Ability to sync differently named collections with each other (#423)

* Ability to sync differently named collections

* Fixes

* Fixes

* Add example

CHANGELOG.rst

@@ -16,6 +16,8 @@ Version 0.10.0
   have been added.
 - New global command line option `--config`, to specify an alternative config
   file. See :gh:`409`.
+- The ``collections`` parameter can now be used to synchronize
+  differently-named collections with each other.
 
 Version 0.9.3
 =============

docs/config.rst

@@ -64,6 +64,12 @@ Pair Section
   The special values ``"from a"`` and ``"from b"``, tell vdirsyncer to try
   autodiscovery on a specific storage.
 
+  If the collection you want to sync doesn't have the same name on each side,
+  you may also use a value of the form ``["config_name", "name_a", "name_b"]``.
+  This will synchronize the collection ``name_a`` on side A with the collection
+  ``name_b`` on side B. The ``config_name`` will be used for representation in
+  CLI arguments and logging.
+
   Examples:
 
   - ``collections = ["from b", "foo", "bar"]`` makes vdirsyncer synchronize the
@@ -72,6 +78,10 @@ Pair Section
   - ``collections = ["from b", from a"]`` makes vdirsyncer synchronize all
     existing collections on either side.
 
+  - ``collections = [["bar", "bar_a", "bar_b"], "foo"]`` makes vdirsyncer
+    synchronize ``bar_a`` from side A with ``bar_b`` from side B, and also
+    synchronize ``foo`` on both sides with each other.
+
 - ``conflict_resolution``: Optional, define how conflicts should be handled.  A
   conflict occurs when one item (event, task) changed on both sides since the
   last sync.

tests/cli/test_config.py

@@ -199,7 +199,4 @@ def test_invalid_collections_arg():
     with pytest.raises(exceptions.UserError) as excinfo:
         _read_config(f)
 
-    assert (
-        'Section `pair foobar`: `collections` parameter must be a list of '
-        'collection names (strings!) or `null`.'
-    ) in str(excinfo.value)
+    assert 'Expected string' in str(excinfo.value)

tests/cli/test_discover.py

@@ -81,3 +81,48 @@ def test_discover_on_unsupported_storage(tmpdir, runner):
     result = runner.invoke(['discover'])
     assert result.exception
     assert 'doesn\'t support collection discovery' in result.output
+
+
+def test_discover_different_collection_names(tmpdir, runner):
+    foo = tmpdir.mkdir('foo')
+    bar = tmpdir.mkdir('bar')
+    runner.write_with_general(dedent('''
+    [storage foo]
+    type = filesystem
+    fileext = .txt
+    path = {foo}
+
+    [storage bar]
+    type = filesystem
+    fileext = .txt
+    path = {bar}
+
+    [pair foobar]
+    a = foo
+    b = bar
+    collections = [
+        ["coll1", "coll_a1", "coll_b1"],
+        "coll2"
+     ]
+    ''').format(foo=str(foo), bar=str(bar)))
+
+    result = runner.invoke(['discover'], input='y\n' * 6)
+    assert not result.exception
+
+    coll_a1 = foo.join('coll_a1')
+    coll_b1 = bar.join('coll_b1')
+
+    assert coll_a1.exists()
+    assert coll_b1.exists()
+
+    result = runner.invoke(['sync'])
+    assert not result.exception
+
+    foo_txt = coll_a1.join('foo.txt')
+    foo_txt.write('BEGIN:VCALENDAR\nUID:foo\nEND:VCALENDAR')
+
+    result = runner.invoke(['sync'])
+    assert not result.exception
+
+    assert foo_txt.exists()
+    assert coll_b1.join('foo.txt').exists()

vdirsyncer/cli/config.py

@@ -66,17 +66,26 @@ def _validate_pair_section(pair_config):
     if collections is None:
         return
 
-    e = ValueError('`collections` parameter must be a list of collection '
-                   'names (strings!) or `null`.')
-
     if not isinstance(collections, list):
-        raise e
+        raise ValueError('`collections` parameter must be a list or `null`.')
 
-    if any(not isinstance(x, (text_type, bytes)) for x in collections):
-        raise e
+    collection_names = set()
 
-    if len(set(collections)) != len(collections):
-        raise ValueError('Duplicate values in collections parameter.')
+    for i, collection in enumerate(collections):
+        if isinstance(collection, (text_type, bytes)):
+            collection_name = collection
+        elif isinstance(collection, list) and \
+                len(collection) == 3 and \
+                all(isinstance(x, (text_type, bytes)) for x in collection):
+            collection_name = collection[0]
+        else:
+            raise ValueError('`collections` parameter, position {i}:'
+                             'Expected string or list of three strings.'
+                             .format(i=i))
+
+        if collection_name in collection_names:
+            raise ValueError('Duplicate values in collections parameter.')
+        collection_names.add(collection_name)
 
 
 def load_config(fname=None):

vdirsyncer/cli/utils.py

@@ -276,7 +276,7 @@ def _collections_for_pair_impl(status_path, pair):
         a_discovered = _discover_from_config(pair.config_a)
         b_discovered = _discover_from_config(pair.config_b)
 
-        for shortcut in set(shortcuts):
+        for shortcut in shortcuts:
             if shortcut == 'from a':
                 collections = a_discovered
             elif shortcut == 'from b':
@@ -285,17 +285,28 @@ def _collections_for_pair_impl(status_path, pair):
                 collections = [shortcut]
 
             for collection in collections:
-                try:
-                    a_args = a_discovered[collection]
-                except KeyError:
-                    a_args = _handle_collection_not_found(pair.config_a,
-                                                          collection)
+                if isinstance(collection, list):
+                    try:
+                        collection, collection_a, collection_b = collection
+                    except ValueError:
+                        raise exceptions.UserError(
+                            'Expected string or list of length 3, '
+                            '{} found instead.'
+                            .format(collection))
+                else:
+                    collection_a = collection_b = collection
 
                 try:
-                    b_args = b_discovered[collection]
+                    a_args = a_discovered[collection_a]
+                except KeyError:
+                    a_args = _handle_collection_not_found(pair.config_a,
+                                                          collection_a)
+
+                try:
+                    b_args = b_discovered[collection_b]
                 except KeyError:
                     b_args = _handle_collection_not_found(pair.config_b,
-                                                          collection)
+                                                          collection_b)
 
                 yield collection, (a_args, b_args)