Support distinct versions of types we know how to convert.

`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]

fiber_orm.nimble

@@ -1,6 +1,6 @@
 # Package
 
-version       = "4.0.0"
+version       = "4.1.0"
 author        = "Jonathan Bernard"
 description   = "Lightweight Postgres ORM for Nim."
 license       = "GPL-3.0"

src/fiber_orm.nim

@@ -334,7 +334,6 @@ proc createRecord*[D: DbConnType, T](db: D, rec: T): T =
     " RETURNING " & columnNamesForModel(rec).join(",")
 
   logQuery("createRecord", sqlStmt)
-  debug(getLogger("query"), %*{ "values": mc.values })
 
   let newRow = db.getRow(sql(sqlStmt), mc.values)
 
@@ -403,6 +402,19 @@ template getRecord*[D: DbConnType](db: D, modelType: type, id: typed): untyped =
 
   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,
@@ -603,6 +615,7 @@ macro generateProcsForModels*(dbType: type, modelTypes: openarray[type]): untype
 
     let modelName = $(t.getType[1])
     let getName = ident("get" & modelName)
+    let tryGetName = ident("tryGet" & modelName)
     let getIfExistsName = ident("get" & modelName & "IfItExists")
     let getAllName = ident("getAll" & pluralize(modelName))
     let findWhereName = ident("find" & pluralize(modelName) & "Where")
@@ -615,6 +628,9 @@ macro generateProcsForModels*(dbType: type, modelTypes: openarray[type]): untype
       proc `getName`*(db: `dbType`, id: `idType`): `t` =
         db.withConnection conn: result = getRecord(conn, `t`, id)
 
+      proc `tryGetName`*(db: `dbType`, id: `idType`): Option[`t`] =
+        db.withConnection conn: result = tryGetRecord(conn, `t`, id)
+
       proc `getIfExistsName`*(db: `dbType`, id: `idType`): Option[`t`] =
         db.withConnection conn:
           try: result = some(getRecord(conn, `t`, id))

src/fiber_orm/util.nim

@@ -256,6 +256,12 @@ func createParseStmt*(t, value: NimNode): NimNode =
 
     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:
 
     if $t.getTypeInst == "JsonNode":