feat(reflection): ✨ add tests for standard SQL null types

* Implement tests for mapping standard library sql.Null* types to struct.
* Verify handling of valid and nil values for sql.NullInt64, sql.NullString, sql.NullFloat64, sql.NullBool, and sql.NullTime.
* Ensure correct error handling and type conversion in MapToStruct function.

pkg/reflection/model_utils.go

@@ -1102,6 +1102,12 @@ func setFieldValue(field reflect.Value, value interface{}) error {
 		}
 	}
 
+	// If we can convert the type, do it
+	if valueReflect.Type().ConvertibleTo(field.Type()) {
+		field.Set(valueReflect.Convert(field.Type()))
+		return nil
+	}
+
 	// Handle struct types (like SqlTimeStamp, SqlDate, SqlTime which wrap SqlNull[time.Time])
 	if field.Kind() == reflect.Struct {
 
@@ -1113,9 +1119,9 @@ func setFieldValue(field reflect.Value, value interface{}) error {
 				// Call the Scan method with the value
 				results := scanMethod.Call([]reflect.Value{reflect.ValueOf(value)})
 				if len(results) > 0 {
-					// Check if there was an error
-					if err, ok := results[0].Interface().(error); ok && err != nil {
-						return err
+					// The Scan method returns error - check if it's nil
+					if !results[0].IsNil() {
+						return results[0].Interface().(error)
 					}
 					return nil
 				}
@@ -1170,12 +1176,6 @@ func setFieldValue(field reflect.Value, value interface{}) error {
 
 	}
 
-	// If we can convert the type, do it
-	if valueReflect.Type().ConvertibleTo(field.Type()) {
-		field.Set(valueReflect.Convert(field.Type()))
-		return nil
-	}
-
 	return fmt.Errorf("cannot convert %v to %v", valueReflect.Type(), field.Type())
 }
 

pkg/reflection/model_utils_stdlib_sqltypes_test.go

@@ -0,0 +1,120 @@
+package reflection_test
+
+import (
+	"database/sql"
+	"testing"
+	"time"
+
+	"github.com/bitechdev/ResolveSpec/pkg/reflection"
+)
+
+func TestMapToStruct_StandardSqlNullTypes(t *testing.T) {
+	// Test model with standard library sql.Null* types
+	type TestModel struct {
+		ID        int64           `bun:"id,pk" json:"id"`
+		Age       sql.NullInt64   `bun:"age" json:"age"`
+		Name      sql.NullString  `bun:"name" json:"name"`
+		Score     sql.NullFloat64 `bun:"score" json:"score"`
+		Active    sql.NullBool    `bun:"active" json:"active"`
+		UpdatedAt sql.NullTime    `bun:"updated_at" json:"updated_at"`
+	}
+
+	now := time.Now()
+	dataMap := map[string]any{
+		"id":         int64(100),
+		"age":        int64(25),
+		"name":       "John Doe",
+		"score":      95.5,
+		"active":     true,
+		"updated_at": now,
+	}
+
+	var result TestModel
+	err := reflection.MapToStruct(dataMap, &result)
+	if err != nil {
+		t.Fatalf("MapToStruct() error = %v", err)
+	}
+
+	// Verify ID
+	if result.ID != 100 {
+		t.Errorf("ID = %v, want 100", result.ID)
+	}
+
+	// Verify Age (sql.NullInt64)
+	if !result.Age.Valid {
+		t.Error("Age.Valid = false, want true")
+	}
+	if result.Age.Int64 != 25 {
+		t.Errorf("Age.Int64 = %v, want 25", result.Age.Int64)
+	}
+
+	// Verify Name (sql.NullString)
+	if !result.Name.Valid {
+		t.Error("Name.Valid = false, want true")
+	}
+	if result.Name.String != "John Doe" {
+		t.Errorf("Name.String = %v, want 'John Doe'", result.Name.String)
+	}
+
+	// Verify Score (sql.NullFloat64)
+	if !result.Score.Valid {
+		t.Error("Score.Valid = false, want true")
+	}
+	if result.Score.Float64 != 95.5 {
+		t.Errorf("Score.Float64 = %v, want 95.5", result.Score.Float64)
+	}
+
+	// Verify Active (sql.NullBool)
+	if !result.Active.Valid {
+		t.Error("Active.Valid = false, want true")
+	}
+	if !result.Active.Bool {
+		t.Error("Active.Bool = false, want true")
+	}
+
+	// Verify UpdatedAt (sql.NullTime)
+	if !result.UpdatedAt.Valid {
+		t.Error("UpdatedAt.Valid = false, want true")
+	}
+	if !result.UpdatedAt.Time.Equal(now) {
+		t.Errorf("UpdatedAt.Time = %v, want %v", result.UpdatedAt.Time, now)
+	}
+
+	t.Log("All standard library sql.Null* types handled correctly!")
+}
+
+func TestMapToStruct_StandardSqlNullTypes_WithNil(t *testing.T) {
+	// Test nil handling for standard library sql.Null* types
+	type TestModel struct {
+		ID   int64          `bun:"id,pk" json:"id"`
+		Age  sql.NullInt64  `bun:"age" json:"age"`
+		Name sql.NullString `bun:"name" json:"name"`
+	}
+
+	dataMap := map[string]any{
+		"id":   int64(200),
+		"age":  int64(30),
+		"name": nil, // Explicitly nil
+	}
+
+	var result TestModel
+	err := reflection.MapToStruct(dataMap, &result)
+	if err != nil {
+		t.Fatalf("MapToStruct() error = %v", err)
+	}
+
+	// Age should be valid
+	if !result.Age.Valid {
+		t.Error("Age.Valid = false, want true")
+	}
+	if result.Age.Int64 != 30 {
+		t.Errorf("Age.Int64 = %v, want 30", result.Age.Int64)
+	}
+
+	// Name should be invalid (null)
+	if result.Name.Valid {
+		t.Error("Name.Valid = true, want false (null)")
+	}
+
+	t.Log("Nil handling for sql.Null* types works correctly!")
+}