Check existence of release before creating it

commands/release.go

@@ -84,36 +84,41 @@ func createRelease(cmd *Command, args *Args) {
 
 	tag := args.LastParam()
 	runInLocalRepo(func(localRepo *github.GitHubRepo, project *github.Project, client *github.Client) {
-		currentBranch, err := localRepo.CurrentBranch()
+		release, err := client.Release(project, tag)
 		utils.Check(err)
-		branchName := currentBranch.ShortName()
 
-		title, body, err := getTitleAndBodyFromFlags(flagReleaseMessage, flagReleaseFile)
-		utils.Check(err)
-
-		var editor *github.Editor
-		if title == "" {
-			message := releaseMessage(tag, project.Name, branchName)
-			editor, err = github.NewEditor("RELEASE", "release", message)
+		if release == nil {
+			currentBranch, err := localRepo.CurrentBranch()
 			utils.Check(err)
+			branchName := currentBranch.ShortName()
 
-			title, body, err = editor.EditTitleAndBody()
+			title, body, err := getTitleAndBodyFromFlags(flagReleaseMessage, flagReleaseFile)
 			utils.Check(err)
-		}
 
-		params := octokit.ReleaseParams{
-			TagName:         tag,
-			TargetCommitish: branchName,
-			Name:            title,
-			Body:            body,
-			Draft:           flagReleaseDraft,
-			Prerelease:      flagReleasePrerelease,
-		}
-		release, err := client.CreateRelease(project, params)
-		utils.Check(err)
+			var editor *github.Editor
+			if title == "" {
+				message := releaseMessage(tag, project.Name, branchName)
+				editor, err = github.NewEditor("RELEASE", "release", message)
+				utils.Check(err)
 
-		if editor != nil {
-			defer editor.DeleteFile()
+				title, body, err = editor.EditTitleAndBody()
+				utils.Check(err)
+			}
+
+			params := octokit.ReleaseParams{
+				TagName:         tag,
+				TargetCommitish: branchName,
+				Name:            title,
+				Body:            body,
+				Draft:           flagReleaseDraft,
+				Prerelease:      flagReleasePrerelease,
+			}
+			release, err = client.CreateRelease(project, params)
+			utils.Check(err)
+
+			if editor != nil {
+				defer editor.DeleteFile()
+			}
 		}
 
 		if flagReleaseAssets != "" {

github/client.go

@@ -266,6 +266,33 @@ func (client *Client) Releases(project *Project) (releases []octokit.Release, er
 	return
 }
 
+func (client *Client) Release(project *Project, tagName string) (release *octokit.Release, err error) {
+	url, err := octokit.ReleasesURL.Expand(octokit.M{"owner": project.Owner, "repo": project.Name})
+	if err != nil {
+		return
+	}
+
+	api, err := client.api()
+	if err != nil {
+		err = FormatError("getting release", err)
+		return
+	}
+
+	releases, result := api.Releases(client.requestURL(url)).All()
+	if result.HasError() {
+		err = FormatError("creating release", result.Err)
+		return
+	}
+
+	for _, release := range releases {
+		if release.TagName == tagName {
+			return &release, nil
+		}
+	}
+
+	return
+}
+
 func (client *Client) CreateRelease(project *Project, params octokit.ReleaseParams) (release *octokit.Release, err error) {
 	url, err := octokit.ReleasesURL.Expand(octokit.M{"owner": project.Owner, "repo": project.Name})
 	if err != nil {