Support Expression for OrderBy clause

clause/expression.go

@@ -21,6 +21,7 @@ type NegationExpressionBuilder interface {
 type Expr struct {
 	SQL                string
 	Vars               []interface{}
+	WithoutParentheses bool
 }
 
 // Build build raw expression
@@ -32,7 +33,7 @@ func (expr Expr) Build(builder Builder) {
 
 	for _, v := range []byte(expr.SQL) {
 		if v == '?' && len(expr.Vars) > idx {
-			if afterParenthesis {
+			if afterParenthesis || expr.WithoutParentheses {
 				if _, ok := expr.Vars[idx].(driver.Valuer); ok {
 					builder.AddVar(builder, expr.Vars[idx])
 				} else {

clause/order_by.go

@@ -8,6 +8,7 @@ type OrderByColumn struct {
 
 type OrderBy struct {
 	Columns    []OrderByColumn
+	Expression Expression
 }
 
 // Name where clause name
@@ -17,6 +18,9 @@ func (orderBy OrderBy) Name() string {
 
 // Build build where clause
 func (orderBy OrderBy) Build(builder Builder) {
+	if orderBy.Expression != nil {
+		orderBy.Expression.Build(builder)
+	} else {
 		for idx, column := range orderBy.Columns {
 			if idx > 0 {
 				builder.WriteByte(',')
@@ -28,6 +32,7 @@ func (orderBy OrderBy) Build(builder Builder) {
 			}
 		}
 	}
+}
 
 // MergeClause merge order by clauses
 func (orderBy OrderBy) MergeClause(clause *Clause) {

clause/order_by_test.go

@@ -39,6 +39,14 @@ func TestOrderBy(t *testing.T) {
 			},
 			"SELECT * FROM `users` ORDER BY `name`", nil,
 		},
+		{
+			[]clause.Interface{
+				clause.Select{}, clause.From{}, clause.OrderBy{
+					Expression: clause.Expr{SQL: "FIELD(id, ?)", Vars: []interface{}{[]int{1, 2, 3}}, WithoutParentheses: true},
+				},
+			},
+			"SELECT * FROM `users` ORDER BY FIELD(id, ?,?,?)", []interface{}{1, 2, 3},
+		},
 	}
 
 	for idx, result := range results {

tests/query_test.go

@@ -12,6 +12,7 @@ import (
 	"time"
 
 	"gorm.io/gorm"
+	"gorm.io/gorm/clause"
 	. "gorm.io/gorm/utils/tests"
 )
 
@@ -659,6 +660,15 @@ func TestOrder(t *testing.T) {
 	if !regexp.MustCompile("SELECT \\* FROM .*users.* ORDER BY age desc,name").MatchString(result.Statement.SQL.String()) {
 		t.Fatalf("Build Order condition, but got %v", result.Statement.SQL.String())
 	}
+
+	stmt := dryDB.Clauses(clause.OrderBy{
+		Expression: clause.Expr{SQL: "FIELD(id,?)", Vars: []interface{}{[]int{1, 2, 3}}, WithoutParentheses: true},
+	}).Find(&User{}).Statement
+
+	explainedSQL := dryDB.Dialector.Explain(stmt.SQL.String(), stmt.Vars...)
+	if !regexp.MustCompile("SELECT \\* FROM .*users.* ORDER BY FIELD\\(id,1,2,3\\)").MatchString(explainedSQL) {
+		t.Fatalf("Build Order condition, but got %v", explainedSQL)
+	}
 }
 
 func TestLimit(t *testing.T) {