Keep track of changes to fields¶
In some circumstances, you want to keep track of changes made on some fields of the master model.
django-cqrs can send previous values of the tracked fields to replicas.
To do so, you can use the
CQRS_TRACKED_FIELDS attribute to specify which fields to track:
class MyMasterModel(MasterMixin): CQRS_ID = 'my_model' CQRS_TRACKED_FIELDS = ('char_field', 'parent', 'status') char_field = models.CharField(max_length=100) status = models.CharField(max_length=15, choices=STATUSES) parent = models.ForeignKey(ParentMode, on_delete=models.CASCADE)
This way, you can override the
cqrs_save and apply your persistence logic
based o tracked fields before accessing your database:
class MyReplicaModel(ReplicaMixin): CQRS_ID = 'my_model' @classmethod def cqrs_save(cls, master_data, previous_data=None, sync=False): # Custom logic based on previous_data here. pass
The fields tracking features honors the