Support SQL expression

model_struct.go

@@ -63,56 +63,6 @@ type Relationship struct {
 	JoinTable                   string
 }
 
-func (scope *Scope) generateSqlTag(field *StructField) {
-	var sqlType string
-	structType := field.Struct.Type
-	if structType.Kind() == reflect.Ptr {
-		structType = structType.Elem()
-	}
-	reflectValue := reflect.Indirect(reflect.New(structType))
-	sqlSettings := parseTagSetting(field.Tag.Get("sql"))
-
-	if value, ok := sqlSettings["TYPE"]; ok {
-		sqlType = value
-	}
-
-	additionalType := sqlSettings["NOT NULL"] + " " + sqlSettings["UNIQUE"]
-	if value, ok := sqlSettings["DEFAULT"]; ok {
-		additionalType = additionalType + "DEFAULT " + value
-	}
-
-	if field.IsScanner {
-		var getScannerValue func(reflect.Value)
-		getScannerValue = func(value reflect.Value) {
-			reflectValue = value
-			if _, isScanner := reflect.New(reflectValue.Type()).Interface().(sql.Scanner); isScanner && reflectValue.Kind() == reflect.Struct {
-				getScannerValue(reflectValue.Field(0))
-			}
-		}
-		getScannerValue(reflectValue)
-	}
-
-	if sqlType == "" {
-		var size = 255
-
-		if value, ok := sqlSettings["SIZE"]; ok {
-			size, _ = strconv.Atoi(value)
-		}
-
-		if field.IsPrimaryKey {
-			sqlType = scope.Dialect().PrimaryKeyTag(reflectValue, size)
-		} else {
-			sqlType = scope.Dialect().SqlTag(reflectValue, size)
-		}
-	}
-
-	if strings.TrimSpace(additionalType) == "" {
-		field.SqlTag = sqlType
-	} else {
-		field.SqlTag = fmt.Sprintf("%v %v", sqlType, additionalType)
-	}
-}
-
 var pluralMapKeys = []*regexp.Regexp{regexp.MustCompile("ch$"), regexp.MustCompile("ss$"), regexp.MustCompile("sh$"), regexp.MustCompile("day$"), regexp.MustCompile("y$"), regexp.MustCompile("x$"), regexp.MustCompile("([^s])s?$")}
 var pluralMapValues = []string{"ches", "sses", "shes", "days", "ies", "xes", "${1}s"}
 
@@ -341,3 +291,68 @@ func (scope *Scope) GetModelStruct(noRelationship ...bool) *ModelStruct {
 func (scope *Scope) GetStructFields() (fields []*StructField) {
 	return scope.GetModelStruct().StructFields
 }
+
+func (scope *Scope) generateSqlTag(field *StructField) {
+	var sqlType string
+	structType := field.Struct.Type
+	if structType.Kind() == reflect.Ptr {
+		structType = structType.Elem()
+	}
+	reflectValue := reflect.Indirect(reflect.New(structType))
+	sqlSettings := parseTagSetting(field.Tag.Get("sql"))
+
+	if value, ok := sqlSettings["TYPE"]; ok {
+		sqlType = value
+	}
+
+	additionalType := sqlSettings["NOT NULL"] + " " + sqlSettings["UNIQUE"]
+	if value, ok := sqlSettings["DEFAULT"]; ok {
+		additionalType = additionalType + "DEFAULT " + value
+	}
+
+	if field.IsScanner {
+		var getScannerValue func(reflect.Value)
+		getScannerValue = func(value reflect.Value) {
+			reflectValue = value
+			if _, isScanner := reflect.New(reflectValue.Type()).Interface().(sql.Scanner); isScanner && reflectValue.Kind() == reflect.Struct {
+				getScannerValue(reflectValue.Field(0))
+			}
+		}
+		getScannerValue(reflectValue)
+	}
+
+	if sqlType == "" {
+		var size = 255
+
+		if value, ok := sqlSettings["SIZE"]; ok {
+			size, _ = strconv.Atoi(value)
+		}
+
+		if field.IsPrimaryKey {
+			sqlType = scope.Dialect().PrimaryKeyTag(reflectValue, size)
+		} else {
+			sqlType = scope.Dialect().SqlTag(reflectValue, size)
+		}
+	}
+
+	if strings.TrimSpace(additionalType) == "" {
+		field.SqlTag = sqlType
+	} else {
+		field.SqlTag = fmt.Sprintf("%v %v", sqlType, additionalType)
+	}
+}
+
+func parseTagSetting(str string) map[string]string {
+	tags := strings.Split(str, ";")
+	setting := map[string]string{}
+	for _, value := range tags {
+		v := strings.Split(value, ":")
+		k := strings.TrimSpace(strings.ToUpper(v[0]))
+		if len(v) == 2 {
+			setting[k] = v[1]
+		} else {
+			setting[k] = k
+		}
+	}
+	return setting
+}

scope.go

@@ -204,8 +204,16 @@ func (scope *Scope) CallMethodWithErrorCheck(name string) {
 
 // AddToVars add value as sql's vars, gorm will escape them
 func (scope *Scope) AddToVars(value interface{}) string {
-	scope.SqlVars = append(scope.SqlVars, value)
-	return scope.Dialect().BinVar(len(scope.SqlVars))
+	if expr, ok := value.(*expr); ok {
+		exp := expr.expr
+		for _, arg := range expr.args {
+			exp = strings.Replace(exp, "?", scope.AddToVars(arg), 1)
+		}
+		return exp
+	} else {
+		scope.SqlVars = append(scope.SqlVars, value)
+		return scope.Dialect().BinVar(len(scope.SqlVars))
+	}
 }
 
 // TableName get table name

scope_private.go

@@ -307,17 +307,31 @@ func (scope *Scope) updatedAttrsWithValues(values map[string]interface{}, ignore
 		return values, true
 	}
 
+	var hasExpr bool
 	fields := scope.Fields()
 	for key, value := range values {
 		if field, ok := fields[ToDBName(key)]; ok && field.Field.IsValid() {
 			if !reflect.DeepEqual(field.Field, reflect.ValueOf(value)) {
-				if !equalAsString(field.Field.Interface(), value) {
+				if _, ok := value.(*expr); ok {
+					hasExpr = true
+				} else if !equalAsString(field.Field.Interface(), value) {
 					hasUpdate = true
 					field.Set(value)
 				}
 			}
 		}
 	}
+	if hasExpr {
+		var updateMap = map[string]interface{}{}
+		for key, value := range fields {
+			if v, ok := values[key]; ok {
+				updateMap[key] = v
+			} else {
+				updateMap[key] = value.Field.Interface()
+			}
+		}
+		return updateMap, true
+	}
 	return
 }
 

update_test.go

@@ -3,6 +3,8 @@ package gorm_test
 import (
 	"testing"
 	"time"
+
+	"github.com/jinzhu/gorm"
 )
 
 func TestUpdate(t *testing.T) {
@@ -67,6 +69,17 @@ func TestUpdate(t *testing.T) {
 	if count := DB.Model(Product{}).Update("CreatedAt", time.Now().Add(2*time.Hour)).RowsAffected; count != int64(len(products)) {
 		t.Error("RowsAffected should be correct when do batch update")
 	}
+
+	DB.First(&product4, product4.Id)
+	DB.Model(&product4).Update("price", gorm.Expr("price + ? - ?", 100, 50))
+	var product5 Product
+	DB.First(&product5, product4.Id)
+	if product5.Price != product4.Price+100-50 {
+		t.Errorf("Update with expression")
+	}
+	if product5.UpdatedAt.Format(time.RFC3339Nano) == product4.UpdatedAt.Format(time.RFC3339Nano) {
+		t.Errorf("Update with expression should update UpdatedAt")
+	}
 }
 
 func TestUpdateWithNoStdPrimaryKeyAndDefaultValues(t *testing.T) {
@@ -148,6 +161,16 @@ func TestUpdates(t *testing.T) {
 	if DB.First(&Product{}, "code = ?", "product2newcode").RecordNotFound() {
 		t.Errorf("product2's code should be updated")
 	}
+
+	DB.Model(&product4).Updates(map[string]interface{}{"price": gorm.Expr("price + ?", 100)})
+	var product5 Product
+	DB.First(&product5, product4.Id)
+	if product5.Price != product4.Price+100 {
+		t.Errorf("Updates with expression")
+	}
+	if product5.UpdatedAt.Format(time.RFC3339Nano) == product4.UpdatedAt.Format(time.RFC3339Nano) {
+		t.Errorf("Updates with expression should update UpdatedAt")
+	}
 }
 
 func TestUpdateColumn(t *testing.T) {
@@ -172,4 +195,14 @@ func TestUpdateColumn(t *testing.T) {
 	if updatedAt2.Format(time.RFC3339Nano) != product4.UpdatedAt.Format(time.RFC3339Nano) {
 		t.Errorf("updatedAt should not be updated with update column")
 	}
+
+	DB.Model(&product4).UpdateColumn("price", gorm.Expr("price + 100 - 50"))
+	var product5 Product
+	DB.First(&product5, product4.Id)
+	if product5.Price != product4.Price+100-50 {
+		t.Errorf("UpdateColumn with expression")
+	}
+	if product5.UpdatedAt.Format(time.RFC3339Nano) != product4.UpdatedAt.Format(time.RFC3339Nano) {
+		t.Errorf("UpdateColumn with expression should not update UpdatedAt")
+	}
 }

utils.go

@@ -38,17 +38,11 @@ func ToDBName(name string) string {
 	return s
 }
 
-func parseTagSetting(str string) map[string]string {
-	tags := strings.Split(str, ";")
-	setting := map[string]string{}
-	for _, value := range tags {
-		v := strings.Split(value, ":")
-		k := strings.TrimSpace(strings.ToUpper(v[0]))
-		if len(v) == 2 {
-			setting[k] = v[1]
-		} else {
-			setting[k] = k
-		}
-	}
-	return setting
+type expr struct {
+	expr string
+	args []interface{}
+}
+
+func Expr(expression string, args ...interface{}) *expr {
+	return &expr{expr: expression, args: args}
 }