Add branch name max length option to GitHub backend (closes #526)

Author: Benaiah

src/backends/git-gateway/implementation.js

@@ -70,6 +70,8 @@ export default class GitGateway extends GitHubBackend {
           branch: this.branch,
           tokenPromise: this.tokenPromise,
           commitAuthor: pick(userData, ["name", "email"]),
+          // this.config is set by the GitHubBackend constructor
+          branchNameMaxLength: this.config.getIn(["backend", "branch_name_max_length"]),
         });
         return userData;
       } else {

src/backends/github/API.js

@@ -15,6 +15,7 @@ export default class API {
     this.branch = config.branch || "master";
     this.repo = config.repo || "";
     this.repoURL = `/repos/${ this.repo }`;
+    this.branchNameMaxLength = config.branchNameMaxLength || 40;
   }
 
   user() {
@@ -85,8 +86,14 @@ export default class API {
     });
   }
 
+  truncateSlugForBranchName(slug) {
+    const slugMaxLength = this.branchNameMaxLength - CMS_BRANCH_PREFIX.length;
+    return slug.substring(0, slugMaxLength);
+  }
+
   generateBranchName(basename) {
-    return `${CMS_BRANCH_PREFIX}${basename}`;
+    const truncatedBasename = this.truncateSlugForBranchName(basename);
+    return `${ CMS_BRANCH_PREFIX }${ truncatedBasename }`;
   }
 
   checkMetadataRef() {
@@ -111,7 +118,10 @@ export default class API {
     });
   }
 
-  storeMetadata(key, data) {
+  storeMetadata(contentKey, data) {
+    // metadata filenames need to match branch names - see
+    // unpublishedEntries in src/backends/github/implementation.js
+    const key = this.truncateSlugForBranchName(contentKey);
     return this.checkMetadataRef()
     .then((branchData) => {
       const fileTree = {
@@ -135,7 +145,10 @@ export default class API {
     });
   }
 
-  retrieveMetadata(key) {
+  retrieveMetadata(contentKey) {
+    // metadata filenames need to match branch names - see
+    // unpublishedEntries in src/backends/github/implementation.js
+    const key = this.truncateSlugForBranchName(contentKey);
     const cache = LocalForage.getItem(`gh.meta.${ key }`);
     return cache.then((cached) => {
       if (cached && cached.expires > Date.now()) { return cached.data; }

src/backends/github/implementation.js

@@ -30,7 +30,13 @@ export default class GitHub {
 
   authenticate(state) {
     this.token = state.token;
-    this.api = new API({ token: this.token, branch: this.branch, repo: this.repo, api_root: this.api_root });
+    this.api = new API({
+      token: this.token,
+      branch: this.branch,
+      repo: this.repo,
+      api_root: this.api_root,
+      branchNameMaxLength: this.config.getIn(["backend", "branch_name_max_length"]),
+    });
     return this.api.user().then(user =>
       this.api.hasWriteAccess().then((isCollab) => {
         // Unauthorized user