easyid3: support saving as v2.3. Fixes #188

The EasyID3 class only supports working with a v2.4 file and frame
types. When saving we need update to v2.3 and then save. To
prevent the EasyID3 instance getting useless after saving we
save the state before and restore it afterwards.

mutagen/easyid3.py

@@ -16,7 +16,7 @@
 
 from ._compat import iteritems, text_type, PY2
 from mutagen import Metadata
-from mutagen._util import DictMixin, dict_match
+from mutagen._util import DictMixin, dict_match, loadfile
 from mutagen.id3 import ID3, error, delete, ID3FileType
 
 
@@ -172,10 +172,30 @@ def __init__(self, filename=None):
     load = property(lambda s: s.__id3.load,
                     lambda s, v: setattr(s.__id3, 'load', v))
 
-    def save(self, *args, **kwargs):
-        # ignore v2_version until we support 2.3 here
-        kwargs.pop("v2_version", None)
-        self.__id3.save(*args, **kwargs)
+    @loadfile(writable=True, create=True)
+    def save(self, filething, v1=1, v2_version=4, v23_sep='/', padding=None):
+        """save(filething=None, v1=1, v2_version=4, v23_sep='/', padding=None)
+
+        Save changes to a file.
+        See :meth:`mutagen.id3.ID3.save` for more info.
+        """
+
+        if v2_version == 3:
+            # EasyID3 only works with v2.4 frames, so update_to_v23() would
+            # break things. We have to save a shallow copy of all tags
+            # and restore it after saving. Due to CHAP/CTOC copying has
+            # to be done recursively implemented in ID3Tags.
+            backup = self.__id3._copy()
+            try:
+                self.__id3.update_to_v23()
+                self.__id3.save(
+                    filething, v1=v1, v2_version=v2_version, v23_sep=v23_sep,
+                    padding=padding)
+            finally:
+                self.__id3._restore(backup)
+        else:
+            self.__id3.save(filething, v1=v1, v2_version=v2_version,
+                            v23_sep=v23_sep, padding=padding)
 
     delete = property(lambda s: s.__id3.delete,
                       lambda s, v: setattr(s.__id3, 'delete', v))

mutagen/id3/_tags.py

@@ -478,6 +478,25 @@ def update_to_v23(self):
         for f in self.getall("CTOC"):
             f.sub_frames.update_to_v23()
 
+    def _copy(self):
+        """Creates a shallow copy of all tags"""
+
+        items = self.items()
+        subs = {}
+        for f in (self.getall("CHAP") + self.getall("CTOC")):
+            subs[f.HashKey] = f.sub_frames._copy()
+        return (items, subs)
+
+    def _restore(self, value):
+        """Restores the state copied with _copy()"""
+
+        items, subs = value
+        self.clear()
+        for key, value in items:
+            self[key] = value
+            if key in subs:
+                value.sub_frames._restore(subs[key])
+
 
 def save_frame(frame, name=None, config=None):
     if config is None:

tests/test_easyid3.py

@@ -4,7 +4,7 @@
 import pickle
 
 from mutagen import MutagenError
-from mutagen.id3 import ID3FileType, ID3, RVA2
+from mutagen.id3 import ID3FileType, ID3, RVA2, CHAP, TDRC, CTOC
 from mutagen.easyid3 import EasyID3, error as ID3Error
 from mutagen._compat import PY3
 
@@ -21,6 +21,15 @@ def setUp(self):
     def tearDown(self):
         os.unlink(self.filename)
 
+    def test_load_filename(self):
+        self.id3.save(self.filename)
+        self.id3.load(self.filename)
+        assert self.id3.filename == self.filename
+
+        path = os.path.join(DATA_DIR, 'silence-44-s.mp3')
+        new = EasyID3(path)
+        assert new.filename == path
+
     def test_txxx_latin_first_then_non_latin(self):
         self.id3["performer"] = [u"foo"]
         self.id3["performer"] = [u"\u0243"]
@@ -37,11 +46,42 @@ def test_remember_ctr(self):
         mp3.pprint()
         self.failUnless(isinstance(mp3.tags, EasyID3))
 
-    def test_ignore_23(self):
-        self.id3["date"] = "2004"
+    def test_save_23(self):
         self.id3.save(self.filename, v2_version=3)
+        self.assertEqual(ID3(self.filename).version, (2, 3, 0))
+        self.id3.save(self.filename, v2_version=4)
         self.assertEqual(ID3(self.filename).version, (2, 4, 0))
 
+    def test_save_date_v23(self):
+        self.id3["date"] = "2004"
+        assert self.realid3.getall("TDRC")[0] == u"2004"
+        self.id3.save(self.filename, v2_version=3)
+        assert self.realid3.getall("TDRC")[0] == u"2004"
+        assert not self.realid3.getall("TYER")
+        new = ID3(self.filename, translate=False)
+        assert new.version == (2, 3, 0)
+        assert new.getall("TYER")[0] == u"2004"
+
+    def test_save_v23_error_restore(self):
+        self.id3["date"] = "2004"
+        with self.assertRaises(MutagenError):
+            self.id3.save("", v2_version=3)
+        assert self.id3["date"] == ["2004"]
+
+    def test_save_v23_recurse_restore(self):
+        self.realid3.add(CHAP(sub_frames=[TDRC(text="2006")]))
+        self.realid3.add(CTOC(sub_frames=[TDRC(text="2006")]))
+        self.id3.save(self.filename, v2_version=3)
+
+        for frame_id in ["CHAP", "CTOC"]:
+            chap = self.realid3.getall(frame_id)[0]
+            assert chap.sub_frames.getall("TDRC")[0] == "2006"
+            new = ID3(self.filename, translate=False)
+            assert new.version == (2, 3, 0)
+            chap = new.getall(frame_id)[0]
+            assert not chap.sub_frames.getall("TDRC")
+            assert chap.sub_frames.getall("TYER")[0] == "2006"
+
     def test_delete(self):
         self.id3["artist"] = "foobar"
         self.id3.save(self.filename)