Refactor our migrate command monkeypatching

src/pretix/base/management/commands/_migrations.py

@@ -0,0 +1,46 @@
+"""
+Django, for theoretically very valid reasons, creates migrations for *every single thing*
+we change on a model. Even the `help_text`! This makes sense, as we don't know if any
+database backend unknown to us might actually use this information for its database schema.
+
+However, pretix only supports PostgreSQL, MySQL, MariaDB and SQLite and we can be pretty
+certain that some changes to models will never require a change to the database. In this case,
+not creating a migration for certain changes will save us some performance while applying them
+*and* allow for a cleaner git history. Win-win!
+
+Only caveat is that we need to do some dirty monkeypatching to achieve it...
+"""
+from django.db import models
+from django.db.migrations.operations import models as modelops
+from django_countries.fields import CountryField
+
+
+def monkeypatch_migrations():
+    modelops.AlterModelOptions.ALTER_OPTION_KEYS.remove("verbose_name")
+    modelops.AlterModelOptions.ALTER_OPTION_KEYS.remove("verbose_name_plural")
+    modelops.AlterModelOptions.ALTER_OPTION_KEYS.remove("ordering")
+    modelops.AlterModelOptions.ALTER_OPTION_KEYS.remove("get_latest_by")
+    modelops.AlterModelOptions.ALTER_OPTION_KEYS.remove("default_manager_name")
+    modelops.AlterModelOptions.ALTER_OPTION_KEYS.remove("permissions")
+    modelops.AlterModelOptions.ALTER_OPTION_KEYS.remove("default_permissions")
+    IGNORED_ATTRS = [
+        # (field type, attribute name, banlist of field sub-types)
+        (models.Field, 'verbose_name', []),
+        (models.Field, 'help_text', []),
+        (models.Field, 'validators', []),
+        (models.Field, 'editable', [models.DateField, models.DateTimeField, models.DateField, models.BinaryField]),
+        (models.Field, 'blank', [models.DateField, models.DateTimeField, models.AutoField, models.NullBooleanField,
+                                 models.TimeField]),
+        (models.CharField, 'choices', [CountryField])
+    ]
+
+    original_deconstruct = models.Field.deconstruct
+
+    def new_deconstruct(self):
+        name, path, args, kwargs = original_deconstruct(self)
+        for ftype, attr, banlist in IGNORED_ATTRS:
+            if isinstance(self, ftype) and not any(isinstance(self, ft) for ft in banlist):
+                kwargs.pop(attr, None)
+        return name, path, args, kwargs
+
+    models.Field.deconstruct = new_deconstruct