[migration] don't handle data deletion anymore on schema changes
In most cases when we want to drop some entity/relation type, we don't care
whether hooks are called on their deletion. There is even low chances that some
hooks still exists, based on an old version of the schema. Last but not least,
this is horribly inefficient.
So this should be clearly documented and handled by application's programmer if
desired.
This patch removes unnecessary deletion (because table or column will be later
dropped) and reimplements the case of partial deletion (only one relation
definition among several, hence the database structure isn't modified) using
sql.
Only one test regarding deletion of inlined relation def is added as other cases
seem to be covered by existing tests.
Closes #7023315
"""This module compare the Schema on the file system to the one in the database"""
from cStringIO import StringIO
from cubicweb.web.schemaviewer import SchemaViewer
from logilab.common.ureports import TextWriter
import difflib
viewer = SchemaViewer()
layout_db = viewer.visit_schema(schema, display_relations=True)
layout_fs = viewer.visit_schema(fsschema, display_relations=True)
writer = TextWriter()
stream_db = StringIO()
stream_fs = StringIO()
writer.format(layout_db, stream=stream_db)
writer.format(layout_fs, stream=stream_fs)
stream_db.seek(0)
stream_fs.seek(0)
db = stream_db.getvalue().splitlines()
fs = stream_fs.getvalue().splitlines()
open('db_schema.txt', 'w').write(stream_db.getvalue())
open('fs_schema.txt', 'w').write(stream_fs.getvalue())
#for diff in difflib.ndiff(fs, db):
# print diff