diff --git a/app/repository/smartfilter/filters.go b/app/repository/smartfilter/filters.go
new file mode 100644
index 0000000..39a6acd
--- /dev/null
+++ b/app/repository/smartfilter/filters.go
@@ -0,0 +1,51 @@
+package smartfilter
+
+import (
+	"fmt"
+
+	"gorm.io/gorm"
+)
+
+func applyFilterEQ[T bool | int64 | uint64 | float64 | string](
+	query *gorm.DB, tableName string, filterField *FilterField, value T,
+) *gorm.DB {
+	return query.Where(fmt.Sprintf("%s.%s = ?", tableName, filterField.Name), value)
+}
+
+func applyFilterNE[T bool | int64 | uint64 | float64 | string](
+	query *gorm.DB, tableName string, filterField *FilterField, value T,
+) *gorm.DB {
+	return query.Where(fmt.Sprintf("%s.%s != ?", tableName, filterField.Name), value)
+}
+
+func applyFilterLIKE(query *gorm.DB, tableName string, filterField *FilterField, value string) *gorm.DB {
+	return query.Where(fmt.Sprintf("%s.%s LIKE ?", tableName, filterField.Name), fmt.Sprintf("%%%s%%", value))
+}
+
+func applyFilterILIKE(query *gorm.DB, tableName string, filterField *FilterField, value string) *gorm.DB {
+	return query.Where(fmt.Sprintf("%s.%s ILIKE ?", tableName, filterField.Name), fmt.Sprintf("%%%s%%", value))
+}
+
+func applyFilterGT[T bool | int64 | uint64 | float64 | string](
+	query *gorm.DB, tableName string, filterField *FilterField, value T,
+) *gorm.DB {
+	return query.Where(fmt.Sprintf("%s.%s > ?", tableName, filterField.Name), value)
+}
+
+func applyFilterGE[T bool | int64 | uint64 | float64 | string](
+	query *gorm.DB, tableName string, filterField *FilterField, value T,
+) *gorm.DB {
+	return query.Where(fmt.Sprintf("%s.%s >= ?", tableName, filterField.Name), value)
+}
+
+func applyFilterLT[T bool | int64 | uint64 | float64 | string](
+	query *gorm.DB, tableName string, filterField *FilterField, value T,
+) *gorm.DB {
+	return query.Where(fmt.Sprintf("%s.%s < ?", tableName, filterField.Name), value)
+}
+
+func applyFilterLE[T bool | int64 | uint64 | float64 | string](
+	query *gorm.DB, tableName string, filterField *FilterField, value T,
+) *gorm.DB {
+	return query.Where(fmt.Sprintf("%s.%s <= ?", tableName, filterField.Name), value)
+}
diff --git a/app/repository/smartfilter/smartfilter.go b/app/repository/smartfilter/smartfilter.go
index 04f4b05..cf87c7d 100644
--- a/app/repository/smartfilter/smartfilter.go
+++ b/app/repository/smartfilter/smartfilter.go
@@ -14,7 +14,7 @@ import (
 const TAG_NAME = "filterfield"
 const TAG_VALUE_SEPARATOR = ","
 
-type handlerFunc func(query *gorm.DB, tableName string, filterField *FilterField) (*gorm.DB, error)
+type handlerFunc func(query *gorm.DB, tableName string, filterField *FilterField) *gorm.DB
 
 var operatorHandlers = map[Operator]handlerFunc{
 	OperatorEQ:    handleOperatorEQ,
@@ -80,179 +80,15 @@ func (f SmartCertFilter[T]) ToQuery(query *gorm.DB) (*gorm.DB, error) {
 			return nil, fmt.Errorf("no handler for operator %s", filterField.Operator)
 		}
 
-		query, err = operatorHandler(query, tableName, filterField)
-		if err != nil {
-			return nil, err
+		query = operatorHandler(query, tableName, filterField)
+		if query == nil {
+			return nil, fmt.Errorf("invalid field type for operator %s", filterField.Operator)
 		}
 	}
 
 	return query, nil
 }
 
-func handleOperatorEQ(query *gorm.DB, tableName string, filterField *FilterField) (*gorm.DB, error) {
-	switch filterField.valueKind {
-	case reflect.Bool:
-		query = applyFilterEQ(query, tableName, filterField, *filterField.boolValue)
-	case reflect.Int, reflect.Int16, reflect.Int32, reflect.Int64:
-		query = applyFilterEQ(query, tableName, filterField, *filterField.intValue)
-	case reflect.Uint, reflect.Uint16, reflect.Uint32, reflect.Uint64:
-		query = applyFilterEQ(query, tableName, filterField, *filterField.uintValue)
-	case reflect.Float32, reflect.Float64:
-		query = applyFilterEQ(query, tableName, filterField, *filterField.floatValue)
-	case reflect.String:
-		query = applyFilterEQ(query, tableName, filterField, *filterField.strValue)
-	default:
-		return nil, fmt.Errorf("invalid field type for operator %s", filterField.Operator)
-	}
-	return query, nil
-}
-
-func applyFilterEQ[T bool | int64 | uint64 | float64 | string](
-	query *gorm.DB, tableName string, filterField *FilterField, value T,
-) *gorm.DB {
-	return query.Where(fmt.Sprintf("%s.%s = ?", tableName, filterField.Name), value)
-}
-
-func handleOperatorNE(query *gorm.DB, tableName string, filterField *FilterField) (*gorm.DB, error) {
-	switch filterField.valueKind {
-	case reflect.Bool:
-		query = applyFilterNE(query, tableName, filterField, *filterField.boolValue)
-	case reflect.Int, reflect.Int16, reflect.Int32, reflect.Int64:
-		query = applyFilterNE(query, tableName, filterField, *filterField.intValue)
-	case reflect.Uint, reflect.Uint16, reflect.Uint32, reflect.Uint64:
-		query = applyFilterNE(query, tableName, filterField, *filterField.uintValue)
-	case reflect.Float32, reflect.Float64:
-		query = applyFilterNE(query, tableName, filterField, *filterField.floatValue)
-	case reflect.String:
-		query = applyFilterNE(query, tableName, filterField, *filterField.strValue)
-	default:
-		return nil, fmt.Errorf("invalid field type for operator %s", filterField.Operator)
-	}
-	return query, nil
-}
-
-func applyFilterNE[T bool | int64 | uint64 | float64 | string](
-	query *gorm.DB, tableName string, filterField *FilterField, value T,
-) *gorm.DB {
-	return query.Where(fmt.Sprintf("%s.%s != ?", tableName, filterField.Name), value)
-}
-
-func handleOperatorLIKE(query *gorm.DB, tableName string, filterField *FilterField) (*gorm.DB, error) {
-	switch filterField.valueKind {
-	case reflect.String:
-		query = applyFilterLIKE(query, tableName, filterField, *filterField.strValue)
-	default:
-		return nil, fmt.Errorf("invalid field type for operator %s", filterField.Operator)
-	}
-	return query, nil
-}
-
-func applyFilterLIKE(query *gorm.DB, tableName string, filterField *FilterField, value string) *gorm.DB {
-	return query.Where(fmt.Sprintf("%s.%s LIKE ?", tableName, filterField.Name), fmt.Sprintf("%%%s%%", value))
-}
-
-func handleOperatorILIKE(query *gorm.DB, tableName string, filterField *FilterField) (*gorm.DB, error) {
-	switch filterField.valueKind {
-	case reflect.String:
-		query = applyFilterILIKE(query, tableName, filterField, *filterField.strValue)
-	default:
-		return nil, fmt.Errorf("invalid field type for operator %s", filterField.Operator)
-	}
-	return query, nil
-}
-
-func applyFilterILIKE(query *gorm.DB, tableName string, filterField *FilterField, value string) *gorm.DB {
-	return query.Where(fmt.Sprintf("%s.%s ILIKE ?", tableName, filterField.Name), fmt.Sprintf("%%%s%%", value))
-}
-
-func handleOperatorGT(query *gorm.DB, tableName string, filterField *FilterField) (*gorm.DB, error) {
-	switch filterField.valueKind {
-	case reflect.Int, reflect.Int16, reflect.Int32, reflect.Int64:
-		query = applyFilterGT(query, tableName, filterField, *filterField.intValue)
-	case reflect.Uint, reflect.Uint16, reflect.Uint32, reflect.Uint64:
-		query = applyFilterGT(query, tableName, filterField, *filterField.uintValue)
-	case reflect.Float32, reflect.Float64:
-		query = applyFilterGT(query, tableName, filterField, *filterField.floatValue)
-	case reflect.String:
-		query = applyFilterGT(query, tableName, filterField, *filterField.strValue)
-	default:
-		return nil, fmt.Errorf("invalid field type for operator %s", filterField.Operator)
-	}
-	return query, nil
-}
-
-func applyFilterGT[T bool | int64 | uint64 | float64 | string](
-	query *gorm.DB, tableName string, filterField *FilterField, value T,
-) *gorm.DB {
-	return query.Where(fmt.Sprintf("%s.%s > ?", tableName, filterField.Name), value)
-}
-
-func handleOperatorGE(query *gorm.DB, tableName string, filterField *FilterField) (*gorm.DB, error) {
-	switch filterField.valueKind {
-	case reflect.Int, reflect.Int16, reflect.Int32, reflect.Int64:
-		query = applyFilterGE(query, tableName, filterField, *filterField.intValue)
-	case reflect.Uint, reflect.Uint16, reflect.Uint32, reflect.Uint64:
-		query = applyFilterGE(query, tableName, filterField, *filterField.uintValue)
-	case reflect.Float32, reflect.Float64:
-		query = applyFilterGE(query, tableName, filterField, *filterField.floatValue)
-	case reflect.String:
-		query = applyFilterGE(query, tableName, filterField, *filterField.strValue)
-	default:
-		return nil, fmt.Errorf("invalid field type for operator %s", filterField.Operator)
-	}
-	return query, nil
-}
-
-func applyFilterGE[T bool | int64 | uint64 | float64 | string](
-	query *gorm.DB, tableName string, filterField *FilterField, value T,
-) *gorm.DB {
-	return query.Where(fmt.Sprintf("%s.%s >= ?", tableName, filterField.Name), value)
-}
-
-func handleOperatorLT(query *gorm.DB, tableName string, filterField *FilterField) (*gorm.DB, error) {
-	switch filterField.valueKind {
-	case reflect.Int, reflect.Int16, reflect.Int32, reflect.Int64:
-		query = applyFilterLT(query, tableName, filterField, *filterField.intValue)
-	case reflect.Uint, reflect.Uint16, reflect.Uint32, reflect.Uint64:
-		query = applyFilterLT(query, tableName, filterField, *filterField.uintValue)
-	case reflect.Float32, reflect.Float64:
-		query = applyFilterLT(query, tableName, filterField, *filterField.floatValue)
-	case reflect.String:
-		query = applyFilterLT(query, tableName, filterField, *filterField.strValue)
-	default:
-		return nil, fmt.Errorf("invalid field type for operator %s", filterField.Operator)
-	}
-	return query, nil
-}
-
-func applyFilterLT[T bool | int64 | uint64 | float64 | string](
-	query *gorm.DB, tableName string, filterField *FilterField, value T,
-) *gorm.DB {
-	return query.Where(fmt.Sprintf("%s.%s < ?", tableName, filterField.Name), value)
-}
-
-func handleOperatorLE(query *gorm.DB, tableName string, filterField *FilterField) (*gorm.DB, error) {
-	switch filterField.valueKind {
-	case reflect.Int, reflect.Int16, reflect.Int32, reflect.Int64:
-		query = applyFilterLE(query, tableName, filterField, *filterField.intValue)
-	case reflect.Uint, reflect.Uint16, reflect.Uint32, reflect.Uint64:
-		query = applyFilterLE(query, tableName, filterField, *filterField.uintValue)
-	case reflect.Float32, reflect.Float64:
-		query = applyFilterLE(query, tableName, filterField, *filterField.floatValue)
-	case reflect.String:
-		query = applyFilterLE(query, tableName, filterField, *filterField.strValue)
-	default:
-		return nil, fmt.Errorf("invalid field type for operator %s", filterField.Operator)
-	}
-	return query, nil
-}
-
-func applyFilterLE[T bool | int64 | uint64 | float64 | string](
-	query *gorm.DB, tableName string, filterField *FilterField, value T,
-) *gorm.DB {
-	return query.Where(fmt.Sprintf("%s.%s <= ?", tableName, filterField.Name), value)
-}
-
 func newFilterField(tagValue string) (*FilterField, error) {
 	values := strings.Split(tagValue, TAG_VALUE_SEPARATOR)
 	if len(values) != 2 {
@@ -270,3 +106,107 @@ func newFilterField(tagValue string) (*FilterField, error) {
 	}
 	return &f, nil
 }
+
+func handleOperatorEQ(query *gorm.DB, tableName string, filterField *FilterField) *gorm.DB {
+	switch filterField.valueKind {
+	case reflect.Bool:
+		return applyFilterEQ(query, tableName, filterField, *filterField.boolValue)
+	case reflect.Int, reflect.Int16, reflect.Int32, reflect.Int64:
+		return applyFilterEQ(query, tableName, filterField, *filterField.intValue)
+	case reflect.Uint, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+		return applyFilterEQ(query, tableName, filterField, *filterField.uintValue)
+	case reflect.Float32, reflect.Float64:
+		return applyFilterEQ(query, tableName, filterField, *filterField.floatValue)
+	case reflect.String:
+		return applyFilterEQ(query, tableName, filterField, *filterField.strValue)
+	}
+	return nil
+}
+
+func handleOperatorNE(query *gorm.DB, tableName string, filterField *FilterField) *gorm.DB {
+	switch filterField.valueKind {
+	case reflect.Bool:
+		return applyFilterNE(query, tableName, filterField, *filterField.boolValue)
+	case reflect.Int, reflect.Int16, reflect.Int32, reflect.Int64:
+		return applyFilterNE(query, tableName, filterField, *filterField.intValue)
+	case reflect.Uint, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+		return applyFilterNE(query, tableName, filterField, *filterField.uintValue)
+	case reflect.Float32, reflect.Float64:
+		return applyFilterNE(query, tableName, filterField, *filterField.floatValue)
+	case reflect.String:
+		return applyFilterNE(query, tableName, filterField, *filterField.strValue)
+	}
+	return nil
+}
+
+func handleOperatorLIKE(query *gorm.DB, tableName string, filterField *FilterField) *gorm.DB {
+	switch filterField.valueKind {
+	case reflect.String:
+		return applyFilterLIKE(query, tableName, filterField, *filterField.strValue)
+	}
+	return nil
+}
+
+func handleOperatorILIKE(query *gorm.DB, tableName string, filterField *FilterField) *gorm.DB {
+	switch filterField.valueKind {
+	case reflect.String:
+		return applyFilterILIKE(query, tableName, filterField, *filterField.strValue)
+	}
+	return nil
+}
+
+func handleOperatorGT(query *gorm.DB, tableName string, filterField *FilterField) *gorm.DB {
+	switch filterField.valueKind {
+	case reflect.Int, reflect.Int16, reflect.Int32, reflect.Int64:
+		return applyFilterGT(query, tableName, filterField, *filterField.intValue)
+	case reflect.Uint, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+		return applyFilterGT(query, tableName, filterField, *filterField.uintValue)
+	case reflect.Float32, reflect.Float64:
+		return applyFilterGT(query, tableName, filterField, *filterField.floatValue)
+	case reflect.String:
+		return applyFilterGT(query, tableName, filterField, *filterField.strValue)
+	}
+	return nil
+}
+
+func handleOperatorGE(query *gorm.DB, tableName string, filterField *FilterField) *gorm.DB {
+	switch filterField.valueKind {
+	case reflect.Int, reflect.Int16, reflect.Int32, reflect.Int64:
+		return applyFilterGE(query, tableName, filterField, *filterField.intValue)
+	case reflect.Uint, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+		return applyFilterGE(query, tableName, filterField, *filterField.uintValue)
+	case reflect.Float32, reflect.Float64:
+		return applyFilterGE(query, tableName, filterField, *filterField.floatValue)
+	case reflect.String:
+		return applyFilterGE(query, tableName, filterField, *filterField.strValue)
+	}
+	return nil
+}
+
+func handleOperatorLT(query *gorm.DB, tableName string, filterField *FilterField) *gorm.DB {
+	switch filterField.valueKind {
+	case reflect.Int, reflect.Int16, reflect.Int32, reflect.Int64:
+		return applyFilterLT(query, tableName, filterField, *filterField.intValue)
+	case reflect.Uint, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+		return applyFilterLT(query, tableName, filterField, *filterField.uintValue)
+	case reflect.Float32, reflect.Float64:
+		return applyFilterLT(query, tableName, filterField, *filterField.floatValue)
+	case reflect.String:
+		return applyFilterLT(query, tableName, filterField, *filterField.strValue)
+	}
+	return nil
+}
+
+func handleOperatorLE(query *gorm.DB, tableName string, filterField *FilterField) *gorm.DB {
+	switch filterField.valueKind {
+	case reflect.Int, reflect.Int16, reflect.Int32, reflect.Int64:
+		return applyFilterLE(query, tableName, filterField, *filterField.intValue)
+	case reflect.Uint, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+		return applyFilterLE(query, tableName, filterField, *filterField.uintValue)
+	case reflect.Float32, reflect.Float64:
+		return applyFilterLE(query, tableName, filterField, *filterField.floatValue)
+	case reflect.String:
+		return applyFilterLE(query, tableName, filterField, *filterField.strValue)
+	}
+	return nil
+}