Changed default collection naming

Also added upgrade text

docs/changelog.rst

@@ -5,6 +5,7 @@ Changelog
 Changes in dev
 ==============
 
+- Updated default collection naming convention
 - Added Document Mixin support
 - Fixed queryet __repr__ mid iteration
 - Added hint() support, so cantell Mongo the proper index to use for the query

docs/index.rst

@@ -2,7 +2,7 @@
 MongoEngine User Documentation
 ==============================
 
-MongoEngine is an Object-Document Mapper, written in Python for working with 
+MongoEngine is an Object-Document Mapper, written in Python for working with
 MongoDB. To install it, simply run
 
 .. code-block:: console
@@ -15,7 +15,7 @@ To get help with using MongoEngine, use the `MongoEngine Users mailing list
 <http://groups.google.com/group/mongoengine-users>`_ or come chat on the
 `#mongoengine IRC channel <irc://irc.freenode.net/mongoengine>`_.
 
-If you are interested in contributing, join the developers' `mailing list 
+If you are interested in contributing, join the developers' `mailing list
 <http://groups.google.com/group/mongoengine-dev>`_.
 
 .. toctree::
@@ -26,6 +26,7 @@ If you are interested in contributing, join the developers' `mailing list
    apireference
    django
    changelog
+   upgrading
 
 Indices and tables
 ==================

docs/upgrade.rst

@@ -0,0 +1,73 @@
+=========
+Upgrading
+=========
+
+0.4 to 0.5
+===========
+
+There have been the following backwards incompatibilities from 0.4 to 0.5:
+
+#. Default collection naming.
+
+Previously it was just lowercase, its now much more pythonic and readable as its
+lowercase and underscores, previously ::
+
+    class MyAceDocument(Document):
+        pass
+
+    MyAceDocument._meta['collection'] == myacedocument
+
+In 0.5 this will change to ::
+
+    class MyAceDocument(Document):
+        pass
+
+    MyAceDocument._get_collection_name() == my_ace_document
+
+To upgrade use a Mixin class to set meta like so ::
+
+    class BaseMixin(object):
+        meta = {
+            'collection': lambda c: c.__name__.lower()
+        }
+
+    class MyAceDocument(Document, BaseMixin):
+        pass
+
+    MyAceDocument._get_collection_name() == myacedocument
+
+Alternatively, you can rename your collections eg ::
+
+    from mongoengine.connection import _get_db
+    from mongoengine.base import _document_registry
+
+    def rename_collections():
+        db = _get_db()
+
+        failure = False
+
+        collection_names = [d._get_collection_name() for d in _document_registry.values()]
+
+        for new_style_name in collection_names:
+            if not new_style_name:  # embedded documents don't have collections
+                continue
+            old_style_name = new_style_name.replace('_', '')
+
+            if old_style_name == new_style_name:
+                continue  # Nothing to do
+
+            existing = db.collection_names()
+            if old_style_name in existing:
+                if new_style_name in existing:
+                    failure = True
+                    print "FAILED to rename: %s to %s (already exists)" % (
+                        old_style_name, new_style_name)
+                else:
+                    db[old_style_name].rename(new_style_name)
+                    print "Renamed:  %s to %s" % (old_style_name, new_style_name)
+
+        if failure:
+            print "Upgrading  collection names failed"
+        else:
+            print "Upgraded collection names"
+