Simple Mongo -> SQL migration tool

This is just a start at a Migration tool from Mongo to SQL.
It fills all currently available SQL models with data from
MongoDB. A few fields in the SQL tables are left out,
because some data format migrations are needed (notably:
queue_file_name).

This thing lives in mediagoblin/db/sql/convert.py because
it has a lot of stuff hardcoded and is not, repeat not for
end users!

Hard coded:
- output database: ./mediagoblin.db (sqlite)
- Mediagoblin config: ./mediagoblin.ini

mediagoblin/db/sql/convert.py

@@ -0,0 +1,143 @@
+from sqlalchemy import create_engine
+from sqlalchemy.orm import sessionmaker
+
+from mediagoblin.init import setup_global_and_app_config, setup_database
+from mediagoblin.db.util import ObjectId
+
+from mediagoblin.db.sql.models import (Base, User, MediaEntry, MediaComment,
+    Tag, MediaTag)
+
+Session = sessionmaker()
+
+
+obj_id_table = dict()
+
+def add_obj_ids(entry, new_entry):
+    global obj_id_table
+    print "%r -> %r" % (entry._id, new_entry.id)
+    obj_id_table[entry._id] = new_entry.id
+
+
+def copy_attrs(entry, new_entry, attr_list):
+    for a in attr_list:
+        val = entry[a]
+        setattr(new_entry, a, val)
+
+def copy_reference_attr(entry, new_entry, ref_attr):
+    val = entry[ref_attr]
+    val = obj_id_table[val]
+    setattr(new_entry, ref_attr, val)
+
+
+def convert_users(mk_db):
+    session = Session()
+
+    for entry in mk_db.User.find():
+        print entry.username
+
+        new_entry = User()
+        copy_attrs(entry, new_entry,
+            ('username', 'email', 'created', 'pw_hash', 'email_verified',
+             'status', 'verification_key', 'is_admin', 'url',
+             'bio', 'bio_html',
+             'fp_verification_key', 'fp_token_expire',))
+        # new_entry.fp_verification_expire = entry.fp_token_expire
+
+        session.add(new_entry)
+        session.flush()
+        add_obj_ids(entry, new_entry)
+
+    session.commit()
+    session.close()
+
+
+def convert_media_entries(mk_db):
+    session = Session()
+
+    for entry in mk_db.MediaEntry.find():
+        print repr(entry.title)
+
+        new_entry = MediaEntry()
+        copy_attrs(entry, new_entry,
+            ('title', 'slug', 'created',
+             'description', 'description_html',
+             'media_type',
+             'fail_error',
+             'queued_task_id',))
+        copy_reference_attr(entry, new_entry, "uploader")
+
+        session.add(new_entry)
+        session.flush()
+        add_obj_ids(entry, new_entry)
+
+    session.commit()
+    session.close()
+
+
+def convert_media_tags(mk_db):
+    session = Session()
+    session.autoflush = False
+
+    for media in mk_db.MediaEntry.find():
+        print repr(media.title)
+
+        for otag in media.tags:
+            print "  ", repr((otag["slug"], otag["name"]))
+
+            nslug = session.query(Tag).filter_by(slug=otag["slug"]).first()
+            print "     ", repr(nslug)
+            if nslug is None:
+                nslug = Tag(slug=otag["slug"])
+                session.add(nslug)
+                session.flush()
+            print "     ", repr(nslug), nslug.id
+
+            ntag = MediaTag()
+            ntag.tag = nslug.id
+            ntag.name = otag["name"]
+            ntag.media_entry = obj_id_table[media._id]
+            session.add(ntag)
+
+    session.commit()
+    session.close()
+
+
+def convert_media_comments(mk_db):
+    session = Session()
+
+    for entry in mk_db.MediaComment.find():
+        print repr(entry.content)
+
+        new_entry = MediaComment()
+        copy_attrs(entry, new_entry,
+            ('created',
+             'content', 'content_html',))
+        copy_reference_attr(entry, new_entry, "media_entry")
+        copy_reference_attr(entry, new_entry, "author")
+
+        session.add(new_entry)
+        session.flush()
+        add_obj_ids(entry, new_entry)
+
+    session.commit()
+    session.close()
+
+
+def main():
+    engine = create_engine('sqlite:///mediagoblin.db', echo=True)
+    Session.configure(bind=engine)
+
+    setup_global_and_app_config("mediagoblin.ini")
+
+    mk_conn, mk_db = setup_database()
+
+    Base.metadata.create_all(engine)
+
+    convert_users(mk_db)
+    convert_media_entries(mk_db)
+    convert_media_tags(mk_db)
+    convert_media_comments(mk_db)
+
+
+if __name__ == '__main__':
+    main()