Added feature to update with null for non pointer value

engine.go

@@ -553,6 +553,13 @@ func (engine *Engine) Omit(columns ...string) *Session {
 	return session.Omit(columns...)
 }
 
+// Set null when column is zero-value and nullable for update
+func (engine *Engine) Nullable(columns ...string) *Session {
+	session := engine.NewSession()
+	session.IsAutoClose = true
+	return session.Nullable(columns...)
+}
+
 // This method will generate "column IN (?, ?)"
 func (engine *Engine) In(column string, args ...interface{}) *Session {
 	session := engine.NewSession()

helpers.go

@@ -39,6 +39,8 @@ func isZero(k interface{}) bool {
 		return k.(uint64) == 0
 	case string:
 		return k.(string) == ""
+	case time.Time:
+		return k.(time.Time).IsZero()
 	}
 	return false
 }
@@ -356,6 +358,14 @@ func genCols(table *core.Table, session *Session, bean interface{}, useCol bool,
 			}
 		}
 
+		// !evalphobia! set fieldValue as nil when column is nullable and zero-value
+		if _, ok := session.Statement.nullableMap[lColName]; ok {
+			if col.Nullable && isZero(fieldValue.Interface()) {
+				var nilValue *int
+				fieldValue = reflect.ValueOf(nilValue)
+			}
+		}
+
 		if (col.IsCreated || col.IsUpdated) && session.Statement.UseAutoTime {
 			val, t := session.Engine.NowTime2(col.SQLType.Name)
 			args = append(args, val)

session.go

@@ -223,6 +223,12 @@ func (session *Session) Omit(columns ...string) *Session {
 	return session
 }
 
+// Set null when column is zero-value and nullable for update
+func (session *Session) Nullable(columns ...string) *Session {
+	session.Statement.Nullable(columns...)
+	return session
+}
+
 // Method NoAutoTime means do not automatically give created field and updated field
 // the current time on the current session temporarily
 func (session *Session) NoAutoTime() *Session {
@@ -3408,7 +3414,8 @@ func (session *Session) Update(bean interface{}, condiBean ...interface{}) (int6
 		if session.Statement.ColumnStr == "" {
 			colNames, args = buildUpdates(session.Engine, table, bean, false, false,
 				false, false, session.Statement.allUseBool, session.Statement.useAllCols,
-				session.Statement.mustColumnMap, session.Statement.columnMap, true)
+				session.Statement.mustColumnMap, session.Statement.nullableMap, 
+				session.Statement.columnMap, true)
 		} else {
 			colNames, args, err = genCols(table, session, bean, true, true)
 			if err != nil {

statement.go

@@ -70,6 +70,7 @@ type Statement struct {
 	checkVersion  bool
 	unscoped      bool
 	mustColumnMap map[string]bool
+	nullableMap   map[string]bool
 	inColumns     map[string]*inParam
 	incrColumns   map[string]incrParam
 	decrColumns   map[string]decrParam
@@ -105,6 +106,7 @@ func (statement *Statement) Init() {
 	statement.allUseBool = false
 	statement.useAllCols = false
 	statement.mustColumnMap = make(map[string]bool)
+	statement.nullableMap = make(map[string]bool)
 	statement.checkVersion = true
 	statement.unscoped = false
 	statement.inColumns = make(map[string]*inParam)
@@ -176,7 +178,8 @@ func (statement *Statement) Table(tableNameOrBean interface{}) *Statement {
 func buildUpdates(engine *Engine, table *core.Table, bean interface{},
 	includeVersion bool, includeUpdated bool, includeNil bool,
 	includeAutoIncr bool, allUseBool bool, useAllCols bool,
-	mustColumnMap map[string]bool, columnMap map[string]bool, update bool) ([]string, []interface{}) {
+	mustColumnMap map[string]bool, nullableMap map[string]bool,
+	columnMap map[string]bool, update bool) ([]string, []interface{}) {
 
 	colNames := make([]string, 0)
 	var args = make([]interface{}, 0)
@@ -215,7 +218,8 @@ func buildUpdates(engine *Engine, table *core.Table, bean interface{},
 
 		requiredField := useAllCols
 		includeNil := useAllCols
-		if b, ok := mustColumnMap[strings.ToLower(col.Name)]; ok {
+		lColName := strings.ToLower(col.Name)
+		if b, ok := mustColumnMap[lColName]; ok {
 			if b {
 				requiredField = true
 			} else {
@@ -223,6 +227,16 @@ func buildUpdates(engine *Engine, table *core.Table, bean interface{},
 			}
 		}
 
+		// !evalphobia! set fieldValue as nil when column is nullable and zero-value
+		if b, ok := nullableMap[lColName]; ok {
+			if b && col.Nullable && isZero(fieldValue.Interface()) {
+				var nilValue *int
+				fieldValue = reflect.ValueOf(nilValue)
+				fieldType = reflect.TypeOf(fieldValue.Interface())
+				includeNil = true
+			}
+		}
+
 		var val interface{}
 
 		if fieldValue.CanAddr() {
@@ -818,6 +832,14 @@ func (statement *Statement) Omit(columns ...string) {
 	statement.OmitStr = statement.Engine.Quote(strings.Join(newColumns, statement.Engine.Quote(", ")))
 }
 
+// Update use only: update columns to null when value is nullable and zero-value
+func (statement *Statement) Nullable(columns ...string) {
+	newColumns := col2NewCols(columns...)
+	for _, nc := range newColumns {
+		statement.nullableMap[strings.ToLower(nc)] = true
+	}
+}
+
 // Generate LIMIT limit statement
 func (statement *Statement) Top(limit int) *Statement {
 	statement.Limit(limit)