I tried to create a project where to manage a garage, but when I create the model in application"utiliser", I got this problem. Thanks!
In your code, you are trying to assign string client as the default value for your ForeignKey. ForeignKeys are represented as integers and that is why you get this error. You can assign id value of the foreign object (if exists), or use null=True which will make default NULL. If there is no data at all in this object, then remove default value, migrations and flush database, then you will get not-nullable ForeignKey field.
