Add update --all flag to update all collections add once

Closes #77

.flake8

@@ -1,3 +1,2 @@
 [flake8]
-max-line-length = 88
-extend-ignore = E203
+extend-ignore = E203, E501

CHANGELOG.md

@@ -1,6 +1,10 @@
 Change Log
 ==========
 
+## Upcoming
+* Add `--all` flag to update command which will update all configured
+  collections.
+
 ## v0.11.0 - 2023-06-06
 * Use the convert’s plugin [`thread` configuration][convert-config] when
   transcoding files. ([@johnyerhot](https://github.com/johnyerhot))

README.md

@@ -205,7 +205,13 @@ The command accepts the following option.
   command will ask you to confirm the creation of the external
   collection. These options specify the answer as a cli option.
 
+```plain
+beet alt update [--create|--no-create] --all
 ```
+
+Update all external collections defined in `alternatives` configuration.
+
+```plain
 beet alt list-tracks [--format=FORMAT] NAME
 ```
 

beetsplug/alternatives.py

@@ -53,12 +53,21 @@ def __init__(self):
     def commands(self):
         return [AlternativesCommand(self)]
 
-    def update(self, lib: Library, options):
-        try:
-            alt = self.alternative(options.name, lib)
-        except KeyError as e:
-            raise UserError("Alternative collection '{0}' not found.".format(e.args[0]))
-        alt.update(create=options.create)
+    def update(self, lib: Library, options: argparse.Namespace):
+        if options.name is None:
+            if not options.all:
+                raise UserError("Please specify a collection name or the --all flag")
+
+            for name in self.config.keys():
+                self.alternative(name, lib).update(create=options.create)
+        else:
+            try:
+                alt = self.alternative(options.name, lib)
+            except KeyError as e:
+                raise UserError(
+                    "Alternative collection '{0}' not found.".format(e.args[0])
+                )
+            alt.update(create=options.create)
 
     def list_tracks(self, lib, options):
         if options.format is not None:
@@ -100,11 +109,22 @@ def __init__(self, plugin):
 
         update = subparsers.add_parser("update")
         update.set_defaults(func=plugin.update)
-        update.add_argument("name", metavar="NAME")
+        update.add_argument(
+            "name",
+            metavar="NAME",
+            nargs="?",
+            help="Name of the collection. Must be  provided unless --all is given",
+        )
         update.add_argument("--create", action="store_const", dest="create", const=True)
         update.add_argument(
             "--no-create", action="store_const", dest="create", const=False
         )
+        update.add_argument(
+            "--all",
+            action="store_true",
+            default=False,
+            help="Update all alternative collections that are defined in the configuration",
+        )
 
         list_tracks = subparsers.add_parser(
             "list-tracks",

test/cli_test.py

@@ -415,6 +415,35 @@ def touch_art(item, image_path):
         item = album.items().get()
         self.assertHasEmbeddedArtwork(self.get_path(item), self.IMAGE_FIXTURE2)
 
+    def test_update_all(self):
+        dir_a = self.mkdtemp()
+        dir_b = self.mkdtemp()
+        self.config["alternatives"] = {
+            "a": {
+                "directory": dir_a,
+                "query": "myexternal:true",
+            },
+            "b": {
+                "directory": dir_b,
+                "query": "myexternal:true",
+            },
+        }
+
+        with self.assertRaises(UserError) as c:
+            self.runcli("alt", "update")
+        assert str(c.exception) == "Please specify a collection name or the --all flag"
+
+        item = self.add_track(title="a", myexternal="true")
+        self.runcli("alt", "update", "--all")
+        item.load()
+        path_a = self.get_path(item, path_key="alt.a")
+        assert path_a and dir_a in path_a.decode()
+        self.assertIsFile(path_a)
+
+        path_b = self.get_path(item, path_key="alt.b")
+        assert path_b and dir_b in path_b.decode()
+        self.assertIsFile(path_b)
+
 
 class ExternalConvertTest(TestHelper):
     """Test alternatives with non-empty ``format`` option, i.e. transcoding