Do not store user projects as organization projects (#23353)

A part of https://github.com/go-gitea/gitea/pull/22865

At first, I think we do not need 3 ProjectTypes, as we can check user
type, but it seems that it is not database friendly.

---------

Co-authored-by: delvh <dev.lh@web.de>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: 6543 <6543@obermui.de>

models/migrations/migrations.go

@@ -471,6 +471,8 @@ var migrations = []Migration{
 	NewMigration("Rename Webhook org_id to owner_id", v1_20.RenameWebhookOrgToOwner),
 	// v246 -> v247
 	NewMigration("Add missed column owner_id for project table", v1_20.AddNewColumnForProject),
+	// v247 -> v248
+	NewMigration("Fix incorrect project type", v1_20.FixIncorrectProjectType),
 }
 
 // GetCurrentDBVersion returns the current db version

models/migrations/v1_20/v247.go

@@ -0,0 +1,50 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package v1_20 //nolint
+
+import (
+	"code.gitea.io/gitea/modules/log"
+
+	"xorm.io/xorm"
+)
+
+// FixIncorrectProjectType: set individual project's type from 3(TypeOrganization) to 1(TypeIndividual)
+func FixIncorrectProjectType(x *xorm.Engine) error {
+	type User struct {
+		ID   int64 `xorm:"pk autoincr"`
+		Type int
+	}
+
+	const (
+		UserTypeIndividual int = 0
+
+		TypeIndividual   uint8 = 1
+		TypeOrganization uint8 = 3
+	)
+
+	type Project struct {
+		OwnerID int64 `xorm:"INDEX"`
+		Type    uint8
+		Owner   *User `xorm:"extends"`
+	}
+
+	sess := x.NewSession()
+	defer sess.Close()
+
+	if err := sess.Begin(); err != nil {
+		return err
+	}
+
+	count, err := sess.Table("project").
+		Where("type = ? AND owner_id IN (SELECT id FROM `user` WHERE type = ?)", TypeOrganization, UserTypeIndividual).
+		Update(&Project{
+			Type: TypeIndividual,
+		})
+	if err != nil {
+		return err
+	}
+	log.Debug("Updated %d projects to belong to a user instead of an organization", count)
+
+	return sess.Commit()
+}