Bug fix: missing parentheses if expr cond include or condition

Add expr cond test

Author: xwjdsh

builder_test.go

@@ -217,3 +217,12 @@ func TestSubquery(t *testing.T) {
 	assert.EqualValues(t, "SELECT a, b FROM table_a WHERE id=? AND b_id=(SELECT id FROM table_b WHERE b=?)", sql)
 	assert.EqualValues(t, []interface{}{23, "a"}, args)
 }
+
+// https://github.com/go-xorm/xorm/issues/820
+func TestExprCond(t *testing.T) {
+	b := Select("id").From("table1").Where(expr{sql: "a=? OR b=?", args: []interface{}{1, 2}}).Where(Or(Eq{"c": 3}, Eq{"d": 4}))
+	sql, args, err := b.ToSQL()
+	assert.NoError(t, err)
+	assert.EqualValues(t, "SELECT id FROM table1 WHERE (a=? OR b=?) AND (c=? OR d=?)", sql)
+	assert.EqualValues(t, []interface{}{1, 2, 3, 4}, args)
+}

cond_and.go

@@ -25,7 +25,9 @@ func And(conds ...Cond) Cond {
 func (and condAnd) WriteTo(w Writer) error {
 	for i, cond := range and {
 		_, isOr := cond.(condOr)
-		if isOr {
+		_, isExpr := cond.(expr)
+		wrap := isOr || isExpr
+		if wrap {
 			fmt.Fprint(w, "(")
 		}
 
@@ -34,7 +36,7 @@ func (and condAnd) WriteTo(w Writer) error {
 			return err
 		}
 
-		if isOr {
+		if wrap {
 			fmt.Fprint(w, ")")
 		}