mbcollection: human-readable MB exceptions

Fixes #107 by wrapping the API invocation function with exception handlers.

beetsplug/mbcollection.py

@@ -23,6 +23,18 @@ from musicbrainzngs import musicbrainz
 
 SUBMISSION_CHUNK_SIZE = 200
 
+def mb_request(*args, **kwargs):
+    """Send a MusicBrainz API request and process exceptions.
+    """
+    try:
+        return musicbrainz._mb_request(*args, **kwargs)
+    except musicbrainzngs.AuthenticationError:
+        raise ui.UserError('authentication with MusicBrainz failed')
+    except musicbrainzngs.ResponseError as exc:
+        raise ui.UserError('MusicBrainz API error: {0}'.format(exc))
+    except musicbrainzngs.UsageError:
+        raise ui.UserError('MusicBrainz credentials missing')
+
 def submit_albums(collection_id, release_ids):
     """Add all of the release IDs to the indicated collection. Multiple
     requests are made if there are many release IDs to submit.
@@ -30,15 +42,16 @@ def submit_albums(collection_id, release_ids):
     for i in range(0, len(release_ids), SUBMISSION_CHUNK_SIZE):
         chunk = release_ids[i:i+SUBMISSION_CHUNK_SIZE]
         releaselist = ";".join(chunk)
-        musicbrainz._mb_request(
+        mb_request(
             "collection/%s/releases/%s" % (collection_id, releaselist),
-            'PUT', True, True, body='foo')
+            'PUT', True, True, body='foo'
+        )
         # A non-empty request body is required to avoid a 411 "Length
         # Required" error from the MB server.
 
 def update_collection(lib, opts, args):
     # Get the collection to modify.
-    collections = musicbrainz._mb_request('collection', 'GET', True, True)
+    collections = mb_request('collection', 'GET', True, True)
     if not collections['collection-list']:
         raise ui.UserError('no collections exist for user')
     collection_id = collections['collection-list'][0]['id']
@@ -60,7 +73,7 @@ class MusicBrainzCollectionPlugin(BeetsPlugin):
         super(MusicBrainzCollectionPlugin, self).__init__()
         musicbrainzngs.auth(
             config['musicbrainz']['user'].get(unicode),
-            config['musicbrainz']['pass'].get(unicode)
+            config['musicbrainz']['pass'].get(unicode),
         )
 
     def commands(self):

docs/changelog.rst

@@ -38,6 +38,8 @@ Other stuff:
   pathnames.
 * Fix a spurious warning from the Unidecode module when matching albums that
   are missing all metadata.
+* :doc:`/plugins/mbcollection`: Show friendly, human-readable errors when
+  MusicBrainz exceptions occur.
 
 1.1b2 (February 16, 2013)
 -------------------------