**feat(sqlite): enhance JSON handling and update type mapping**

- **JSON Type Mapping**:
  - Replace `datatypes.JSON` with `datatypes.JSONMap` for more versatile JSON and JSONB handling in SQLite mappings.
- **E2E Tests**:
  - Add `json_col` to the test schema for JSONB field support.
  - Update test records with new JSON field initialization, inserts, and updates.
- **Custom Type Mapping**:
  - Implement support for dynamic type mapping by merging user-defined type maps with the default SQLite type map.

This update improves JSON handling, extends test coverage, and adds flexibility for overriding type mappings.

Author: dan-sherwin

e2e_sqlite_test.go

@@ -53,7 +53,8 @@ func TestEndToEndSQLite(t *testing.T) {
 			ts_col TIMESTAMP,
 			numeric_col NUMERIC,
 			decimal_col DECIMAL,
-			duration_col DURATION
+			duration_col DURATION,
+			json_col JSONB
 		);`,
 		// second table to exercise relation via ExtraFields (one-to-many)
 		`CREATE TABLE IF NOT EXISTS child (
@@ -172,19 +173,22 @@ Sqlitedbpath = %q
 import (
   "fmt"
   "time"
+  "gorm.io/datatypes"
   g "%s/%s"
   m "%s/%s/models"
 )
 func main(){
   g.DbInit(%q)
   // Insert
-  a := &m.%s{BoolCol: ptrBool(true), Tiny1: ptrStr("1"), IntCol: ptrI64(42), BigCol: ptrI64(4200), RealCol: ptrF64(1.5), DoubleCol: ptrF64(2.5), FloatCol: ptrF32(3.5), TextCol: ptrStr("hello"), VarcharCol: ptrStr("v"), CharCol: ptrStr("c"), BlobCol: ptrBytes([]byte{1,2,3}), DateCol: ptrTime(1700000000), DatetimeCol: ptrTime(1700000100), TsCol: ptrTime(1700000200), NumericCol: ptrF64(10.5), DecimalCol: ptrF64(20.5), DurationCol: ptrDur(1234567890)}
+  js := datatypes.JSONMap(map[string]any{"a": 1, "b": 2})
+  a := &m.%s{BoolCol: ptrBool(true), Tiny1: ptrStr("1"), IntCol: ptrI64(42), BigCol: ptrI64(4200), RealCol: ptrF64(1.5), DoubleCol: ptrF64(2.5), FloatCol: ptrF32(3.5), TextCol: ptrStr("hello"), VarcharCol: ptrStr("v"), CharCol: ptrStr("c"), BlobCol: ptrBytes([]byte{1,2,3}), DateCol: ptrTime(1700000000), DatetimeCol: ptrTime(1700000100), TsCol: ptrTime(1700000200), NumericCol: ptrF64(10.5), DecimalCol: ptrF64(20.5), DurationCol: ptrDur(1234567890), JSONCol: &js}
   if err := g.DB.Create(a).Error; err != nil { panic(err) }
   // Read
   var got m.%s
   if err := g.DB.First(&got, a.ID).Error; err != nil { panic(err) }
   // Update each field
   b := false
+  jsu := datatypes.JSONMap(map[string]any{"c": 3, "d": 4})
   if err := g.DB.Model(&got).Updates(map[string]any{
     "bool_col": &b,
     "tiny1": ptrStr("0"),
@@ -203,6 +207,7 @@ func main(){
     "numeric_col": ptrF64(11.5),
     "decimal_col": ptrF64(21.5),
     "duration_col": ptrDur(987654321),
+    "json_col": &jsu,
   }).Error; err != nil { panic(err) }
   var after m.%s
   if err := g.DB.First(&after, a.ID).Error; err != nil { panic(err) }

sqlite.go

@@ -44,7 +44,11 @@ func sqliteToGorm(cfg ConversionConfig) {
 	// JSON tag strategy same as Postgres generator
 	g.WithJSONTagNameStrategy(func(col string) (tag string) { return strcase.ToLowerCamel(col) })
 	// Use SQLite-specific type map (no Postgres materialized views handling)
-	g.WithDataTypeMap(sqlitetype.TypeMap)
+	dtMaps := sqlitetype.TypeMap
+	for k, v := range cfg.TypeMap {
+		dtMaps[k] = func(columnType gorm.ColumnType) string { return v }
+	}
+	g.WithDataTypeMap(dtMaps)
 	g.WithImportPkgPath("gorm.io/datatypes")
 	g.UseDB(db)
 

sqlitetype/sqlitetype.go

@@ -48,8 +48,8 @@ var TypeMap = map[string]func(gorm.ColumnType) string{
 	"CHAR":    func(ct gorm.ColumnType) string { n, _ := ct.Nullable(); return nullablePtr(n, "string") },
 	"CLOB":    func(ct gorm.ColumnType) string { n, _ := ct.Nullable(); return nullablePtr(n, "string") },
 	"UUID":    func(ct gorm.ColumnType) string { return "datatypes.UUID" },
-	"JSON":    func(ct gorm.ColumnType) string { return "datatypes.JSON" },
-	"JSONB":   func(ct gorm.ColumnType) string { return "datatypes.JSON" },
+	"JSON":    func(ct gorm.ColumnType) string { return "datatypes.JSONMap" },
+	"JSONB":   func(ct gorm.ColumnType) string { return "datatypes.JSONMap" },
 
 	// ---- bytes ----
 	"BLOB": func(gorm.ColumnType) string { return "[]byte" },