Fix #5518 (EPUB: Unable to clear or delete series and update file series meta data when saving to disk)

src/calibre/customize/__init__.py

@@ -236,6 +236,10 @@ class MetadataWriterPlugin(Plugin):
 
     type = _('Metadata writer')
 
+    def __init__(self, *args, **kwargs):
+        Plugin.__init__(self, *args, **kwargs)
+        self.apply_null = False
+
     def set_metadata(self, stream, mi, type):
         '''
         Set metadata for the file represented by stream (a file like object

src/calibre/customize/builtins.py

@@ -329,7 +329,7 @@ class EPUBMetadataWriter(MetadataWriterPlugin):
 
     def set_metadata(self, stream, mi, type):
         from calibre.ebooks.metadata.epub import set_metadata
-        set_metadata(stream, mi)
+        set_metadata(stream, mi, apply_null=self.apply_null)
 
 class LRFMetadataWriter(MetadataWriterPlugin):
 

src/calibre/customize/ui.py

@@ -187,6 +187,18 @@ class QuickMetadata(object):
 
 quick_metadata = QuickMetadata()
 
+class ApplyNullMetadata(object):
+
+    def __init__(self):
+        self.apply_null = False
+
+    def __enter__(self):
+        self.apply_null = True
+
+    def __exit__(self, *args):
+        self.apply_null = False
+
+apply_null_metadata = ApplyNullMetadata()
 
 def get_file_type_metadata(stream, ftype):
     mi = MetaInformation(None, None)
@@ -214,6 +226,7 @@ def set_file_type_metadata(stream, mi, ftype):
             if not is_disabled(plugin):
                 with plugin:
                     try:
+                        plugin.apply_null = apply_null_metadata.apply_null
                         plugin.set_metadata(stream, mi, ftype.lower().strip())
                         break
                     except:

src/calibre/ebooks/metadata/epub.py

@@ -182,13 +182,21 @@ def get_metadata(stream, extract_cover=True):
 def get_quick_metadata(stream):
     return get_metadata(stream, False)
 
-def set_metadata(stream, mi):
+def set_metadata(stream, mi, apply_null=False):
     stream.seek(0)
     reader = OCFZipReader(stream, root=os.getcwdu())
     mi = MetaInformation(mi)
     for x in ('guide', 'toc', 'manifest', 'spine'):
         setattr(mi, x, None)
     reader.opf.smart_update(mi)
+    if apply_null:
+        if not getattr(mi, 'series', None):
+            reader.opf.series = None
+        if not getattr(mi, 'tags', []):
+            reader.opf.tags = []
+        if not getattr(mi, 'isbn', None):
+            reader.opf.isbn = None
+
     newopf = StringIO(reader.opf.render())
     safe_replace(stream, reader.container[OPF.MIMETYPE], newopf)
 

src/calibre/ebooks/metadata/opf2.py

@@ -404,6 +404,10 @@ class MetadataField(object):
 
     def __set__(self, obj, val):
         elem = obj.get_metadata_element(self.name)
+        if val is None:
+            if elem is not None:
+                elem.getparent().remove(elem)
+            return
         if elem is None:
             elem = obj.create_metadata_element(self.name, is_dc=self.is_dc)
         obj.set_text(elem, unicode(val))
@@ -722,6 +726,11 @@ class OPF(object):
 
         def fset(self, val):
             matches = self.isbn_path(self.metadata)
+            if val is None:
+                if matches:
+                    for x in matches:
+                        x.getparent().remove(x)
+                    return
             if not matches:
                 attrib = {'{%s}scheme'%self.NAMESPACES['opf']: 'ISBN'}
                 matches = [self.create_metadata_element('identifier',

src/calibre/ebooks/metadata/worker.py

@@ -235,6 +235,7 @@ def save_book(task, library_path, path, recs, notification=lambda x,y:x):
     from calibre.library.database2 import LibraryDatabase2
     db = LibraryDatabase2(library_path)
     from calibre.library.save_to_disk import config, save_to_disk
+    from calibre.customize.ui import apply_null_metadata
     opts = config().parse()
     for name in recs:
         setattr(opts, name, recs[name])
@@ -244,5 +245,6 @@ def save_book(task, library_path, path, recs, notification=lambda x,y:x):
         notification((id, title, not failed, tb))
         return True
 
-    save_to_disk(db, task, path, opts, callback)
+    with apply_null_metadata:
+        save_to_disk(db, task, path, opts, callback)