Set the default branch for repositories generated from templates (#19136)

* Set the default branch for repositories generated from templates
* Allows default branch to be set through the API for repos generated from templates
* Update swagger API template
* Only set default branch to the one from the template if not specified
* Use specified default branch if it exists while generating git commits

Fix #19082 

Co-authored-by: John Olheiser <john.olheiser@gmail.com>
Co-authored-by: zeripath <art27@cantab.net>

models/repo_generate.go

@@ -21,6 +21,7 @@ import (
 // GenerateRepoOptions contains the template units to generate
 type GenerateRepoOptions struct {
 	Name          string
+	DefaultBranch string
 	Description   string
 	Private       bool
 	GitContent    bool

modules/repository/generate.go

@@ -184,7 +184,13 @@ func generateRepoCommit(ctx context.Context, repo, templateRepo, generateRepo *r
 		return fmt.Errorf("git remote add: %v", err)
 	}
 
-	return initRepoCommit(ctx, tmpDir, repo, repo.Owner, templateRepo.DefaultBranch)
+	// set default branch based on whether it's specified in the newly generated repo or not
+	defaultBranch := repo.DefaultBranch
+	if strings.TrimSpace(defaultBranch) == "" {
+		defaultBranch = templateRepo.DefaultBranch
+	}
+
+	return initRepoCommit(ctx, tmpDir, repo, repo.Owner, defaultBranch)
 }
 
 func generateGitContent(ctx context.Context, repo, templateRepo, generateRepo *repo_model.Repository) (err error) {
@@ -208,7 +214,11 @@ func generateGitContent(ctx context.Context, repo, templateRepo, generateRepo *r
 		return fmt.Errorf("getRepositoryByID: %v", err)
 	}
 
+	// if there was no default branch supplied when generating the repo, use the default one from the template
+	if strings.TrimSpace(repo.DefaultBranch) == "" {
 		repo.DefaultBranch = templateRepo.DefaultBranch
+	}
+
 	gitRepo, err := git.OpenRepositoryCtx(ctx, repo.RepoPath())
 	if err != nil {
 		return fmt.Errorf("openRepository: %v", err)
@@ -249,6 +259,7 @@ func GenerateRepository(ctx context.Context, doer, owner *user_model.User, templ
 		Name:          opts.Name,
 		LowerName:     strings.ToLower(opts.Name),
 		Description:   opts.Description,
+		DefaultBranch: opts.DefaultBranch,
 		IsPrivate:     opts.Private,
 		IsEmpty:       !opts.GitContent || templateRepo.IsEmpty,
 		IsFsckEnabled: templateRepo.IsFsckEnabled,

modules/structs/repo.go

@@ -201,6 +201,8 @@ type GenerateRepoOption struct {
 	// required: true
 	// unique: true
 	Name string `json:"name" binding:"Required;AlphaDashDot;MaxSize(100)"`
+	// Default branch of the new repository
+	DefaultBranch string `json:"default_branch"`
 	// Description of the repository to create
 	Description string `json:"description" binding:"MaxSize(255)"`
 	// Whether the repository is private

routers/api/v1/repo/repo.go

@@ -360,6 +360,7 @@ func Generate(ctx *context.APIContext) {
 
 	opts := models.GenerateRepoOptions{
 		Name:          form.Name,
+		DefaultBranch: form.DefaultBranch,
 		Description:   form.Description,
 		Private:       form.Private,
 		GitContent:    form.GitContent,

templates/swagger/v1_json.tmpl

@@ -15412,6 +15412,11 @@
           "type": "boolean",
           "x-go-name": "Avatar"
         },
+        "default_branch": {
+          "description": "Default branch of the new repository",
+          "type": "string",
+          "x-go-name": "DefaultBranch"
+        },
         "description": {
           "description": "Description of the repository to create",
           "type": "string",