Allow custom default merge message with .gitea/default_merge_message/<merge_style>_TEMPLATE.md (#18177)

* Allow custom default merge message with .gitea/MERGE_MESSAGE_<merge_style>_TEMPLATE.md

* Some improvements

* Follow some advices

* Fix bug

* Fix bug

* Fix lint

* Fix close comment

* Fix test

* Fix and docs

* Improve codes

* Update docs and remove unnecessary variables

* return error for GetDefaultMergeMessage

* Fix test

* improve code

* ignore unknow unit type

* return error for GetDefaultMergeMessage

* Update services/pull/merge.go

* Some improvements

* Follow some advices

* Fix bug

* Fix lint

* Improve codes

* Update docs and remove unnecessary variables

* return error for GetDefaultMergeMessage

* improve code

* Handle deleted HeadRepo in GetDefaultMergeMessage

Signed-off-by: Andrew Thornton <art27@cantab.net>

* Fix test

* Fix test

Co-authored-by: zeripath <art27@cantab.net>

docs/content/doc/usage/issue-pull-request-templates.en-us.md

@@ -43,6 +43,39 @@ Possible file names for PR templates:
 - `.github/PULL_REQUEST_TEMPLATE.md`
 - `.github/pull_request_template.md`
 
+Possible file names for PR default merge message templates:
+
+- `.gitea/default_merge_message/MERGE_TEMPLATE.md`
+- `.gitea/default_merge_message/REBASE_TEMPLATE.md`
+- `.gitea/default_merge_message/REBASE-MERGE_TEMPLATE.md`
+- `.gitea/default_merge_message/SQUASH_TEMPLATE.md`
+- `.gitea/default_merge_message/MANUALLY-MERGED_TEMPLATE.md`
+- `.gitea/default_merge_message/REBASE-UPDATE-ONLY_TEMPLATE.md`
+
+Possible file names for PR default merge message templates:
+
+- `.gitea/default_merge_message/MERGE_TEMPLATE.md`
+- `.gitea/default_merge_message/REBASE_TEMPLATE.md`
+- `.gitea/default_merge_message/REBASE-MERGE_TEMPLATE.md`
+- `.gitea/default_merge_message/SQUASH_TEMPLATE.md`
+- `.gitea/default_merge_message/MANUALLY-MERGED_TEMPLATE.md`
+- `.gitea/default_merge_message/REBASE-UPDATE-ONLY_TEMPLATE.md`
+
+You can use the following variables enclosed in `${}` inside these templates which follow [os.Expand](https://pkg.go.dev/os#Expand) syntax:
+
+- BaseRepoOwnerName: Base repository owner name of this pull request
+- BaseRepoName: Base repository name of this pull request
+- BaseBranch: Base repository target branch name of this pull request
+- HeadRepoOwnerName: Head repository owner name of this pull request
+- HeadRepoName: Head repository name of this pull request
+- HeadBranch: Head repository branch name of this pull request
+- PullRequestTitle: Pull request's title
+- PullRequestDescription: Pull request's description
+- PullRequestPosterName: Pull request's poster name
+- PullRequestIndex: Pull request's index number
+- PullRequestReference: Pull request's reference char with index number. i.e. #1, !2
+- ClosingIssues: return a string contains all issues which will be closed by this pull request i.e. `close #1, close #2`
+
 Additionally, the New Issue page URL can be suffixed with `?title=Issue+Title&body=Issue+Text` and the form will be populated with those strings. Those strings will be used instead of the template if there is one.
 
 ## Issue Template Directory

integrations/pull_merge_test.go

@@ -6,6 +6,7 @@ package integrations
 
 import (
 	"bytes"
+	"context"
 	"fmt"
 	"net/http"
 	"net/http/httptest"
@@ -243,11 +244,11 @@ func TestCantMergeConflict(t *testing.T) {
 		gitRepo, err := git.OpenRepository(git.DefaultContext, repo_model.RepoPath(user1.Name, repo1.Name))
 		assert.NoError(t, err)
 
-		err = pull.Merge(pr, user1, gitRepo, repo_model.MergeStyleMerge, "", "CONFLICT")
+		err = pull.Merge(context.Background(), pr, user1, gitRepo, repo_model.MergeStyleMerge, "", "CONFLICT")
 		assert.Error(t, err, "Merge should return an error due to conflict")
 		assert.True(t, models.IsErrMergeConflicts(err), "Merge error is not a conflict error")
 
-		err = pull.Merge(pr, user1, gitRepo, repo_model.MergeStyleRebase, "", "CONFLICT")
+		err = pull.Merge(context.Background(), pr, user1, gitRepo, repo_model.MergeStyleRebase, "", "CONFLICT")
 		assert.Error(t, err, "Merge should return an error due to conflict")
 		assert.True(t, models.IsErrRebaseConflicts(err), "Merge error is not a conflict error")
 		gitRepo.Close()
@@ -342,7 +343,7 @@ func TestCantMergeUnrelated(t *testing.T) {
 			BaseBranch: "base",
 		}).(*models.PullRequest)
 
-		err = pull.Merge(pr, user1, gitRepo, repo_model.MergeStyleMerge, "", "UNRELATED")
+		err = pull.Merge(context.Background(), pr, user1, gitRepo, repo_model.MergeStyleMerge, "", "UNRELATED")
 		assert.Error(t, err, "Merge should return an error due to unrelated")
 		assert.True(t, models.IsErrMergeUnrelatedHistories(err), "Merge error is not a unrelated histories error")
 		gitRepo.Close()

models/pull.go

@@ -13,7 +13,6 @@ import (
 
 	"code.gitea.io/gitea/models/db"
 	repo_model "code.gitea.io/gitea/models/repo"
-	"code.gitea.io/gitea/models/unit"
 	user_model "code.gitea.io/gitea/models/user"
 	"code.gitea.io/gitea/modules/git"
 	"code.gitea.io/gitea/modules/log"
@@ -228,34 +227,6 @@ func (pr *PullRequest) LoadProtectedBranchCtx(ctx context.Context) (err error) {
 	return
 }
 
-// GetDefaultMergeMessage returns default message used when merging pull request
-func (pr *PullRequest) GetDefaultMergeMessage(ctx context.Context) (string, error) {
-	if pr.HeadRepo == nil {
-		var err error
-		pr.HeadRepo, err = repo_model.GetRepositoryByIDCtx(ctx, pr.HeadRepoID)
-		if err != nil {
-			return "", fmt.Errorf("GetRepositoryById[%d]: %v", pr.HeadRepoID, err)
-		}
-	}
-	if err := pr.LoadIssueCtx(ctx); err != nil {
-		return "", fmt.Errorf("Cannot load issue %d for PR id %d: Error: %v", pr.IssueID, pr.ID, err)
-	}
-	if err := pr.LoadBaseRepoCtx(ctx); err != nil {
-		return "", fmt.Errorf("LoadBaseRepo: %v", err)
-	}
-
-	issueReference := "#"
-	if pr.BaseRepo.UnitEnabledCtx(ctx, unit.TypeExternalTracker) {
-		issueReference = "!"
-	}
-
-	if pr.BaseRepoID == pr.HeadRepoID {
-		return fmt.Sprintf("Merge pull request '%s' (%s%d) from %s into %s", pr.Issue.Title, issueReference, pr.Issue.Index, pr.HeadBranch, pr.BaseBranch), nil
-	}
-
-	return fmt.Sprintf("Merge pull request '%s' (%s%d) from %s:%s into %s", pr.Issue.Title, issueReference, pr.Issue.Index, pr.HeadRepo.FullName(), pr.HeadBranch, pr.BaseBranch), nil
-}
-
 // ReviewCount represents a count of Reviews
 type ReviewCount struct {
 	IssueID int64
@@ -338,20 +309,6 @@ func (pr *PullRequest) getReviewedByLines(writer io.Writer) error {
 	return committer.Commit()
 }
 
-// GetDefaultSquashMessage returns default message used when squash and merging pull request
-func (pr *PullRequest) GetDefaultSquashMessage(ctx context.Context) (string, error) {
-	if err := pr.LoadIssueCtx(ctx); err != nil {
-		return "", fmt.Errorf("LoadIssue: %v", err)
-	}
-	if err := pr.LoadBaseRepoCtx(ctx); err != nil {
-		return "", fmt.Errorf("LoadBaseRepo: %v", err)
-	}
-	if pr.BaseRepo.UnitEnabledCtx(ctx, unit.TypeExternalTracker) {
-		return fmt.Sprintf("%s (!%d)", pr.Issue.Title, pr.Issue.Index), nil
-	}
-	return fmt.Sprintf("%s (#%d)", pr.Issue.Title, pr.Issue.Index), nil
-}
-
 // GetGitRefName returns git ref for hidden pull request branch
 func (pr *PullRequest) GetGitRefName() string {
 	return fmt.Sprintf("%s%d/head", git.PullPrefix, pr.Index)

models/pull_test.go

@@ -8,10 +8,7 @@ import (
 	"testing"
 
 	"code.gitea.io/gitea/models/db"
-	repo_model "code.gitea.io/gitea/models/repo"
-	"code.gitea.io/gitea/models/unit"
 	"code.gitea.io/gitea/models/unittest"
-	user_model "code.gitea.io/gitea/models/user"
 
 	"github.com/stretchr/testify/assert"
 )
@@ -256,53 +253,3 @@ func TestPullRequest_GetWorkInProgressPrefixWorkInProgress(t *testing.T) {
 	pr.Issue.Title = "[wip] " + original
 	assert.Equal(t, "[wip]", pr.GetWorkInProgressPrefix())
 }
-
-func TestPullRequest_GetDefaultMergeMessage_InternalTracker(t *testing.T) {
-	assert.NoError(t, unittest.PrepareTestDatabase())
-	pr := unittest.AssertExistsAndLoadBean(t, &PullRequest{ID: 2}).(*PullRequest)
-
-	msg, err := pr.GetDefaultMergeMessage(db.DefaultContext)
-	assert.NoError(t, err)
-	assert.Equal(t, "Merge pull request 'issue3' (#3) from branch2 into master", msg)
-
-	pr.BaseRepoID = 1
-	pr.HeadRepoID = 2
-	msg, err = pr.GetDefaultMergeMessage(db.DefaultContext)
-	assert.NoError(t, err)
-	assert.Equal(t, "Merge pull request 'issue3' (#3) from user2/repo1:branch2 into master", msg)
-}
-
-func TestPullRequest_GetDefaultMergeMessage_ExternalTracker(t *testing.T) {
-	assert.NoError(t, unittest.PrepareTestDatabase())
-
-	externalTracker := repo_model.RepoUnit{
-		Type: unit.TypeExternalTracker,
-		Config: &repo_model.ExternalTrackerConfig{
-			ExternalTrackerFormat: "https://someurl.com/{user}/{repo}/{issue}",
-		},
-	}
-	baseRepo := &repo_model.Repository{Name: "testRepo", ID: 1}
-	baseRepo.Owner = &user_model.User{Name: "testOwner"}
-	baseRepo.Units = []*repo_model.RepoUnit{&externalTracker}
-
-	pr := unittest.AssertExistsAndLoadBean(t, &PullRequest{ID: 2, BaseRepo: baseRepo}).(*PullRequest)
-
-	msg, err := pr.GetDefaultMergeMessage(db.DefaultContext)
-	assert.NoError(t, err)
-	assert.Equal(t, "Merge pull request 'issue3' (!3) from branch2 into master", msg)
-
-	pr.BaseRepoID = 1
-	pr.HeadRepoID = 2
-	msg, err = pr.GetDefaultMergeMessage(db.DefaultContext)
-	assert.NoError(t, err)
-	assert.Equal(t, "Merge pull request 'issue3' (!3) from user2/repo1:branch2 into master", msg)
-}
-
-func TestPullRequest_GetDefaultSquashMessage(t *testing.T) {
-	assert.NoError(t, unittest.PrepareTestDatabase())
-	pr := unittest.AssertExistsAndLoadBean(t, &PullRequest{ID: 2}).(*PullRequest)
-
-	msg, err := pr.GetDefaultSquashMessage(db.DefaultContext)
-	assert.NoError(t, err)
-	assert.Equal(t, "issue3 (#3)", msg)
-}

models/repo/repo_unit.go

@@ -173,8 +173,6 @@ func (r *RepoUnit) BeforeSet(colName string, val xorm.Cell) {
 	switch colName {
 	case "type":
 		switch unit.Type(db.Cell2Int64(val)) {
-		case unit.TypeCode, unit.TypeReleases, unit.TypeWiki, unit.TypeProjects:
-			r.Config = new(UnitConfig)
 		case unit.TypeExternalWiki:
 			r.Config = new(ExternalWikiConfig)
 		case unit.TypeExternalTracker:
@@ -183,8 +181,10 @@ func (r *RepoUnit) BeforeSet(colName string, val xorm.Cell) {
 			r.Config = new(PullRequestsConfig)
 		case unit.TypeIssues:
 			r.Config = new(IssuesConfig)
+		case unit.TypeCode, unit.TypeReleases, unit.TypeWiki, unit.TypeProjects:
+			fallthrough
 		default:
-			panic(fmt.Sprintf("unrecognized repo unit type: %v", *val))
+			r.Config = new(UnitConfig)
 		}
 	}
 }

modules/git/commit.go

@@ -17,6 +17,7 @@ import (
 	"strings"
 
 	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/modules/util"
 )
 
 // Commit represents a git commit.
@@ -306,6 +307,35 @@ func (c *Commit) HasFile(filename string) (bool, error) {
 	return true, nil
 }
 
+// GetFileContent reads a file content as a string or returns false if this was not possible
+func (c *Commit) GetFileContent(filename string, limit int) (string, error) {
+	entry, err := c.GetTreeEntryByPath(filename)
+	if err != nil {
+		return "", err
+	}
+
+	r, err := entry.Blob().DataAsync()
+	if err != nil {
+		return "", err
+	}
+	defer r.Close()
+
+	if limit > 0 {
+		bs := make([]byte, limit)
+		n, err := util.ReadAtMost(r, bs)
+		if err != nil {
+			return "", err
+		}
+		return string(bs[:n]), nil
+	}
+
+	bytes, err := io.ReadAll(r)
+	if err != nil {
+		return "", err
+	}
+	return string(bytes), nil
+}
+
 // GetSubModules get all the sub modules of current revision git tree
 func (c *Commit) GetSubModules() (*ObjectCache, error) {
 	if c.submoduleCache != nil {

routers/api/v1/repo/pull.go

@@ -801,14 +801,26 @@ func MergePullRequest(ctx *context.APIContext) {
 		return
 	}
 
-	// set defaults to propagate needed fields
+	if len(form.Do) == 0 {
-	if err := form.SetDefaults(ctx, pr); err != nil {
+		form.Do = string(repo_model.MergeStyleMerge)
-		ctx.ServerError("SetDefaults", fmt.Errorf("SetDefaults: %v", err))
+	}
+
+	message := strings.TrimSpace(form.MergeTitleField)
+	if len(message) == 0 {
+		message, err = pull_service.GetDefaultMergeMessage(ctx.Repo.GitRepo, pr, repo_model.MergeStyle(form.Do))
+		if err != nil {
+			ctx.Error(http.StatusInternalServerError, "GetDefaultMergeMessage", err)
 			return
 		}
+	}
+
+	form.MergeMessageField = strings.TrimSpace(form.MergeMessageField)
+	if len(form.MergeMessageField) > 0 {
+		message += "\n\n" + form.MergeMessageField
+	}
 
 	if form.MergeWhenChecksSucceed {
-		scheduled, err := automerge.ScheduleAutoMerge(ctx, ctx.Doer, pr, repo_model.MergeStyle(form.Do), form.MergeTitleField)
+		scheduled, err := automerge.ScheduleAutoMerge(ctx, ctx.Doer, pr, repo_model.MergeStyle(form.Do), message)
 		if err != nil {
 			if pull_model.IsErrAlreadyScheduledToAutoMerge(err) {
 				ctx.Error(http.StatusConflict, "ScheduleAutoMerge", err)
@@ -823,7 +835,7 @@ func MergePullRequest(ctx *context.APIContext) {
 		}
 	}
 
-	if err := pull_service.Merge(pr, ctx.Doer, ctx.Repo.GitRepo, repo_model.MergeStyle(form.Do), form.HeadCommitID, form.MergeTitleField); err != nil {
+	if err := pull_service.Merge(ctx, pr, ctx.Doer, ctx.Repo.GitRepo, repo_model.MergeStyle(form.Do), form.HeadCommitID, message); err != nil {
 		if models.IsErrInvalidMergeStyle(err) {
 			ctx.Error(http.StatusMethodNotAllowed, "Invalid merge style", fmt.Errorf("%s is not allowed an allowed merge style for this repository", repo_model.MergeStyle(form.Do)))
 		} else if models.IsErrMergeConflicts(err) {

routers/web/repo/issue.go

@@ -712,8 +712,6 @@ func RetrieveRepoMetas(ctx *context.Context, repo *repo_model.Repository, isPull
 }
 
 func getFileContentFromDefaultBranch(ctx *context.Context, filename string) (string, bool) {
-	var bytes []byte
-
 	if ctx.Repo.Commit == nil {
 		var err error
 		ctx.Repo.Commit, err = ctx.Repo.GitRepo.GetBranchCommit(ctx.Repo.Repository.DefaultBranch)
@@ -734,7 +732,7 @@ func getFileContentFromDefaultBranch(ctx *context.Context, filename string) (str
 		return "", false
 	}
 	defer r.Close()
-	bytes, err = io.ReadAll(r)
+	bytes, err := io.ReadAll(r)
 	if err != nil {
 		return "", false
 	}
@@ -1574,26 +1572,42 @@ func ViewIssue(ctx *context.Context) {
 		}
 		prConfig := prUnit.PullRequestsConfig()
 
+		var mergeStyle repo_model.MergeStyle
 		// Check correct values and select default
 		if ms, ok := ctx.Data["MergeStyle"].(repo_model.MergeStyle); !ok ||
 			!prConfig.IsMergeStyleAllowed(ms) {
 			defaultMergeStyle := prConfig.GetDefaultMergeStyle()
 			if prConfig.IsMergeStyleAllowed(defaultMergeStyle) && !ok {
-				ctx.Data["MergeStyle"] = defaultMergeStyle
+				mergeStyle = defaultMergeStyle
 			} else if prConfig.AllowMerge {
-				ctx.Data["MergeStyle"] = repo_model.MergeStyleMerge
+				mergeStyle = repo_model.MergeStyleMerge
 			} else if prConfig.AllowRebase {
-				ctx.Data["MergeStyle"] = repo_model.MergeStyleRebase
+				mergeStyle = repo_model.MergeStyleRebase
 			} else if prConfig.AllowRebaseMerge {
-				ctx.Data["MergeStyle"] = repo_model.MergeStyleRebaseMerge
+				mergeStyle = repo_model.MergeStyleRebaseMerge
 			} else if prConfig.AllowSquash {
-				ctx.Data["MergeStyle"] = repo_model.MergeStyleSquash
+				mergeStyle = repo_model.MergeStyleSquash
 			} else if prConfig.AllowManualMerge {
-				ctx.Data["MergeStyle"] = repo_model.MergeStyleManuallyMerged
+				mergeStyle = repo_model.MergeStyleManuallyMerged
-			} else {
+			}
-				ctx.Data["MergeStyle"] = ""
+		}
+
+		ctx.Data["MergeStyle"] = mergeStyle
+
+		defaultMergeMessage, err := pull_service.GetDefaultMergeMessage(ctx.Repo.GitRepo, pull, mergeStyle)
+		if err != nil {
+			ctx.ServerError("GetDefaultMergeMessage", err)
+			return
 		}
+		ctx.Data["DefaultMergeMessage"] = defaultMergeMessage
+
+		defaultSquashMergeMessage, err := pull_service.GetDefaultMergeMessage(ctx.Repo.GitRepo, pull, repo_model.MergeStyleSquash)
+		if err != nil {
+			ctx.ServerError("GetDefaultSquashMergeMessage", err)
+			return
 		}
+		ctx.Data["DefaultSquashMergeMessage"] = defaultSquashMergeMessage
+
 		if err = pull.LoadProtectedBranch(); err != nil {
 			ctx.ServerError("LoadProtectedBranch", err)
 			return

routers/web/repo/pull.go

@@ -950,13 +950,22 @@ func MergePullRequest(ctx *context.Context) {
 		return
 	}
 
-	// set defaults to propagate needed fields
+	message := strings.TrimSpace(form.MergeTitleField)
-	if err := form.SetDefaults(ctx, pr); err != nil {
+	if len(message) == 0 {
-		ctx.ServerError("SetDefaults", fmt.Errorf("SetDefaults: %v", err))
+		var err error
+		message, err = pull_service.GetDefaultMergeMessage(ctx.Repo.GitRepo, pr, repo_model.MergeStyle(form.Do))
+		if err != nil {
+			ctx.ServerError("GetDefaultMergeMessage", err)
 			return
 		}
+	}
+
+	form.MergeMessageField = strings.TrimSpace(form.MergeMessageField)
+	if len(form.MergeMessageField) > 0 {
+		message += "\n\n" + form.MergeMessageField
+	}
 
-	if err := pull_service.Merge(pr, ctx.Doer, ctx.Repo.GitRepo, repo_model.MergeStyle(form.Do), form.HeadCommitID, form.MergeTitleField); err != nil {
+	if err := pull_service.Merge(ctx, pr, ctx.Doer, ctx.Repo.GitRepo, repo_model.MergeStyle(form.Do), form.HeadCommitID, message); err != nil {
 		if models.IsErrInvalidMergeStyle(err) {
 			ctx.Flash.Error(ctx.Tr("repo.pulls.invalid_merge_option"))
 			ctx.Redirect(issue.Link())

services/automerge/automerge.go

@@ -234,7 +234,7 @@ func handlePull(pullID int64, sha string) {
 		defer baseGitRepo.Close()
 	}
 
-	if err := pull_service.Merge(pr, doer, baseGitRepo, scheduledPRM.MergeStyle, "", scheduledPRM.Message); err != nil {
+	if err := pull_service.Merge(ctx, pr, doer, baseGitRepo, scheduledPRM.MergeStyle, "", scheduledPRM.Message); err != nil {
 		log.Error("pull_service.Merge: %v", err)
 		return
 	}

services/forms/repo_form.go

@@ -6,7 +6,6 @@
 package forms
 
 import (
-	stdContext "context"
 	"net/http"
 	"net/url"
 	"strings"
@@ -602,31 +601,6 @@ func (f *MergePullRequestForm) Validate(req *http.Request, errs binding.Errors)
 	return middleware.Validate(errs, ctx.Data, f, ctx.Locale)
 }
 
-// SetDefaults if not provided for mergestyle and commit message
-func (f *MergePullRequestForm) SetDefaults(ctx stdContext.Context, pr *models.PullRequest) (err error) {
-	if f.Do == "" {
-		f.Do = "merge"
-	}
-
-	f.MergeTitleField = strings.TrimSpace(f.MergeTitleField)
-	if len(f.MergeTitleField) == 0 {
-		switch f.Do {
-		case "merge", "rebase-merge":
-			f.MergeTitleField, err = pr.GetDefaultMergeMessage(ctx)
-		case "squash":
-			f.MergeTitleField, err = pr.GetDefaultSquashMessage(ctx)
-		}
-	}
-
-	f.MergeMessageField = strings.TrimSpace(f.MergeMessageField)
-	if len(f.MergeMessageField) > 0 {
-		f.MergeTitleField += "\n\n" + f.MergeMessageField
-		f.MergeMessageField = ""
-	}
-
-	return
-}
-
 // CodeCommentForm form for adding code comments for PRs
 type CodeCommentForm struct {
 	Origin         string `binding:"Required;In(timeline,diff)"`

services/pull/merge.go

@@ -13,6 +13,7 @@ import (
 	"os"
 	"path/filepath"
 	"regexp"
+	"strconv"
 	"strings"
 	"time"
 
@@ -33,9 +34,101 @@ import (
 	issue_service "code.gitea.io/gitea/services/issue"
 )
 
+// GetDefaultMergeMessage returns default message used when merging pull request
+func GetDefaultMergeMessage(baseGitRepo *git.Repository, pr *models.PullRequest, mergeStyle repo_model.MergeStyle) (string, error) {
+	if err := pr.LoadHeadRepo(); err != nil {
+		return "", err
+	}
+	if err := pr.LoadBaseRepo(); err != nil {
+		return "", err
+	}
+	if pr.BaseRepo == nil {
+		return "", repo_model.ErrRepoNotExist{ID: pr.BaseRepoID}
+	}
+
+	if err := pr.LoadIssue(); err != nil {
+		return "", err
+	}
+
+	isExternalTracker := pr.BaseRepo.UnitEnabled(unit.TypeExternalTracker)
+	issueReference := "#"
+	if isExternalTracker {
+		issueReference = "!"
+	}
+
+	if mergeStyle != "" {
+		templateFilepath := fmt.Sprintf(".gitea/default_merge_message/%s_TEMPLATE.md", strings.ToUpper(string(mergeStyle)))
+		commit, err := baseGitRepo.GetBranchCommit(pr.BaseRepo.DefaultBranch)
+		if err != nil {
+			return "", err
+		}
+		templateContent, err := commit.GetFileContent(templateFilepath, setting.Repository.PullRequest.DefaultMergeMessageSize)
+		if err != nil {
+			if !git.IsErrNotExist(err) {
+				return "", err
+			}
+		} else {
+			vars := map[string]string{
+				"BaseRepoOwnerName":      pr.BaseRepo.OwnerName,
+				"BaseRepoName":           pr.BaseRepo.Name,
+				"BaseBranch":             pr.BaseBranch,
+				"HeadRepoOwnerName":      "",
+				"HeadRepoName":           "",
+				"HeadBranch":             pr.HeadBranch,
+				"PullRequestTitle":       pr.Issue.Title,
+				"PullRequestDescription": pr.Issue.Content,
+				"PullRequestPosterName":  pr.Issue.Poster.Name,
+				"PullRequestIndex":       strconv.FormatInt(pr.Index, 10),
+				"PullRequestReference":   fmt.Sprintf("%s%d", issueReference, pr.Index),
+			}
+			if pr.HeadRepo != nil {
+				vars["HeadRepoOwnerName"] = pr.HeadRepo.OwnerName
+				vars["HeadRepoName"] = pr.HeadRepo.Name
+			}
+			refs, err := pr.ResolveCrossReferences(baseGitRepo.Ctx)
+			if err == nil {
+				closeIssueIndexes := make([]string, 0, len(refs))
+				closeWord := "close"
+				if len(setting.Repository.PullRequest.CloseKeywords) > 0 {
+					closeWord = setting.Repository.PullRequest.CloseKeywords[0]
+				}
+				for _, ref := range refs {
+					if ref.RefAction == references.XRefActionCloses {
+						closeIssueIndexes = append(closeIssueIndexes, fmt.Sprintf("%s %s%d", closeWord, issueReference, ref.Issue.Index))
+					}
+				}
+				if len(closeIssueIndexes) > 0 {
+					vars["ClosingIssues"] = strings.Join(closeIssueIndexes, ", ")
+				} else {
+					vars["ClosingIssues"] = ""
+				}
+			}
+
+			return os.Expand(templateContent, func(s string) string {
+				return vars[s]
+			}), nil
+		}
+	}
+
+	// Squash merge has a different from other styles.
+	if mergeStyle == repo_model.MergeStyleSquash {
+		return fmt.Sprintf("%s (%s%d)", pr.Issue.Title, issueReference, pr.Issue.Index), nil
+	}
+
+	if pr.BaseRepoID == pr.HeadRepoID {
+		return fmt.Sprintf("Merge pull request '%s' (%s%d) from %s into %s", pr.Issue.Title, issueReference, pr.Issue.Index, pr.HeadBranch, pr.BaseBranch), nil
+	}
+
+	if pr.HeadRepo == nil {
+		return fmt.Sprintf("Merge pull request '%s' (%s%d) from <deleted>:%s into %s", pr.Issue.Title, issueReference, pr.Issue.Index, pr.HeadBranch, pr.BaseBranch), nil
+	}
+
+	return fmt.Sprintf("Merge pull request '%s' (%s%d) from %s:%s into %s", pr.Issue.Title, issueReference, pr.Issue.Index, pr.HeadRepo.FullName(), pr.HeadBranch, pr.BaseBranch), nil
+}
+
 // Merge merges pull request to base repository.
 // Caller should check PR is ready to be merged (review and status checks)
-func Merge(pr *models.PullRequest, doer *user_model.User, baseGitRepo *git.Repository, mergeStyle repo_model.MergeStyle, expectedHeadCommitID, message string) error {
+func Merge(ctx context.Context, pr *models.PullRequest, doer *user_model.User, baseGitRepo *git.Repository, mergeStyle repo_model.MergeStyle, expectedHeadCommitID, message string) error {
 	if err := pr.LoadHeadRepo(); err != nil {
 		log.Error("LoadHeadRepo: %v", err)
 		return fmt.Errorf("LoadHeadRepo: %v", err)
@@ -79,18 +172,18 @@ func Merge(pr *models.PullRequest, doer *user_model.User, baseGitRepo *git.Repos
 	pr.Merger = doer
 	pr.MergerID = doer.ID
 
-	if _, err := pr.SetMerged(db.DefaultContext); err != nil {
+	if _, err := pr.SetMerged(ctx); err != nil {
 		log.Error("setMerged [%d]: %v", pr.ID, err)
 	}
 
-	if err := pr.LoadIssueCtx(db.DefaultContext); err != nil {
+	if err := pr.LoadIssueCtx(ctx); err != nil {
 		log.Error("loadIssue [%d]: %v", pr.ID, err)
 	}
 
-	if err := pr.Issue.LoadRepo(db.DefaultContext); err != nil {
+	if err := pr.Issue.LoadRepo(ctx); err != nil {
 		log.Error("loadRepo for issue [%d]: %v", pr.ID, err)
 	}
-	if err := pr.Issue.Repo.GetOwner(db.DefaultContext); err != nil {
+	if err := pr.Issue.Repo.GetOwner(ctx); err != nil {
 		log.Error("GetOwner for issue repo [%d]: %v", pr.ID, err)
 	}
 
@@ -100,17 +193,17 @@ func Merge(pr *models.PullRequest, doer *user_model.User, baseGitRepo *git.Repos
 	cache.Remove(pr.Issue.Repo.GetCommitsCountCacheKey(pr.BaseBranch, true))
 
 	// Resolve cross references
-	refs, err := pr.ResolveCrossReferences(db.DefaultContext)
+	refs, err := pr.ResolveCrossReferences(ctx)
 	if err != nil {
 		log.Error("ResolveCrossReferences: %v", err)
 		return nil
 	}
 
 	for _, ref := range refs {
-		if err = ref.LoadIssueCtx(db.DefaultContext); err != nil {
+		if err = ref.LoadIssueCtx(ctx); err != nil {
 			return err
 		}
-		if err = ref.Issue.LoadRepo(db.DefaultContext); err != nil {
+		if err = ref.Issue.LoadRepo(ctx); err != nil {
 			return err
 		}
 		close := ref.RefAction == references.XRefActionCloses

services/pull/pull_test.go

@@ -8,6 +8,12 @@ package pull
 import (
 	"testing"
 
+	"code.gitea.io/gitea/models"
+	repo_model "code.gitea.io/gitea/models/repo"
+	"code.gitea.io/gitea/models/unit"
+	"code.gitea.io/gitea/models/unittest"
+	"code.gitea.io/gitea/modules/git"
+
 	"github.com/stretchr/testify/assert"
 )
 
@@ -29,3 +35,57 @@ func TestPullRequest_CommitMessageTrailersPattern(t *testing.T) {
 	assert.True(t, commitMessageTrailersPattern.MatchString("Additional whitespace is accepted.\n\nSigned-off-by \t :  \tBob   <bob@example.com>   "))
 	assert.True(t, commitMessageTrailersPattern.MatchString("Folded value.\n\nFolded-trailer: This is\n a folded\n   trailer value\nOther-Trailer: Value"))
 }
+
+func TestPullRequest_GetDefaultMergeMessage_InternalTracker(t *testing.T) {
+	assert.NoError(t, unittest.PrepareTestDatabase())
+	pr := unittest.AssertExistsAndLoadBean(t, &models.PullRequest{ID: 2}).(*models.PullRequest)
+
+	assert.NoError(t, pr.LoadBaseRepo())
+	gitRepo, err := git.OpenRepository(git.DefaultContext, pr.BaseRepo.RepoPath())
+	assert.NoError(t, err)
+	defer gitRepo.Close()
+
+	mergeMessage, err := GetDefaultMergeMessage(gitRepo, pr, "")
+	assert.NoError(t, err)
+	assert.Equal(t, "Merge pull request 'issue3' (#3) from branch2 into master", mergeMessage)
+
+	pr.BaseRepoID = 1
+	pr.HeadRepoID = 2
+	mergeMessage, err = GetDefaultMergeMessage(gitRepo, pr, "")
+	assert.NoError(t, err)
+	assert.Equal(t, "Merge pull request 'issue3' (#3) from user2/repo1:branch2 into master", mergeMessage)
+}
+
+func TestPullRequest_GetDefaultMergeMessage_ExternalTracker(t *testing.T) {
+	assert.NoError(t, unittest.PrepareTestDatabase())
+
+	externalTracker := repo_model.RepoUnit{
+		Type: unit.TypeExternalTracker,
+		Config: &repo_model.ExternalTrackerConfig{
+			ExternalTrackerFormat: "https://someurl.com/{user}/{repo}/{issue}",
+		},
+	}
+	baseRepo := unittest.AssertExistsAndLoadBean(t, &repo_model.Repository{ID: 1}).(*repo_model.Repository)
+	baseRepo.Units = []*repo_model.RepoUnit{&externalTracker}
+
+	pr := unittest.AssertExistsAndLoadBean(t, &models.PullRequest{ID: 2, BaseRepo: baseRepo}).(*models.PullRequest)
+
+	assert.NoError(t, pr.LoadBaseRepo())
+	gitRepo, err := git.OpenRepository(git.DefaultContext, pr.BaseRepo.RepoPath())
+	assert.NoError(t, err)
+	defer gitRepo.Close()
+
+	mergeMessage, err := GetDefaultMergeMessage(gitRepo, pr, "")
+	assert.NoError(t, err)
+
+	assert.Equal(t, "Merge pull request 'issue3' (!3) from branch2 into master", mergeMessage)
+
+	pr.BaseRepoID = 1
+	pr.HeadRepoID = 2
+	pr.BaseRepo = nil
+	pr.HeadRepo = nil
+	mergeMessage, err = GetDefaultMergeMessage(gitRepo, pr, "")
+	assert.NoError(t, err)
+
+	assert.Equal(t, "Merge pull request 'issue3' (#3) from user2/repo2:branch2 into master", mergeMessage)
+}

templates/repo/issue/view_content/pull.tmpl

@@ -329,7 +329,7 @@
 									{{.CsrfTokenHtml}}
 									<input type="hidden" name="head_commit_id" value="{{.PullHeadCommitID}}">
 									<div class="field">
-										<input type="text" name="merge_title_field" value="{{.Issue.PullRequest.GetDefaultMergeMessage $.Context}}">
+										<input type="text" name="merge_title_field" value="{{.DefaultMergeMessage}}">
 									</div>
 									<div class="field">
 										<textarea name="merge_message_field" rows="5" placeholder="{{$.i18n.Tr "repo.editor.commit_message_desc"}}">Reviewed-on: {{$.Issue.HTMLURL}}&#13;&#10;{{$approvers}}</textarea>
@@ -375,10 +375,7 @@
 									{{.CsrfTokenHtml}}
 									<input type="hidden" name="head_commit_id" value="{{.PullHeadCommitID}}">
 									<div class="field">
-										<input type="text" name="merge_title_field" value="{{.Issue.PullRequest.GetDefaultMergeMessage $.Context}}">
+										<input type="text" name="merge_title_field" value="{{.DefaultMergeMessage}}">
-									</div>
-									<div class="field">
-										<textarea name="merge_message_field" rows="5" placeholder="{{$.i18n.Tr "repo.editor.commit_message_desc"}}">Reviewed-on: {{$.Issue.HTMLURL}}&#13;&#10;{{$approvers}}</textarea>
 									</div>
 									<button class="ui green button" type="submit" name="do" value="rebase-merge">
 										{{$.i18n.Tr "repo.pulls.rebase_merge_commit_pull_request"}}
@@ -401,7 +398,7 @@
 									{{.CsrfTokenHtml}}
 									<input type="hidden" name="head_commit_id" value="{{.PullHeadCommitID}}">
 									<div class="field">
-										<input type="text" name="merge_title_field" value="{{.Issue.PullRequest.GetDefaultSquashMessage $.Context}}">
+										<input type="text" name="merge_title_field" value="{{.DefaultSquashMergeMessage}}">
 									</div>
 									<div class="field">
 										<textarea name="merge_message_field" rows="5" placeholder="{{$.i18n.Tr "repo.editor.commit_message_desc"}}">{{.GetCommitMessages}}Reviewed-on: {{$.Issue.HTMLURL}}&#13;&#10;{{$approvers}}</textarea>