Add unique index for project_issue to prevent duplicate data (#30190)

Fix #27639

models/migrations/v1_23/v294.go

@@ -0,0 +1,53 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package v1_23 //nolint
+
+import (
+	"fmt"
+
+	"xorm.io/xorm"
+	"xorm.io/xorm/schemas"
+)
+
+// AddUniqueIndexForProjectIssue adds unique indexes for project issue table
+func AddUniqueIndexForProjectIssue(x *xorm.Engine) error {
+	// remove possible duplicated records in table project_issue
+	type result struct {
+		IssueID   int64
+		ProjectID int64
+		Cnt       int
+	}
+	var results []result
+	if err := x.Select("issue_id, project_id, count(*) as cnt").
+		Table("project_issue").
+		GroupBy("issue_id, project_id").
+		Having("count(*) > 1").
+		Find(&results); err != nil {
+		return err
+	}
+	for _, r := range results {
+		if x.Dialect().URI().DBType == schemas.MSSQL {
+			if _, err := x.Exec(fmt.Sprintf("delete from project_issue where id in (SELECT top %d id FROM project_issue WHERE issue_id = ? and project_id = ?)", r.Cnt-1), r.IssueID, r.ProjectID); err != nil {
+				return err
+			}
+		} else {
+			var ids []int64
+			if err := x.SQL("SELECT id FROM project_issue WHERE issue_id = ? and project_id = ? limit ?", r.IssueID, r.ProjectID, r.Cnt-1).Find(&ids); err != nil {
+				return err
+			}
+			if _, err := x.Table("project_issue").In("id", ids).Delete(); err != nil {
+				return err
+			}
+		}
+	}
+
+	// add unique index for project_issue table
+	type ProjectIssue struct { //revive:disable-line:exported
+		ID        int64 `xorm:"pk autoincr"`
+		IssueID   int64 `xorm:"INDEX unique(s)"`
+		ProjectID int64 `xorm:"INDEX unique(s)"`
+	}
+
+	return x.Sync(new(ProjectIssue))
+}