ManyToMany relation with intermediate model breaks import
See original GitHub issueLet’s say I need to modify the example app to add a field on the relation table between a book and a category:
# models.py
@python_2_unicode_compatible
class Category(models.Model):
name = models.CharField(max_length=100)
def __str__(self):
return self.name
@python_2_unicode_compatible
class Book(models.Model):
name = models.CharField('Book name', max_length=100)
author = models.ForeignKey(Author, blank=True, null=True)
author_email = models.EmailField('Author email', max_length=75, blank=True)
imported = models.BooleanField(default=False)
published = models.DateField('Published', blank=True, null=True)
price = models.DecimalField(max_digits=10, decimal_places=2, null=True,
blank=True)
categories = models.ManyToManyField(Category, blank=True,
through="IntermediateRelation")
def __str__(self):
return self.name
@python_2_unicode_compatible
class IntermediateRelation(models.Model):
relation_field = models.CharField(max_length=100)
category = models.ForeignKey(Category)
book = models.ForeignKey(Book)
def __str__(self):
return self.relation_field
Then I update admin.py
so that I can assign a category to a book in the admin:
class IntermediateRelationInline(admin.TabularInline):
model = IntermediateRelation
extra = 1
class BookAdmin(ImportExportMixin, admin.ModelAdmin):
list_filter = ['categories', 'author']
inlines = (IntermediateRelationInline, )
I can export my books, but when I try to import them back, here is what I get:
Traceback:
File "/home/synext/lib/python2.7/site-packages/Django-1.7-py2.7.egg/django/core/handlers/base.py" in get_response
111. response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/home/synext/lib/python2.7/site-packages/Django-1.7-py2.7.egg/django/utils/decorators.py" in _wrapped_view
105. response = view_func(request, *args, **kwargs)
File "/home/synext/lib/python2.7/site-packages/Django-1.7-py2.7.egg/django/views/decorators/cache.py" in _wrapped_view_func
52. response = view_func(request, *args, **kwargs)
File "/home/synext/lib/python2.7/site-packages/Django-1.7-py2.7.egg/django/contrib/admin/sites.py" in inner
204. return view(request, *args, **kwargs)
File "../import_export/admin.py" in process_import
130. raise_errors=True)
File "../import_export/resources.py" in import_data
355. six.reraise(*sys.exc_info())
File "../import_export/resources.py" in import_data
342. self.save_m2m(instance, row, real_dry_run)
File "../import_export/resources.py" in save_m2m
216. self.import_field(field, obj, data)
File "../import_export/resources.py" in import_field
195. field.save(obj, data)
File "../import_export/fields.py" in save
94. setattr(obj, self.attribute, self.clean(data))
File "/home/synext/lib/python2.7/site-packages/Django-1.7-py2.7.egg/django/db/models/fields/related.py" in __set__
1170. raise AttributeError("Cannot set values on a ManyToManyField which specifies an intermediary model. Use %s.%s's Manager instead." % (opts.app_label, opts.object_name))
Exception Type: AttributeError at /admin/core/book/process_import/
Exception Value: Cannot set values on a ManyToManyField which specifies an intermediary model. Use core.IntermediateRelation's Manager instead.
Issue Analytics
- State:
- Created 9 years ago
- Comments:9 (2 by maintainers)
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@amarandon Thank you, that was extremely helpful.
Just a note on your is_m2m_with_intermediate_object and get_intermediate_model functions: _meta.get_field_by_name has been deprecated and will be removed soon.
You can use _meta.get_field instead. Eg:
I managed to get it working. I’m posting what I’ve got so far for the record:
Some of this code is specific to the project I’m working on, for instance the
related_object_representation
method that has a couple of hardcoded fields but it should be possible to adapt.