Info plugin can filter properties in output

Resolves #1287

beetsplug/info.py

@@ -19,6 +19,7 @@ from __future__ import (division, absolute_import, print_function,
                         unicode_literals)
 
 import os
+import re
 
 from beets.plugins import BeetsPlugin
 from beets import ui
@@ -77,7 +78,7 @@ def update_summary(summary, tags):
 
 
 def print_data(data):
-    path = data.pop('path')
+    path = data.pop('path', None)
     formatted = {}
     for key, value in data.iteritems():
         if isinstance(value, list):
@@ -85,6 +86,9 @@ def print_data(data):
         if value is not None:
             formatted[key] = value
 
+    if len(formatted) == 0:
+        return
+
     maxwidth = max(len(key) for key in formatted)
     lineformat = u'{{0:>{0}}}: {{1}}'.format(maxwidth)
 
@@ -107,6 +111,9 @@ class InfoPlugin(BeetsPlugin):
                               help='show library fields instead of tags')
         cmd.parser.add_option('-s', '--summarize', action='store_true',
                               help='summarize the tags of all files')
+        cmd.parser.add_option('-i', '--include-keys', default=[],
+                              action='append', dest='included_keys',
+                              help='comma separated list of keys to show')
         return [cmd]
 
     def run(self, lib, opts, args):
@@ -128,6 +135,11 @@ class InfoPlugin(BeetsPlugin):
         else:
             data_collector = tag_data
 
+        included_keys = []
+        for keys in opts.included_keys:
+            included_keys.extend(keys.split(','))
+        key_filter = make_key_filter(included_keys)
+
         first = True
         summary = {}
         for data_emitter in data_collector(lib, ui.decargs(args)):
@@ -137,6 +149,9 @@ class InfoPlugin(BeetsPlugin):
                 self._log.error(u'cannot read file: {0}', ex)
                 continue
 
+            path = data.get('path')
+            data = key_filter(data)
+            data['path'] = path  # always show path
             if opts.summarize:
                 update_summary(summary, data)
             else:
@@ -147,3 +162,33 @@ class InfoPlugin(BeetsPlugin):
 
         if opts.summarize:
             print_data(summary)
+
+
+def make_key_filter(include):
+    """Return a function that filters a dictionary.
+
+    The returned filter takes a dictionary and returns another
+    dictionary that only includes the key-value pairs where the key
+    glob-matches one of the keys in `include`.
+    """
+    if not include:
+        return identity
+
+    matchers = []
+    for key in include:
+        key = re.escape(key)
+        key = key.replace(r'\*', '.*')
+        matchers.append(re.compile(key + '$'))
+
+    def filter(data):
+        filtered = dict()
+        for key, value in data.items():
+            if any(map(lambda m: m.match(key), matchers)):
+                filtered[key] = value
+        return filtered
+
+    return filter
+
+
+def identity(val):
+    return val

docs/changelog.rst

@@ -35,6 +35,8 @@ Features:
   ``art_filename`` configuration option. :bug:`1258`
 * :doc:`/plugins/fetchart`: There's a new Wikipedia image source that uses
   DBpedia to find albums. Thanks to Tom Jaspers. :bug:`1194`
+* :doc:`/plugins/info`: New options ``-i`` to display only given
+  properties. :bug:`1287`
 
 Core changes:
 

docs/plugins/info.rst

@@ -18,7 +18,18 @@ your library::
 
     $ beet info beatles
 
-Command-line options include:
+If you just want to see specific properties you can use the
+``--include-keys`` option to filter them. The argument is a
+comma-separated list of simple glob patterns where ``*`` matches any
+string. For example::
+
+    $ beet info -i 'title,mb*' beatles
+
+Will only show the ``title`` property and all properties starting with
+``mb``. You can add the ``-i`` option multiple times to the command
+line.
+
+Additional command-line options include:
 
 * ``--library`` or ``-l``: Show data from the library database instead of the
   files' tags.

test/helper.py

@@ -407,7 +407,7 @@ class TestHelper(object):
     def run_with_output(self, *args):
         with capture_stdout() as out:
             self.run_command(*args)
-        return out.getvalue()
+        return out.getvalue().decode('utf-8')
 
     # Safe file operations
 

test/test_info.py

@@ -19,6 +19,7 @@ from test._common import unittest
 from test.helper import TestHelper
 
 from beets.mediafile import MediaFile
+from beets.util import displayable_path
 
 
 class InfoTest(unittest.TestCase, TestHelper):
@@ -52,17 +53,17 @@ class InfoTest(unittest.TestCase, TestHelper):
         self.assertNotIn('composer:', out)
 
     def test_item_query(self):
-        items = self.add_item_fixtures(count=2)
-        items[0].album = 'xxxx'
-        items[0].write()
-        items[0].album = 'yyyy'
-        items[0].store()
+        item1, item2 = self.add_item_fixtures(count=2)
+        item1.album = 'xxxx'
+        item1.write()
+        item1.album = 'yyyy'
+        item1.store()
 
         out = self.run_with_output('album:yyyy')
-        self.assertIn(items[0].path, out)
-        self.assertIn(b'album: xxxx', out)
+        self.assertIn(displayable_path(item1.path), out)
+        self.assertIn(u'album: xxxx', out)
 
-        self.assertNotIn(items[1].path, out)
+        self.assertNotIn(displayable_path(item2.path), out)
 
     def test_item_library_query(self):
         item, = self.add_item_fixtures()
@@ -70,8 +71,8 @@ class InfoTest(unittest.TestCase, TestHelper):
         item.store()
 
         out = self.run_with_output('--library', 'album:xxxx')
-        self.assertIn(item.path, out)
-        self.assertIn(b'album: xxxx', out)
+        self.assertIn(displayable_path(item.path), out)
+        self.assertIn(u'album: xxxx', out)
 
     def test_collect_item_and_path(self):
         path = self.create_mediafile_fixture()
@@ -88,9 +89,18 @@ class InfoTest(unittest.TestCase, TestHelper):
         mediafile.save()
 
         out = self.run_with_output('--summarize', 'album:AAA', path)
-        self.assertIn('album: AAA', out)
-        self.assertIn('tracktotal: 5', out)
-        self.assertIn('title: [various]', out)
+        self.assertIn(u'album: AAA', out)
+        self.assertIn(u'tracktotal: 5', out)
+        self.assertIn(u'title: [various]', out)
+
+    def test_include_pattern(self):
+        item = self.add_item(album='xxxx')
+
+        out = self.run_with_output('--library', 'album:xxxx',
+                                   '--include-keys', '*lbu*')
+        self.assertIn(displayable_path(item.path), out)
+        self.assertNotIn(u'title:', out)
+        self.assertIn(u'album: xxxx', out)
 
 
 def suite():