Fix 3.1 to 3.2 migration paths

awx/main/migrations/_squashed.py

@@ -0,0 +1,50 @@
+from itertools import chain
+from django.db import (
+    connection,
+    migrations,
+)
+
+
+def squash_data(SQUASHED):
+    '''Returns a tuple of the squashed_keys and the key position to begin
+    processing replace and operation lists'''
+
+    cm = current_migration()
+    squashed_keys = sorted(SQUASHED.keys())
+    try:
+        if cm is None:
+            key_index = 0
+        else:
+            key_index = squashed_keys.index(cm.name) + 1
+    except ValueError:
+        key_index = 0
+    return squashed_keys, key_index
+
+
+def current_migration():
+    '''Get the latest migration non-squashed migration'''
+    try:
+        recorder = migrations.recorder.MigrationRecorder(connection)
+        return recorder.migration_qs.filter(app='main').exclude(name__contains='squashed').latest('id')
+    except recorder.Migration.DoesNotExist:
+        return None
+
+
+def replaces(SQUASHED):
+    '''Build a list of replacement migrations based on the most recent non-squashed migration
+    and the provided list of SQUASHED migrations. If the most recent non-squashed migration
+    is not present anywhere in the SQUASHED dictionary, assume they have all been applied.
+    '''
+    squashed_keys, key_index = squash_data(SQUASHED)
+    return [(b'main', key) for key in squashed_keys[key_index:]]
+
+
+def operations(SQUASHED):
+    '''Build a list of migration operations based on the most recent non-squashed migration
+    and the provided list of SQUASHED migrations. If the most recent non-squashed migration
+    is not present anywhere in the SQUASHED dictionary, assume they have all been applied.
+    '''
+    squashed_keys, key_index = squash_data(SQUASHED)
+    op_keys = squashed_keys[key_index:]
+    ops = [SQUASHED[op_key] for op_key in op_keys]
+    return [op for op in chain.from_iterable(ops)]