Add softdelete feature

engine.go

@@ -45,6 +45,7 @@ type Engine struct {
 	TZLocation *time.Location
 
 	disableGlobalCache bool
+	unscoped           bool
 }
 
 func (engine *Engine) SetDisableGlobalCache(disable bool) {
@@ -796,6 +797,8 @@ func (engine *Engine) mapType(v reflect.Value) *core.Table {
 						if !hasNoCacheTag {
 							hasNoCacheTag = true
 						}
+					case k == "SOFTDELETE":
+						col.IsSoftDelete = true
 					case k == "NOT":
 					default:
 						if strings.HasPrefix(k, "'") && strings.HasSuffix(k, "'") {
@@ -1414,3 +1417,9 @@ func (engine *Engine) FormatTime(sqlTypeName string, t time.Time) (v interface{}
 	}
 	return
 }
+
+// Disable soft delete
+func (engine *Engine) Unscoped() *Engine {
+	engine.unscoped = true
+	return engine
+}

session.go

@@ -3402,13 +3402,39 @@ func (session *Session) Delete(bean interface{}) (int64, error) {
 		return 0, ErrNeedDeletedCond
 	}
 
-	sqlStr := fmt.Sprintf("DELETE FROM %v WHERE %v",
-		session.Engine.Quote(session.Statement.TableName()), condition)
+	sqlStr, sqlStrForCache := "", ""
+	argsForCache := make([]interface{}, 0, len(args) * 2)
+	if session.Engine.unscoped || table.SoftDeleteColumn() == nil { // softdelete is disabled
+		sqlStr = fmt.Sprintf("DELETE FROM %v WHERE %v",
+			session.Engine.Quote(session.Statement.TableName()), condition)
+
+		sqlStrForCache = sqlStr
+		copy(argsForCache, args)
+		argsForCache = append(session.Statement.Params, argsForCache...)
+	} else {
+		// !oinume! sqlStrForCache and argsForCache is needed to behave as executing "DELETE FROM ..." for cache.
+		sqlStrForCache = fmt.Sprintf("DELETE FROM %v WHERE %v",
+			session.Engine.Quote(session.Statement.TableName()), condition)
+		copy(argsForCache, args)
+		argsForCache = append(session.Statement.Params, argsForCache...)
+
+		softDeleteCol := table.SoftDeleteColumn()
+		sqlStr = fmt.Sprintf("UPDATE %v SET %v = ? WHERE %v",
+			session.Engine.Quote(session.Statement.TableName()),
+			session.Engine.Quote(softDeleteCol.Name),
+			condition)
+
+		// !oinume! Insert NowTime to the head of session.Statement.Params
+		session.Statement.Params = append(session.Statement.Params, "")
+		paramsLen := len(session.Statement.Params)
+		copy(session.Statement.Params[1:paramsLen], session.Statement.Params[0:paramsLen-1])
+		session.Statement.Params[0] = session.Engine.NowTime(softDeleteCol.SQLType.Name)
+	}
 
 	args = append(session.Statement.Params, args...)
 
 	if cacher := session.Engine.getCacher2(session.Statement.RefTable); cacher != nil && session.Statement.UseCache {
-		session.cacheDelete(sqlStr, args...)
+		session.cacheDelete(sqlStrForCache, argsForCache...)
 	}
 
 	res, err := session.exec(sqlStr, args...)
@@ -3651,6 +3677,10 @@ func genCols(table *core.Table, session *Session, bean interface{}, useCol bool,
 			}
 		}
 
+		if col.IsSoftDelete {
+			continue
+		}
+
 		if session.Statement.ColumnStr != "" {
 			if _, ok := session.Statement.columnMap[lColName]; !ok {
 				continue

statement.go

@@ -286,6 +286,9 @@ func buildUpdates(engine *Engine, table *core.Table, bean interface{},
 		if !includeAutoIncr && col.IsAutoIncrement {
 			continue
 		}
+		if col.IsSoftDelete {
+			continue
+		}
 
 		if engine.dialect.DBType() == core.MSSQL && col.SQLType.Name == core.Text {
 			continue
@@ -490,6 +493,10 @@ func buildConditions(engine *Engine, table *core.Table, bean interface{},
 			continue
 		}
 
+		if col.IsSoftDelete && !engine.unscoped { // softdelete enabled
+			colNames = append(colNames, fmt.Sprintf("%v IS NULL", engine.Quote(col.Name)))
+		}
+
 		fieldValue := *fieldValuePtr
 		if fieldValue.Interface() == nil {
 			continue