Add createOrUpdateRecord and record method generators.

`createOrUpdateRecord` implements upsert: update an existing record if
it exists or create a new record if not. A new error `DbUpdateError` was
added to be raised when an existing record does exist but was not able
to be updated.

src/fiber_orm.nim

@@ -107,6 +107,7 @@
 ##
 ##    proc createTodoItem*(db: TodoDB, rec: TodoItem): TodoItem;
 ##    proc updateTodoItem*(db: TodoDB, rec: TodoItem): bool;
+##    proc createOrUpdateTodoItem*(db: TodoDB, rec: TodoItem): bool;
 ##    proc deleteTodoItem*(db: TodoDB, rec: TodoItem): bool;
 ##    proc deleteTodoItem*(db: TodoDB, id: UUID): bool;
 ##
@@ -312,6 +313,9 @@ type
     records*: seq[T]
     totalRecords*: int
 
+  DbUpdateError* = object of CatchableError ##\
+    ## Error types raised when a DB modification fails.
+
   NotFoundError* = object of CatchableError ##\
     ## Error type raised when no record matches a given ID
 
@@ -366,6 +370,24 @@ proc updateRecord*[D: DbConnType, T](db: D, rec: T): bool =
 
   return numRowsUpdated > 0;
 
+proc createOrUpdateRecord*[D: DbConnType, T](db: D, rec: T): T =
+  ## Create or update a record. `rec` is expected to be a `model class`_. If
+  ## the `id` field is unset, or if there is no existing record with the given
+  ## id, a new record is inserted. Otherwise, the existing record is updated.
+  ##
+  ## Note that this does not perform partial updates, all fields are updated.
+
+  let findRecordStmt = "SELECT id FROM " & tableName(rec) & " WHERE id = ?"
+  log().debug "createOrUpdateRecord: [" & findRecordStmt & "] id: " & $rec.id
+  let rows = db.getAllRows(sql(findRecordStmt), [$rec.id])
+
+  if rows.len == 0: result = createRecord(db, rec)
+  else:
+    result = rec
+    if not updateRecord(db, rec):
+      raise newException(DbUpdateError,
+        "unable to update " & modelName(rec) & " for id " & $rec.id)
+
 template deleteRecord*[D: DbConnType](db: D, modelType: type, id: typed): untyped =
   ## Delete a record by id.
   let sqlStmt = "DELETE FROM " & tableName(modelType) & " WHERE id = ?"
@@ -516,6 +538,7 @@ macro generateProcsForModels*(dbType: type, modelTypes: openarray[type]): untype
   ##    proc deleteTodoItem*(db: TodoDB, rec: TodoItem): bool;
   ##    proc deleteTodoItem*(db: TodoDB, id: idType): bool;
   ##    proc updateTodoItem*(db: TodoDB, rec: TodoItem): bool;
+  ##    proc createOrUpdateTodoItem*(db: TodoDB, rec: TodoItem): bool;
   ##
   ##    proc findTodoItemsWhere*(
   ##      db: TodoDB, whereClause: string, values: varargs[string]): TodoItem;
@@ -537,6 +560,7 @@ macro generateProcsForModels*(dbType: type, modelTypes: openarray[type]): untype
     let findWhereName = ident("find" & pluralize(modelName) & "Where")
     let createName = ident("create" & modelName)
     let updateName = ident("update" & modelName)
+    let createOrUpdateName = ident("createOrUpdate" & modelName)
     let deleteName = ident("delete" & modelName)
     let idType = typeOfColumn(t, "id")
     result.add quote do:
@@ -560,6 +584,9 @@ macro generateProcsForModels*(dbType: type, modelTypes: openarray[type]): untype
       proc `updateName`*(db: `dbType`, rec: `t`): bool =
         db.withConn: result = updateRecord(conn, rec)
 
+      proc `createOrUpdateName`*(db: `dbType`, rec: `t`): `t` =
+        db.inTransaction: result = createOrUpdateRecord(conn, rec)
+
       proc `deleteName`*(db: `dbType`, rec: `t`): bool =
         db.withConn: result = deleteRecord(conn, rec)
 

src/fiber_orm/util.nim

@@ -102,7 +102,7 @@ proc dbFormat*[T](list: seq[T]): string =
 
 proc dbFormat*[T](item: T): string =
   ## For all other types, fall back on a defined `$` function to create a
-  ## string version of the value we can include in an SQL query>
+  ## string version of the value we can include in an SQL query.
   return $item
 
 type DbArrayParseState = enum