added unique id validator error

forms/validators/model.go

@@ -0,0 +1,38 @@
+package validators
+
+import (
+	"database/sql"
+	"errors"
+
+	validation "github.com/go-ozzo/ozzo-validation/v4"
+	"github.com/pocketbase/dbx"
+	"github.com/pocketbase/pocketbase/daos"
+)
+
+// Compare checks whether the provided model id exists.
+//
+// Example:
+//	validation.Field(&form.Id, validation.By(validators.UniqueId(form.dao, tableName)))
+func UniqueId(dao *daos.Dao, tableName string) validation.RuleFunc {
+	return func(value any) error {
+		v, _ := value.(string)
+		if v == "" {
+			return nil // nothing to check
+		}
+
+		var foundId string
+
+		err := dao.DB().
+			Select("id").
+			From(tableName).
+			Where(dbx.HashExp{"id": v}).
+			Limit(1).
+			Row(&foundId)
+
+		if !errors.Is(err, sql.ErrNoRows) || foundId != "" {
+			return validation.NewError("validation_invalid_id", "The model id is invalid or already exists.")
+		}
+
+		return nil
+	}
+}