dialect/sql: move columns check from codegen to sql package (#3431)

entc/gen/template/dialect/sql/by.tmpl

@@ -10,34 +10,29 @@ in the LICENSE file in the root directory of this source tree.
 // OrderFunc applies an ordering on the sql selector.
 type OrderFunc func(*sql.Selector)
 
-// columnChecker returns a function indicates if the column exists in the given column.
-func columnChecker(table string) func(string) error {
-	checks := map[string]func(string) bool{
-		{{- range $n := $.Nodes }}
-			{{ $n.Package }}.Table: {{ $n.Package }}.ValidColumn,
-		{{- end }}
-	}
-	check, ok := checks[table]
-	if !ok {
-		return func(string) error {
-			return fmt.Errorf("unknown table %q", table)
-		}
-	}
-	return func(column string) error {
-		if !check(column) {
-			return fmt.Errorf("unknown column %q for table %q", column, table)
-		}
-		return nil
-	}
+var (
+	initCheck sync.Once
+	columnCheck sql.ColumnCheck
+)
+
+// columnChecker checks if the column exists in the given table.
+func checkColumn(table, column string) error {
+	initCheck.Do(func() {
+		columnCheck = sql.NewColumnCheck(map[string]func(string) bool{
+			{{- range $n := $.Nodes }}
+				{{ $n.Package }}.Table: {{ $n.Package }}.ValidColumn,
+			{{- end }}
+		})
+	})
+	return columnCheck(table, column)
 }
 {{- end }}
 
 {{ define "dialect/sql/order/func" -}}
 	{{- $f := $.Scope.Func -}}
 	func(s *sql.Selector) {
-		check := columnChecker(s.TableName())
 		for _, f := range fields {
-			if err := check(f); err != nil {
+			if err := checkColumn(s.TableName(), f); err != nil {
 				s.AddError(&ValidationError{Name: f, err: fmt.Errorf("{{ base $.Config.Package }}: %w", err)})
 			}
 			s.OrderBy(sql.{{ $f }}(s.C(f)))
@@ -61,8 +56,7 @@ func columnChecker(table string) func(string) error {
 	{{- $withField := $.Scope.WithField -}}
 	func(s *sql.Selector) string {
 		{{- if $withField }}
-			check := columnChecker(s.TableName())
-			if err := check(field); err != nil {
+			if err := checkColumn(s.TableName(), field); err != nil {
 				s.AddError(&ValidationError{Name: field, err: fmt.Errorf("{{ base $.Config.Package }}: %w", err)})
 				return ""
 			}