[Django]-How to limit django admin inline formsets

http://docs.djangoproject.com/en/dev/ref/contrib/admin/#inlinemodeladmin-options

Specify max_num in your Inline definition to limit the number.

extra specifies how many blank inlines to show.

Is the 1 inline required? As in you want to trigger a validation error if table B isn’t filled with at least 1 row?

The enabling / disabling of the add button in an inline is managed through the _has_add_permission method

you could add to your inline class:

def _has_add_permission(self, request, obj=None):
   # add/remove possibility to add a line to an inline
    if obj.table_b_items.count() < 5:
        return True
    else:
        return False