34

I have this code

Task.objects.bulk_create(ces)

Now this is my signal

@receiver(pre_save, sender=Task)
def save_hours(sender, instance, *args, **kwargs):
    logger.debug('test')

Now this signal is not triggered in bulk create

I am using django 1.8

user3214546
  • 6,523
  • 13
  • 51
  • 98

2 Answers2

40

As mentioned bulk_create does not trigger these signals -

https://docs.djangoproject.com/en/1.8/ref/models/querysets/#bulk-create

This method inserts the provided list of objects into the database in an efficient manner (generally only 1 query, no matter how many objects there are).

This has a number of caveats though:

  • The model’s save() method will not be called, and the pre_save and post_save signals will not be sent.
  • It does not work with child models in a multi-table inheritance scenario.
  • If the model’s primary key is an AutoField it does not retrieve and set the primary key attribute, as save() does.
  • It does not work with many-to-many relationships.
  • The batch_size parameter controls how many objects are created in single query. The default is to create all objects in one batch, except for SQLite where the default is such that at most 999 variables per query are used.

So you have to trigger them manually. If you want this for all models you can override the bulk_create and send them yourself like this - 

class CustomManager(models.Manager):
    def bulk_create(items,....):
         super().bulk_create(...)
         for i in items:
              [......] # code to send signal

Then use this manager - 

class Task(models.Model):
    objects = CustomManager()
    ....
brainless coder
  • 6,310
  • 1
  • 20
  • 36
11

Iterating on the answer above:

Python 2:

class CustomManager(models.Manager):
    def bulk_create(self, objs, **kwargs):
        #Your code here
        return super(models.Manager,self).bulk_create(objs,**kwargs)

Python 3:

class CustomManager(models.Manager):
    def bulk_create(self, objs, **kwargs):
        #Your code here
        return super(CustomManager, self).bulk_create(objs,**kwargs)  

class Task(models.Model):
    objects = CustomManager()
    ....

Complete answer in python 2:

class CustomManager(models.Manager):

def bulk_create(self, objs, **kwargs):
    a = super(models.Manager,self).bulk_create(objs,**kwargs)
    for i in objs:
        post_save.send(i.__class__, instance=i, created=True)
    return a
Community
  • 1
  • 1
Felipe Sens
  • 111
  • 1
  • 3
  • 1
    Problem is if you would use 'ignore_conflicts=True' then you newer know how much instances are created in fact. It might be 15 of 20 for example, or 19, or 20 or None – Aleksei Khatkevich Jul 28 '20 at 12:36
  • 1
    `objs` might be an iterator, so a more robust code would first convert it into a list, then call super().bulk_create(...) and then iterate over the items in order to send the signals. – knaperek Feb 10 '21 at 19:55