Django performance with M2M

I have a model that looks like this:

class ParentObject(models.Model):
  ...
  services = models.ManyToManyField(Service)

class ChildObject(models.Model):
  parent = models.ForeignKey(ParentObject)
  services = models.ManyToManyField(Service)

class Service(models.Model):
  name开发者_JAVA技巧 = ...
  description = ...

So, in summary, an object has a list of Services attached and a child objects has to have other Services attached.

In size, each Parent has a list of 50-60 Services and each Child (5 per Parent) has a list of 30-40 Services. In django-admin (using grappelli btw) I have set Child to inline.

The problem is that the page in admin loads very hard (3-5 seconds) because Django Admin executes about 1200 queries (to get the Service each time - sometimes multiple times) to show me the information to edit.

Do you know any tips/tricks to optimize this?

Thank you in advance.

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I haven't been playing with grappelli but in standard django-admin I would consider usage of: ModelAdmin.raw_id_fields. The limitation is that you don't select services using name but using pk.

By default, Django's admin uses a select-box interface () for fields that are ForeignKey. Sometimes you don't want to incur the overhead of having to select all the related instances to display in the drop-down.

raw_id_fields is a list of fields you would like to change into an Input widget for either a ForeignKey or ManyToManyField:

class ArticleAdmin(admin.ModelAdmin):
    raw_id_fields = ("newspaper",)

Harder approach would be to override admin manager for Service and add request level cache. Remember to make this manager available in case of elated objects access.

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You need to override the admin queryset method and add a select_related in it, put this in your admin.py file

class ServiceAdmin(admin.ModelAdmin):
    ...

    def queryset(self, request):
        qs = super(ServiceAdmin, self).queryset(request)
        return qs.select_related()

admin.site.register(Service, ServiceAdmin)

This alone should decrease your queries a little bit, but the main problem is that the Django select_related doesn't follow ManyToMany automatically. You need to do some extra workaround for that. I would use the prefill_entry_list from the FeinCMS application to do that.