make labpath opt-in

- old filepath urls still open classic UI
- form produces new `?labpath=` arg when a file path is chosen

lab is still 'default', but choice is frozen at link-creation time instead of at visit-time

Author: minrk

binderhub/main.py

@@ -70,11 +70,14 @@ async def get(self, provider_prefix, _unescaped_spec):
             nbviewer_url = 'https://nbviewer.jupyter.org/github'
             org, repo_name, ref = spec.split('/', 2)
             # NOTE: tornado unquotes query arguments too -> notebooks%2Findex.ipynb becomes notebooks/index.ipynb
-            filepath = self.get_argument('filepath', '').lstrip('/')
+            filepath = self.get_argument("labpath", "").lstrip("/")
+            if not filepath:
+                filepath = self.get_argument('filepath', '').lstrip('/')
+
 
             # Check if we have a JupyterLab + file path, if so then use it for the filepath
             urlpath = self.get_argument('urlpath', '').lstrip('/')
-            if urlpath.startswith("lab") and "/tree/" in urlpath:
+            if urlpath and "/tree/" in urlpath:
                 filepath = urlpath.split('tree/', 1)[-1]
 
             blob_or_tree = 'blob' if filepath else 'tree'

binderhub/static/js/index.js

@@ -346,9 +346,14 @@ function loadingMain(providerSpec) {
   if (path) {
     pathType = 'url';
   } else {
-    path = params.get('filepath');
+    path = params.get('labpath');
     if (path) {
-      pathType = 'file';
+      pathType = 'lab';
+    } else {
+      path = params.get('filepath');
+      if (path) {
+        pathType = 'file';
+      }
     }
   }
   build(providerSpec, log, fitAddon, path, pathType);

binderhub/static/js/src/image.js

@@ -49,11 +49,16 @@ export default class BinderImage {
       url = url.replace(/\/$/, "");
       // trim leading '/'
       path = path.replace(/(^\/)/g, "");
-      if (pathType === "file") {
+      if (pathType === "lab") {
         // trim trailing / on file paths
         path = path.replace(/(\/$)/g, "");
         // /doc/tree is safe because it allows redirect to files
         url = url + "/doc/tree/" + encodeURI(path);
+      } else if (pathType === "file") {
+        // trim trailing / on file paths
+        path = path.replace(/(\/$)/g, "");
+        // /tree is safe because it allows redirect to files
+        url = url + "/tree/" + encodeURI(path);
       } else {
         // pathType === 'url'
         url = url + "/" + path;

binderhub/static/js/src/path.js

@@ -1,7 +1,14 @@
 export function getPathType() {
   // return path type. 'file' or 'url'
   const element = document.getElementById("url-or-file-selected");
-  return element.innerText.trim().toLowerCase();
+  let pathType = element.innerText.trim().toLowerCase();
+  if (pathType === "file") {
+    // selecting a 'file' in the form opens with jupyterlab
+    // avoids backward-incompatibility with old `filepath` urls,
+    // which still open old UI
+    pathType = "lab";
+  }
+  return pathType;
 }
 
 export function updatePathText() {