enhance(repo): prefill new issue and pull request sidebars from query parameters (#39804)

Links to the new issue and new pull request pages can preselect sidebar
values with the same query parameters as the issue list filters:
`labels`, `milestone`, `project` and `assignee`, each taking
comma-separated IDs, e.g. `compare/main...branch?labels=1,2&assignee=3`.
Previously, pull requests supported none of them and issues only
`milestone` and `project`. On the compare page they also expand the new
pull request form, like `title` and `body`. Query values take precedence
over issue template labels and assignees.

* Fix https://github.com/go-gitea/gitea/issues/27341

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

modules/base/tool.go

@@ -12,6 +12,7 @@ import (
 	"fmt"
 	"hash"
 	"strconv"
+	"strings"
 	"time"
 
 	"gitea.dev/modules/setting"
@@ -117,3 +118,7 @@ func Int64sToStrings(ints []int64) []string {
 	}
 	return strs
 }
+
+func JoinInt64s(ints []int64, sep string) string {
+	return strings.Join(Int64sToStrings(ints), sep)
+}

routers/web/repo/compare.go

@@ -384,13 +384,16 @@ func (cpi *comparePageInfoType) prepareCompareDiff(ctx *context.Context, whitesp
 	ctx.Data["BeforeCommitID"] = ci.CompareBase
 	ctx.Data["AfterCommitID"] = headCommitID
 
-	// follow GitHub's behavior: autofill the form and expand
 	newPrFormTitle := ctx.FormTrim("title")
 	newPrFormBody := ctx.FormTrim("body")
-	ctx.Data["ExpandNewPrForm"] = ctx.FormBool("expand") || ctx.FormBool("quick_pull") || newPrFormTitle != "" || newPrFormBody != ""
 	ctx.Data["TitleQuery"] = newPrFormTitle
 	ctx.Data["BodyQuery"] = newPrFormBody
 
+	// follow GitHub's behavior: autofill the form and expand
+	prefillParams := issuePrefillQuery(ctx)
+	ctx.Data["ExpandNewPrForm"] = ctx.FormBool("expand") || ctx.FormBool("quick_pull") ||
+		newPrFormTitle != "" || newPrFormBody != "" || prefillParams != ""
+
 	if headCommitID == ci.CompareBase {
 		config := repo.MustGetUnit(ctx, unit.TypePullRequests).PullRequestsConfig()
 		// if auto-detect manual merge, an empty PR will be closed immediately because it is already on base branch
@@ -623,7 +626,7 @@ func (cpi *comparePageInfoType) prepareCreatePullRequestPage(ctx *context.Contex
 
 		if !cpi.nothingToCompare {
 			// Setup information for new form.
-			pageMetaData := retrieveRepoIssueMetaData(ctx, ctx.Repo.Repository, nil, true)
+			pageMetaData := retrieveRepoIssueMetaDataWithPrefill(ctx, ctx.Repo.Repository, true)
 			if ctx.Written() {
 				return
 			}

routers/web/repo/issue_new.go

@@ -75,14 +75,14 @@ func setTemplateIfExists(ctx *context.Context, ctxDataKey string, possibleFiles
 			ctx.Data["TemplateFile"] = template.FileName
 		}
 
-		metaData.LabelsData.SetSelectedLabelNames(template.Labels)
-
-		selectedAssigneeIDStrings := make([]string, 0, len(template.Assignees))
-		selectedAssigneeIDs, _ := user_model.GetDoerUserIDsByNames(ctx, template.Assignees)
-		for _, userID := range selectedAssigneeIDs {
-			selectedAssigneeIDStrings = append(selectedAssigneeIDStrings, strconv.FormatInt(userID, 10))
+		// the query parameters take precedence
+		if metaData.LabelsData.SelectedLabelIDs == "" {
+			metaData.LabelsData.SetSelectedLabelNames(template.Labels)
+		}
+		if metaData.AssigneesData.SelectedAssigneeIDs == "" {
+			selectedAssigneeIDs, _ := user_model.GetDoerUserIDsByNames(ctx, template.Assignees)
+			metaData.AssigneesData.SelectedAssigneeIDs = base.JoinInt64s(selectedAssigneeIDs, ",")
 		}
-		metaData.AssigneesData.SelectedAssigneeIDs = strings.Join(selectedAssigneeIDStrings, ",")
 
 		if template.Ref != "" && !strings.HasPrefix(template.Ref, "refs/") { // Assume that the ref intended is always a branch - for tags users should use refs/tags/<ref>
 			template.Ref = git.BranchPrefix + template.Ref
@@ -114,14 +114,11 @@ func NewIssue(ctx *context.Context) {
 	ctx.Data["IsAttachmentEnabled"] = setting.Attachment.Enabled
 	upload.AddUploadContext(ctx, "comment")
 
-	pageMetaData := retrieveRepoIssueMetaData(ctx, ctx.Repo.Repository, nil, false)
+	pageMetaData := retrieveRepoIssueMetaDataWithPrefill(ctx, ctx.Repo.Repository, false)
 	if ctx.Written() {
 		return
 	}
 
-	pageMetaData.MilestonesData.SelectedMilestoneID = ctx.FormInt64("milestone")
-
-	pageMetaData.SetSelectedProjectIDs(parseProjectIDsFromQuery(ctx))
 	if len(pageMetaData.ProjectsData.SelectedProjectIDs) == 1 {
 		ctx.Data["redirect_after_creation"] = "project"
 	}
@@ -148,7 +145,7 @@ func NewIssue(ctx *context.Context) {
 	ctx.Data["IsIssuePoster"] = true // the current user will be the poster of the new issue
 
 	if !issueConfig.BlankIssuesEnabled && hasTemplates && !templateLoaded {
-		// The "issues/new" and "issues/new/choose" share the same query parameters "project" and "milestone", if blank issues are disabled, just redirect to the "issues/choose" page with these parameters.
+		// The "issues/new" and "issues/new/choose" share the same prefill query parameters, if blank issues are disabled, just redirect to the "issues/choose" page with these parameters.
 		ctx.Redirect(fmt.Sprintf("%s/issues/new/choose?%s", ctx.Repo.Repository.Link(), ctx.Req.URL.RawQuery), http.StatusSeeOther)
 		return
 	}
@@ -193,7 +190,7 @@ func NewIssueChooseTemplate(ctx *context.Context) {
 	}
 
 	if !issue_service.HasTemplatesOrContactLinks(ctx, ctx.Repo.Repository, ctx.Repo.GitRepo) {
-		// The "issues/new" and "issues/new/choose" share the same query parameters "project" and "milestone", if no template here, just redirect to the "issues/new" page with these parameters.
+		// The "issues/new" and "issues/new/choose" share the same prefill query parameters, if no template here, just redirect to the "issues/new" page with these parameters.
 		ctx.Redirect(fmt.Sprintf("%s/issues/new?%s", ctx.Repo.Repository.Link(), ctx.Req.URL.RawQuery), http.StatusSeeOther)
 		return
 	}
@@ -202,8 +199,7 @@ func NewIssueChooseTemplate(ctx *context.Context) {
 	ctx.Data["IssueConfig"] = issueConfig
 	ctx.Data["IssueConfigError"] = err // ctx.Flash.Err makes problems here
 
-	ctx.Data["milestone"] = ctx.FormInt64("milestone")
-	ctx.Data["project"] = ctx.FormInt64("project")
+	ctx.Data["PrefillQuery"] = issuePrefillQuery(ctx)
 
 	ctx.HTML(http.StatusOK, tplIssueChoose)
 }
@@ -236,8 +232,8 @@ func toSet[ItemType any, KeyType comparable](slice []ItemType, keyFunc func(Item
 	return s
 }
 
-// ValidateRepoMetasForNewIssue check and returns repository's meta information
-func ValidateRepoMetasForNewIssue(ctx *context.Context, form forms.CreateIssueForm, isPull bool) (ret struct {
+// ValidateRepoMetasForCreateIssue check and returns repository's meta information
+func ValidateRepoMetasForCreateIssue(ctx *context.Context, form forms.CreateIssueForm, isPull bool) (ret struct {
 	LabelIDs, AssigneeIDs []int64
 	MilestoneID           int64
 	ProjectIDs            []int64
@@ -325,7 +321,7 @@ func NewIssuePost(ctx *context.Context) {
 
 	repo := ctx.Repo.Repository
 
-	validateRet := ValidateRepoMetasForNewIssue(ctx, *form, false)
+	validateRet := ValidateRepoMetasForCreateIssue(ctx, *form, false)
 	if ctx.Written() {
 		return
 	}

routers/web/repo/issue_page_meta.go

@@ -4,6 +4,9 @@
 package repo
 
 import (
+	"html/template"
+	"net/url"
+	"slices"
 	"sort"
 	"strconv"
 	"strings"
@@ -14,6 +17,7 @@ import (
 	project_model "gitea.dev/models/project"
 	repo_model "gitea.dev/models/repo"
 	user_model "gitea.dev/models/user"
+	"gitea.dev/modules/base"
 	"gitea.dev/modules/container"
 	"gitea.dev/modules/optional"
 	shared_user "gitea.dev/routers/web/shared/user"
@@ -129,6 +133,92 @@ func retrieveRepoIssueMetaData(ctx *context.Context, repo *repo_model.Repository
 	return data
 }
 
+const (
+	newIssuePrefillLabelFallback = "labels" // "labels" was introduced long time ago
+	newIssuePrefillLabel         = "label"  // to be consistent with other prefill params, we use "label" instead of "labels"
+	newIssuePrefillMilestone     = "milestone"
+	newIssuePrefillProject       = "project"
+	newIssuePrefillAssignee      = "assignee"
+)
+
+func issuePrefillQuery(ctx *context.Context) template.URL {
+	keys := []string{newIssuePrefillLabel, newIssuePrefillLabelFallback, newIssuePrefillMilestone, newIssuePrefillProject, newIssuePrefillAssignee}
+	query := url.Values{}
+	for _, key := range keys {
+		if value := ctx.FormString(key); value != "" {
+			query.Set(key, value)
+		}
+	}
+	return template.URL(query.Encode())
+}
+
+func makeItemIdNameMap[T any](items []T, getKey func(item T) (int64, string)) map[string]T {
+	m := make(map[string]T)
+	for _, item := range items {
+		id, name := getKey(item)
+		m[strconv.FormatInt(id, 10)] = item
+		lowerName := strings.ToLower(name)
+		if _, exists := m[lowerName]; !exists {
+			m[lowerName] = item
+		}
+	}
+	return m
+}
+
+func pickItemIDsFromQueryParam[T any](items []T, param string, getKey func(item T) (int64, string)) (ret []int64) {
+	if param == "" {
+		return nil
+	}
+	m := makeItemIdNameMap(items, getKey)
+	for key := range strings.SplitSeq(param, ",") {
+		if item, ok := m[strings.ToLower(key)]; ok {
+			id, _ := getKey(item)
+			ret = append(ret, id)
+		}
+	}
+	return ret
+}
+
+func retrieveRepoIssueMetaDataWithPrefill(ctx *context.Context, repo *repo_model.Repository, isPull bool) *IssuePageMetaData {
+	data := retrieveRepoIssueMetaData(ctx, repo, nil, isPull)
+	if ctx.Written() {
+		return data
+	}
+
+	// label
+	paramLabel := ctx.FormString(newIssuePrefillLabel, ctx.FormString(newIssuePrefillLabelFallback))
+	labelIDs := pickItemIDsFromQueryParam(data.LabelsData.AllLabels, paramLabel, func(label *issues_model.Label) (int64, string) {
+		return label.ID, label.Name
+	})
+	data.LabelsData.SetSelectedLabelIDs(labelIDs)
+
+	// milestone
+	paramMilestone := ctx.FormString(newIssuePrefillMilestone)
+	allMilestones := slices.Concat(data.MilestonesData.OpenMilestones, data.MilestonesData.ClosedMilestones)
+	milestoneIDs := pickItemIDsFromQueryParam(allMilestones, paramMilestone, func(milestone *issues_model.Milestone) (int64, string) {
+		return milestone.ID, milestone.Name
+	})
+	if len(milestoneIDs) > 0 {
+		data.MilestonesData.SelectedMilestoneID = milestoneIDs[0]
+	}
+
+	// project
+	paramProject := ctx.FormString(newIssuePrefillProject)
+	allProjects := slices.Concat(data.ProjectsData.OpenProjects, data.ProjectsData.ClosedProjects)
+	projectOpenIDs := pickItemIDsFromQueryParam(allProjects, paramProject, func(project *project_model.Project) (int64, string) {
+		return project.ID, project.Title
+	})
+	data.SetSelectedProjectIDs(projectOpenIDs)
+
+	// assignee
+	paramAssignee := ctx.FormString(newIssuePrefillAssignee)
+	assigneeIDs := pickItemIDsFromQueryParam(data.AssigneesData.CandidateAssignees, paramAssignee, func(user *user_model.User) (int64, string) {
+		return user.ID, user.Name
+	})
+	data.AssigneesData.SelectedAssigneeIDs = base.JoinInt64s(assigneeIDs, ",")
+	return data
+}
+
 func (d *IssuePageMetaData) retrieveMilestonesDataForIssueWriter(ctx *context.Context) {
 	var err error
 	if d.Issue != nil {

routers/web/repo/issue_page_meta_test.go

@@ -0,0 +1,122 @@
+// Copyright 2026 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package repo
+
+import (
+	"net/url"
+	"slices"
+	"testing"
+
+	"gitea.dev/models/db"
+	issues_model "gitea.dev/models/issues"
+	"gitea.dev/models/perm"
+	access_model "gitea.dev/models/perm/access"
+	project_model "gitea.dev/models/project"
+	"gitea.dev/models/unittest"
+	user_model "gitea.dev/models/user"
+	"gitea.dev/modules/base"
+	"gitea.dev/services/contexttest"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestRetrieveRepoIssueMetaDataWithPrefill(t *testing.T) {
+	unittest.PrepareTestEnv(t)
+	require.NoError(t, db.Insert(t.Context(),
+		[]*issues_model.Label{
+			{ID: 100, RepoID: 1, Name: "Bug"},
+			{ID: 101, RepoID: 1, Name: "Feature Request"},
+			{ID: 102, RepoID: 2, Name: "Other Label"},
+		},
+		[]*issues_model.Milestone{
+			{ID: 100, RepoID: 1, Name: "Release One"},
+			{ID: 101, RepoID: 1, Name: "Release Two"},
+			{ID: 102, RepoID: 1, Name: "Closed Milestone", IsClosed: true},
+			{ID: 103, RepoID: 2, Name: "Other Milestone"},
+		},
+		[]*project_model.Project{
+			{ID: 100, RepoID: 1, Title: "Open Project", Type: project_model.TypeRepository},
+			{ID: 101, RepoID: 1, Title: "Closed Project", Type: project_model.TypeRepository, IsClosed: true},
+			{ID: 102, RepoID: 2, Title: "Other Project", Type: project_model.TypeRepository},
+		},
+		[]*user_model.User{
+			{ID: 100, Name: "Alice", LowerName: "alice", IsActive: true},
+			{ID: 101, Name: "Bob", LowerName: "bob", IsActive: true},
+			{ID: 102, Name: "OtherUser", LowerName: "otheruser", IsActive: true},
+		},
+		[]*access_model.Access{
+			{RepoID: 1, UserID: 100, Mode: perm.AccessModeWrite},
+			{RepoID: 1, UserID: 101, Mode: perm.AccessModeWrite},
+		},
+	))
+
+	type testCase struct {
+		name        string
+		query       url.Values
+		labelIDs    []int64
+		milestoneID int64
+		projectIDs  []int64
+		assigneeIDs []int64
+	}
+	for _, tc := range []testCase{
+		{
+			name: "empty",
+		},
+		{
+			name: "case-insensitive names",
+			query: url.Values{
+				"label":     {"bUG,fEATURE rEQUEST"},
+				"milestone": {"rELEASE oNE"},
+				"project":   {"cLOSED pROJECT,oPEN pROJECT"},
+				"assignee":  {"bOB,aLICE"},
+			},
+			labelIDs:    []int64{100, 101},
+			milestoneID: 100,
+			projectIDs:  []int64{101, 100},
+			assigneeIDs: []int64{101, 100},
+		},
+		{
+			name: "mixed IDs and names with invalid values",
+			query: url.Values{
+				"label":     {"missing,102,Other Label,101,Bug,100,999"},
+				"milestone": {"missing,102,Closed Milestone,103,Other Milestone,101,Release One,999"},
+				"project":   {"missing,102,Other Project,101,Open Project,999"},
+				"assignee":  {"missing,102,OtherUser,101,Alice,999"},
+			},
+			labelIDs:    []int64{100, 101},
+			milestoneID: 102,
+			projectIDs:  []int64{101, 100},
+			assigneeIDs: []int64{101, 100},
+		},
+		{
+			name:     "labels fallback",
+			query:    url.Values{"labels": {"101,Bug"}},
+			labelIDs: []int64{100, 101},
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			ctx, _ := contexttest.MockContext(t, "/dummy?"+tc.query.Encode())
+			contexttest.LoadUser(t, ctx, 2)
+			contexttest.LoadRepo(t, ctx, 1)
+
+			data := retrieveRepoIssueMetaDataWithPrefill(ctx, ctx.Repo.Repository, false)
+			require.False(t, ctx.Written())
+			assert.Same(t, data, ctx.Data["IssuePageMetaData"])
+			assert.True(t, data.CanModifyIssueOrPull)
+			assert.Equal(t, base.JoinInt64s(tc.labelIDs, ","), data.LabelsData.SelectedLabelIDs)
+			for _, label := range data.LabelsData.AllLabels {
+				assert.Equal(t, slices.Contains(tc.labelIDs, label.ID), label.IsChecked, label.Name)
+			}
+			assert.Equal(t, tc.milestoneID, data.MilestonesData.SelectedMilestoneID)
+			assert.Equal(t, tc.projectIDs, data.ProjectsData.SelectedProjectIDs)
+			var projectIDs []int64
+			for _, card := range data.ProjectsData.ProjectCards {
+				projectIDs = append(projectIDs, card.Project.ID)
+			}
+			assert.Equal(t, tc.projectIDs, projectIDs)
+			assert.Equal(t, base.JoinInt64s(tc.assigneeIDs, ","), data.AssigneesData.SelectedAssigneeIDs)
+		})
+	}
+}

routers/web/repo/pull.go

@@ -1326,7 +1326,7 @@ func CompareAndPullRequestPost(ctx *context.Context) {
 		ctx.JSONError(ctx.Tr("repo.pulls.no_common_history"))
 		return
 	}
-	validateRet := ValidateRepoMetasForNewIssue(ctx, *form, true)
+	validateRet := ValidateRepoMetasForCreateIssue(ctx, *form, true)
 	if ctx.Written() {
 		return
 	}

templates/repo/issue/choose.tmpl

@@ -15,7 +15,7 @@
 						<br>{{.About}}
 					</div>
 					<div class="column tw-text-right">
-						<a href="{{$.RepoLink}}/issues/new?template={{.FileName}}{{if $.milestone}}&milestone={{$.milestone}}{{end}}{{if $.project}}&project={{$.project}}{{end}}" class="ui primary button">{{ctx.Locale.Tr "repo.issues.choose.get_started"}}</a>
+						<a href="{{$.RepoLink}}/issues/new?template={{.FileName}}&{{$.PrefillQuery}}" class="ui primary button">{{ctx.Locale.Tr "repo.issues.choose.get_started"}}</a>
 					</div>
 				</div>
 			</div>
@@ -41,7 +41,7 @@
 						<br/>{{ctx.Locale.Tr "repo.issues.choose.blank_about"}}
 					</div>
 					<div class="column tw-text-right">
-						<a href="{{.RepoLink}}/issues/new?{{if .milestone}}&milestone={{.milestone}}{{end}}{{if $.project}}&project={{$.project}}{{end}}" class="ui primary button">{{ctx.Locale.Tr "repo.issues.choose.get_started"}}</a>
+						<a href="{{.RepoLink}}/issues/new?{{$.PrefillQuery}}" class="ui primary button">{{ctx.Locale.Tr "repo.issues.choose.get_started"}}</a>
 					</div>
 				</div>
 			</div>