Django

Models

Migrations

Example 1

• change model type e.g. Char to Integer : psycopg2.errors.InvalidTextRepresentation: invalid input syntax for type integer: ""
• alter field name in model ...try to delete field ...errors...
• to fix, try to rename, remove ... delete col by hand using psql, delete migrations, recreate migration ...
• problems: stuck in errors psycopg2.errors.DuplicateColumn: column "ccc" of relation "rrr" already exists

Example 2

• change of field to unique can result in "DETAIL: Key (id....)=() is duplicated."

Example 3

• if changing CharField to Unique the migration maybe does not covert the emty values to None?NULL and then one gets problems like: https://stackoverflow.com/questions/17257031/django-unique-null-and-blank-charfield-giving-already-exists-error-on-admin-p