When `true` the pool will not create more than its configured capacity.
-  ##   It a connection is requested, none are free, and the pool is at
-  ##   capacity, this will result in an Error being raised.
-  ## * `healthCheckQuery` should be a simple and fast SQL query that the pool
-  ##   can use to test the liveliness of pooled connections.
+  ## `dbType` is expected to be some type that has a defined `withConnection`
+  ## procedure (see `Database Object`_ for details).
+  ## As with the other generated helpers, use the connection overloads when
+  ## you are already inside `withConnection` or `inTransaction`.
  ##
-  ## .. _Example Fiber ORM Usage: #basic-usage-example-fiber-orm-usage
+  ## .. _Database Object: #database-object
+  result = newStmtList()

-  initDbConnPool(DbConnPoolConfig[D](
-    connect: connect,
-    poolSize: poolSize,
-    hardCap: hardCap,
-    healthCheckQuery: healthCheckQuery))
+  if model1Type.getType[1].typeKind == ntyRef or
+     model2Type.getType[1].typeKind == ntyRef:
+    raise newException(ValueError,
+      "fiber_orm model object must be objects, not refs")
+
+  let model1Name = $(model1Type.getType[1])
+  let model2Name = $(model2Type.getType[1])
+  let getModel1Name = ident("get" & pluralize(model1Name) & "By" & model2Name)
+  let getModel2Name = ident("get" & pluralize(model2Name) & "By" & model1Name)
+  let id1Type = typeOfColumn(model1Type, "id")
+  let id2Type = typeOfColumn(model2Type, "id")
+  let joinTableNameNode = newStrLitNode($joinTableName)
+
+  result.add quote do:
+    proc `getModel1Name`*(
+        db: `dbType`,
+        id: `id2Type`,
+        pagination = none[PaginationParams]()): PagedRecords[`model1Type`] =
+      db.withConnection conn:
+        result = findViaJoinTable(
+          conn,
+          `joinTableNameNode`,
+          `model1Type`,
+          `model2Type`,
+          id,
+          pagination)
+
+    proc `getModel1Name`*[D: DbConnType](
+        conn: D,
+        id: `id2Type`,
+        pagination = none[PaginationParams]()): PagedRecords[`model1Type`] =
+      result = findViaJoinTable(
+        conn,
+        `joinTableNameNode`,
+        `model1Type`,
+        `model2Type`,
+        id,
+        pagination)
+
+    proc `getModel1Name`*(
+        db: `dbType`,
+        rec: `model2Type`,
+        pagination = none[PaginationParams]()): PagedRecords[`model1Type`] =
+      db.withConnection conn:
+        result = findViaJoinTable(
+          conn,
+          `joinTableNameNode`,
+          `model1Type`,
+          rec,
+          pagination)
+
+    proc `getModel1Name`*[D: DbConnType](
+        conn: D,
+        rec: `model2Type`,
+        pagination = none[PaginationParams]()): PagedRecords[`model1Type`] =
+      result = findViaJoinTable(
+        conn,
+        `joinTableNameNode`,
+        `model1Type`,
+        rec,
+        pagination)
+
+    proc `getModel2Name`*(
+        db: `dbType`,
+        id: `id1Type`,
+        pagination = none[PaginationParams]()): PagedRecords[`model2Type`] =
+      db.withConnection conn:
+        result = findViaJoinTable(
+          conn,
+          `joinTableNameNode`,
+          `model2Type`,
+          `model1Type`,
+          id,
+          pagination)
+
+    proc `getModel2Name`*[D: DbConnType](
+        conn: D,
+        id: `id1Type`,
+        pagination = none[PaginationParams]()): PagedRecords[`model2Type`] =
+      result = findViaJoinTable(
+        conn,
+        `joinTableNameNode`,
+        `model2Type`,
+        `model1Type`,
+        id,
+        pagination)
+
+    proc `getModel2Name`*(
+        db: `dbType`,
+        rec: `model1Type`,
+        pagination = none[PaginationParams]()): PagedRecords[`model2Type`] =
+      db.withConnection conn:
+        result = findViaJoinTable(
+          conn,
+          `joinTableNameNode`,
+          `model2Type`,
+          rec,
+          pagination)
+
+    proc `getModel2Name`*[D: DbConnType](
+        conn: D,
+        rec: `model1Type`,
+        pagination = none[PaginationParams]()): PagedRecords[`model2Type`] =
+      result = findViaJoinTable(
+        conn,
+        `joinTableNameNode`,
+        `model2Type`,
+        rec,
+        pagination)
+
+    proc associate*(
+        db: `dbType`,
+        rec1: `model1Type`,
+        rec2: `model2Type`): void =
+      db.withConnection conn:
+        associate(conn, `joinTableNameNode`, rec1, rec2)
+
+    proc associate*[D: DbConnType](
+        conn: D,
+        rec1: `model1Type`,
+        rec2: `model2Type`): void =
+      associate(conn, `joinTableNameNode`, rec1, rec2)
+
+    proc associate*(
+        db: `dbType`,
+        rec2: `model2Type`,
+        rec1: `model1Type`): void =
+      db.withConnection conn:
+        associate(conn, `joinTableNameNode`, rec1, rec2)
+
+    proc associate*[D: DbConnType](
+        conn: D,
+        rec2: `model2Type`,
+        rec1: `model1Type`): void =
+      associate(conn, `joinTableNameNode`, rec1, rec2)

 template inTransaction*(db, body: untyped) =
+  ## Execute `body` inside a transaction using a single connection bound to
+  ## `conn`.
+  ##
+  ## When calling generated Fiber ORM helpers inside this block, use the
+  ## overloads that take `conn: D` where `D: DbConnType`. Do not call the
+  ## overloads that take the outer database object, because those call
+  ## `withConnection` again and may acquire a different connection.
+  ## If you need to lock a PostgreSQL row before modifying it, use the
+  ## generated `get<RecordName>ForUpdate` helper.
  db.withConnection conn:
    conn.exec(sql"BEGIN TRANSACTION")
    try:
--- a/src/fiber_orm/pool.nim
+++ b/src/fiber_orm/pool.nim
@@ -4,85 +4,77 @@

 ## Simple database connection pooling implementation compatible with Fiber ORM.

-import std/[sequtils, strutils, sugar]
+when (NimMajor, NimMinor, NimPatch) < (2, 0, 0):
+  when not defined(gcArc) and not defined (gcOrc):
+    {.error: "fiber_orm requires either --mm:arc or --mm:orc.".}
+
+import std/[deques, locks, sequtils, sugar]
 import db_connector/db_common

 from db_connector/db_sqlite import getRow, close
 from db_connector/db_postgres import getRow, close

 import ./db_common as fiber_db_common
+import ./private/logging

 type
-  DbConnPoolConfig*[D: DbConnType] = object
-    connect*: () -> D   ## Factory procedure to create a new DBConn
-    poolSize*: int      ## The pool capacity.
+  DbConnPool*[D: DbConnType] = ptr DbConnPoolObj[D]

-    hardCap*: bool      ## Is the pool capacity a hard cap?
-                        ##
-                        ## When `false`, the pool can grow beyond the
-                        ## configured capacity, but will release connections
-                        ## down to the its capacity (no less than `poolSize`).
-                        ##
-                        ## When `true` the pool will not create more than its
-                        ## configured capacity.  It a connection is requested,
-                        ## none are free, and the pool is at capacity, this
-                        ## will result in an Error being raised.
-
-    healthCheckQuery*: string ## Should be a simple and fast SQL query that the
-                              ## pool can use to test the liveliness of pooled
-                              ## connections.
-
-  PooledDbConn[D: DbConnType] = ref object
-    conn: D
-    id: int
-    free: bool
-
-  DbConnPool*[D: DbConnType] = ref object
+  DbConnPoolObj[D: DbConnType] = object
    ## Database connection pool
-    conns: seq[PooledDbConn[D]]
-    cfg: DbConnPoolConfig[D]
-    lastId: int
+    connect: proc (): D {.raises: [DbError].}
+    healthCheckQuery: SqlQuery
+    entries: Deque[D]
+    cond: Cond
+    lock: Lock

-proc initDbConnPool*[D: DbConnType](cfg: DbConnPoolConfig[D]): DbConnPool[D] =
-  result = DbConnPool[D](
-    conns: @[],
-    cfg: cfg)

-proc newConn[D: DbConnType](pool: DbConnPool[D]): PooledDbConn[D] =
-  pool.lastId += 1
-  {.gcsafe.}:
-    let conn = pool.cfg.connect()
-    result = PooledDbConn[D](
-      conn: conn,
-      id: pool.lastId,
-      free: true)
-    pool.conns.add(result)
+proc close*[D: DbConnType](pool: DbConnPool[D]) =
+  ## Safely close all connections and release resources for the given pool.
+  getLogger("pool").debug("closing connection pool")
+  withLock(pool.lock):
+    while pool.entries.len > 0: close(pool.entries.popFirst())

-proc maintain[D: DbConnType](pool: DbConnPool[D]): void =
-  pool.conns.keepIf(proc (pc: PooledDbConn[D]): bool =
-    if not pc.free: return true
+  deinitLock(pool.lock)
+  deinitCond(pool.cond)
+  `=destroy`(pool[])
+  deallocShared(pool)

-    try:
-      discard getRow(pc.conn, sql(pool.cfg.healthCheckQuery), [])
-      return true
-    except:
-      try: pc.conn.close()  # try to close the connection
-      except: discard ""
-      return false
-  )

-  let freeConns = pool.conns.filterIt(it.free)
-  if pool.conns.len > pool.cfg.poolSize and freeConns.len > 0:
-    let numToCull = min(freeConns.len, pool.conns.len - pool.cfg.poolSize)
+proc newDbConnPool*[D: DbConnType](
+    poolSize: int,
+    connectFunc: proc(): D {.raises: [DbError].},
+    healthCheckQuery = "SELECT 1;"): DbConnPool[D] =
+  ## Initialize a new DbConnPool. See the `initDb` procedure in the `Example
+  ## Fiber ORM Usage`_ for an example
+  ##
+  ## * `connect` must be a factory which creates a new `DbConn`.
+  ## * `poolSize` sets the desired capacity of the connection pool.
+  ## * `healthCheckQuery` should be a simple and fast SQL query that the pool
+  ##   can use to test the liveliness of pooled connections. By default it uses
+  ##   `SELECT 1;`
+  ##
+  ## .. _Example Fiber ORM Usage: ../fiber_orm.html#basic-usage-example-fiber-orm-usage

-    if numToCull > 0:
-      let toCull = freeConns[0..numToCull]
-      pool.conns.keepIf((pc) => toCull.allIt(it.id != pc.id))
-      for culled in toCull:
-        try: culled.conn.close()
-        except: discard ""
+  result = cast[DbConnPool[D]](allocShared0(sizeof(DbConnPoolObj[D])))
+  initCond(result.cond)
+  initLock(result.lock)
+  result.entries = initDeque[D](poolSize)
+  result.connect = connectFunc
+  result.healthCheckQuery = sql(healthCheckQuery)

-proc take*[D: DbConnType](pool: DbConnPool[D]): tuple[id: int, conn: D] =
+  try:
+    for _ in 0 ..< poolSize: result.entries.addLast(connectFunc())
+  except DbError as ex:
+    try: result.close()
+    except: discard
+    getLogger("pool").error(
+      msg = "unable to initialize connection pool",
+      err = ex)
+    raise ex
+
+
+proc take*[D: DbConnType](pool: DbConnPool[D]): D {.raises: [DbError], gcsafe.} =
  ## Request a connection from the pool. Returns a DbConn if the pool has free
  ## connections, or if it has the capacity to create a new connection. If the
  ## pool is configured with a hard capacity limit and is out of free
@@ -90,25 +82,33 @@ proc take*[D: DbConnType](pool: DbConnPool[D]): tuple[id: int, conn: D] =
  ##
  ## Connections taken must be returned via `release` when the caller is
  ## finished using them in order for them to be released back to the pool.
-  pool.maintain
-  let freeConns = pool.conns.filterIt(it.free)
+  withLock(pool.lock):
+    while pool.entries.len == 0: wait(pool.cond, pool.lock)
+    result = pool.entries.popFirst()

-  let reserved =
-    if freeConns.len > 0: freeConns[0]
-    else: pool.newConn()
+    # check that the connection is healthy
+    try: discard getRow(result, pool.healthCheckQuery, [])
+    except DbError:
+      {.gcsafe.}:
+        # if it's not, let's try to close it and create a new connection
+        try:
+          getLogger("pool").info(
+            "pooled connection failed health check, opening a new connection")
+          close(result)
+        except: discard
+        result = pool.connect()

-  reserved.free = false
-  return (id: reserved.id, conn: reserved.conn)

-proc release*[D: DbConnType](pool: DbConnPool[D], connId: int): void =
+proc release*[D: DbConnType](pool: DbConnPool[D], conn: D) {.raises: [], gcsafe.} =
  ## Release a connection back to the pool.
-  let foundConn = pool.conns.filterIt(it.id == connId)
-  if foundConn.len > 0: foundConn[0].free = true
+  withLock(pool.lock):
+    pool.entries.addLast(conn)
+  signal(pool.cond)

 template withConnection*[D: DbConnType](pool: DbConnPool[D], conn, stmt: untyped): untyped =
  ## Convenience template to provide a connection from the pool for use in a
  ## statement block, automatically releasing that connnection when done.
  block:
-    let (connId, conn) = take(pool)
+    let conn = take(pool)
    try: stmt
-    finally: release(pool, connId)
+    finally: release(pool, conn)
--- a/src/fiber_orm/private/logging.nim
+++ b/src/fiber_orm/private/logging.nim
@@ -0,0 +1,34 @@
+import std/[json, options]
+
+import namespaced_logging
+
+export namespaced_logging.log
+export namespaced_logging.debug
+export namespaced_logging.info
+export namespaced_logging.notice
+export namespaced_logging.warn
+export namespaced_logging.error
+export namespaced_logging.fatal
+
+var logService {.threadvar.}: Option[ThreadLocalLogService]
+var logger {.threadvar.}: Option[Logger]
+
+proc makeQueryLogEntry(
+    m: string,
+    sql: string,
+    args: openArray[(string, string)] = []): JsonNode =
+  result = %*{ "method": m, "sql": sql }
+  for (k, v) in args: result[k] = %v
+
+proc logQuery*(methodName: string, sqlStmt: string, args: openArray[(string, string)] = []) =
+  # namespaced_logging would do this check for us, but we don't want to even
+  # build the log object if we're not actually logging
+  if logService.isNone: return
+  if logger.isNone: logger = logService.getLogger("fiber_orm/query")
+  logger.debug(makeQueryLogEntry(methodName, sqlStmt, args))
+
+proc enableDbLogging*(svc: ThreadLocalLogService) =
+  logService = some(svc)
+
+proc getLogger*(scope: string): Option[Logger] =
+  logService.getLogger("fiber_orm/" & scope)
--- a/src/fiber_orm/util.nim
+++ b/src/fiber_orm/util.nim
@@ -217,7 +217,7 @@ proc parseDbArray*(val: string): seq[string] =
    result.add(curStr)

 func createParseStmt*(t, value: NimNode): NimNode =
-  ## Utility method to create the Nim cod required to parse a value coming from
+  ## Utility method to create the Nim code required to parse a value coming from
  ## the a database query. This is used by functions like `rowToModel` to parse
  ## the dataabase columns into the Nim object fields.

@@ -240,7 +240,7 @@ func createParseStmt*(t, value: NimNode): NimNode =
    elif t.getType == DateTime.getType:
      result = quote do: parsePGDatetime(`value`)

-    else: error "Unknown value object type: " & $t.getTypeInst
+    else: error "Cannot parse column with unknown object type: " & $t.getTypeInst

  elif t.typeKind == ntyGenericInst:

@@ -254,7 +254,13 @@ func createParseStmt*(t, value: NimNode): NimNode =
        if `value`.len == 0:  none[`innerType`]()
        else:                 some(`parseStmt`)

-    else: error "Unknown generic instance type: " & $t.getTypeInst
+    else: error "Cannot parse column with unknown generic instance type: " & $t.getTypeInst
+
+  elif t.typeKind == ntyDistinct:
+    result = quote do:
+      block:
+        let tmp: `t` = `value`
+        tmp

  elif t.typeKind == ntyRef:

@@ -262,7 +268,7 @@ func createParseStmt*(t, value: NimNode): NimNode =
      result = quote do: parseJson(`value`)

    else:
-      error "Unknown ref type: " & $t.getTypeInst
+      error "Cannot parse column with unknown ref type: " & $t.getTypeInst

  elif t.typeKind == ntySequence:
    let innerType = t[1]
@@ -281,14 +287,14 @@ func createParseStmt*(t, value: NimNode): NimNode =
    result = quote do: parseFloat(`value`)

  elif t.typeKind == ntyBool:
-    result = quote do: "true".startsWith(`value`.toLower)
+    result = quote do: "true".startsWith(`value`.toLower) or `value` == "1"

  elif t.typeKind == ntyEnum:
    let innerType = t.getTypeInst
    result = quote do: parseEnum[`innerType`](`value`)

  else:
-    error "Unknown value type: " & $t.typeKind
+    error "Cannot parse column with unknown value type: " & $t.typeKind

 func fields(t: NimNode): seq[tuple[fieldIdent: NimNode, fieldType: NimNode]] =
  #[
Author	SHA1	Message	Date
Jonathan Bernard	2301da8143	Add PostgreSQL FOR UPDATE getters Add a PostgreSQL-specific getRecordForUpdate helper that appends FOR UPDATE to the generated SELECT statement so callers can lock a row inside an explicit transaction. generateProcsForModels now always emits a direct-connection get<RecordName>ForUpdate proc that accepts db_postgres.DbConn. There is intentionally no dbType overload for this API, because reacquiring a connection via withConnection would defeat the lock's transactional scope. The source docs and README now document the new helper and show the intended usage pattern inside inTransaction: db.inTransaction: var item = conn.getTodoItemForUpdate(todoId) item.priority += 1 discard conn.updateTodoItem(item)	2026-03-24 22:04:49 -05:00
Jonathan Bernard	71cb5a7cff	Update documentation for new signature changes, bump version.	2026-03-24 21:48:51 -05:00
Jonathan Bernard	1a9314fe4f	Add connection overloads for generated ORM procs The generated ORM helpers currently only accept the database wrapper type as their first argument. That works well for the common case, but it becomes misleading inside inTransaction blocks because the generated proc will call withConnection again and may therefore use a different connection than the one that is participating in the transaction. Add DbConnType-constrained overloads for the generated model CRUD/query procs, generated lookups, and generated join-table helpers. This lets callers explicitly use the transaction connection while keeping the existing dbType-based API intact for non-transactional call sites. This makes the intended transactional usage straightforward: db.inTransaction: var userRecord = conn.getUser("userId1") userRecord.visitCount += 1 discard conn.updateUser(userRecord) AI-Assisted: yes AI-Tool: OpenAI Codes / gpt-5.4 xhigh	2026-03-24 21:39:25 -05:00
Jonathan Bernard	bb36bba864	Support distinct versions of types we know how to convert.	2025-09-02 00:40:00 -05:00
Jonathan Bernard	f54bf6e974	Add tryGet<RecordName> versions of get<Record> calls `tryGet<RecordName>` returns Option types rather than raise exceptions. For example: generateProcsForModels(MyDb, [ User ]) will now create both: proc getUser(db: MyDb, id: string): User proc tryGetUser(db: MyDb, id: string): Option[User]	2025-09-02 00:36:11 -05:00
Jonathan Bernard	e1fa2480d0	Major update to provide thread-safe, robust connection pooling. Taking inspiration from the waterpark library, the connection pooling mechanism has been refactored to be thread-safe. Additionally, the pooling logic detects and handles stale connections in the pool. When a connection is requested from the pool, the pool first validates that it is healthy and replaces it with a fresh connection if necessary. This is transparent to the requester. Additionally we refactored the internal logging implementation to make it more conventient to access logging infrastructure and log from various sub-scopes within fiber_orm (query, pool, etc.)	2025-07-27 17:47:07 -05:00
Jonathan Bernard	b8c64cc693	Migrate to namespaced_logging v2.	2025-07-12 07:54:13 -05:00
Jonathan Bernard	aa02f9f5b1	Add support for records associated via join tables.	2025-05-19 17:56:40 -05:00
Jonathan Bernard	9d1cc4bbec	Cache logger instance.	2025-01-20 06:39:02 -06:00