Fix missing repository id when migrating release attachments (#36389)

This PR fixes missed repo_id on the migration of attachments to Gitea.
It also provides a doctor check to fix the dirty data on the database.

models/migrations/migrations.go

@@ -399,6 +399,7 @@ func prepareMigrationTasks() []*migration {
 
 		newMigration(323, "Add support for actions concurrency", v1_26.AddActionsConcurrency),
 		newMigration(324, "Fix closed milestone completeness for milestones with no issues", v1_26.FixClosedMilestoneCompleteness),
+		newMigration(325, "Fix missed repo_id when migrate attachments", v1_26.FixMissedRepoIDWhenMigrateAttachments),
 	}
 	return preparedMigrations
 }

models/migrations/v1_26/v325.go

@@ -0,0 +1,18 @@
+// Copyright 2026 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package v1_26
+
+import (
+	"xorm.io/xorm"
+)
+
+func FixMissedRepoIDWhenMigrateAttachments(x *xorm.Engine) error {
+	_, err := x.Exec("UPDATE `attachment` SET `repo_id` = (SELECT `repo_id` FROM `issue` WHERE `issue`.`id` = `attachment`.`issue_id`) WHERE `issue_id` > 0 AND (`repo_id` IS NULL OR `repo_id` = 0);")
+	if err != nil {
+		return err
+	}
+
+	_, err = x.Exec("UPDATE `attachment` SET `repo_id` = (SELECT `repo_id` FROM `release` WHERE `release`.`id` = `attachment`.`release_id`) WHERE `release_id` > 0 AND (`repo_id` IS NULL OR `repo_id` = 0);")
+	return err
+}

models/migrations/v1_26/v325_test.go

@@ -0,0 +1,45 @@
+// Copyright 2026 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package v1_26
+
+import (
+	"testing"
+
+	"code.gitea.io/gitea/models/migrations/base"
+	"code.gitea.io/gitea/modules/timeutil"
+
+	"github.com/stretchr/testify/require"
+)
+
+func Test_FixMissedRepoIDWhenMigrateAttachments(t *testing.T) {
+	type Attachment struct {
+		ID            int64  `xorm:"pk autoincr"`
+		UUID          string `xorm:"uuid UNIQUE"`
+		RepoID        int64  `xorm:"INDEX"`           // this should not be zero
+		IssueID       int64  `xorm:"INDEX"`           // maybe zero when creating
+		ReleaseID     int64  `xorm:"INDEX"`           // maybe zero when creating
+		UploaderID    int64  `xorm:"INDEX DEFAULT 0"` // Notice: will be zero before this column added
+		CommentID     int64  `xorm:"INDEX"`
+		Name          string
+		DownloadCount int64              `xorm:"DEFAULT 0"`
+		Size          int64              `xorm:"DEFAULT 0"`
+		CreatedUnix   timeutil.TimeStamp `xorm:"created"`
+	}
+
+	type Issue struct {
+		ID     int64 `xorm:"pk autoincr"`
+		RepoID int64 `xorm:"INDEX"`
+	}
+
+	type Release struct {
+		ID     int64 `xorm:"pk autoincr"`
+		RepoID int64 `xorm:"INDEX"`
+	}
+
+	// Prepare and load the testing database
+	x, deferrable := base.PrepareTestEnv(t, 0, new(Attachment), new(Issue), new(Release))
+	defer deferrable()
+
+	require.NoError(t, FixMissedRepoIDWhenMigrateAttachments(x))
+}