I'm trying to get the related_name of a many-to-many-field. The m2m-field is located betweeen the models "Group" and "Lection" and is defined in the group-model as following:
lections = models.ManyToManyField(Lection, blank=True)
The field looks like this:
<django.db.models.fields.related.ManyToManyField object at 0x012AD690>
The print of field.__dict__
is:
{'_choices': [],
'_m2m_column_cache': 'group_id',
'_m2m_name_cache': 'group',
'_m2m_reverse_column_cache': 'lection_id',
'_m2m_reverse_name_cache': 'lection',
'_unique': False,
'attname': 'lections',
'auto_created': False,
'blank': True,
'column': 'lections',
'creation_counter': 71,
'db_column': None,
'db_index': False,
'db_table': None,
'db_tablespace': '',
'default': <class django.db.models.fields.NOT_PROVIDED at 0x00FC8780>,
'editable': True,
'error_messages': {'blank': <django.utils.functional.__proxy__ object at 0x00FC
7B50>,
'invalid_choice': <django.utils.functional.__proxy__ object
at 0x00FC7A50>,
'null': <django.utils.functional.__proxy__ object at 0x00FC7
A70>},
'help_text': <django.utils.functional.__proxy__ object at 0x012AD6F0>,
'm2m_column_name': <function _curried at 0x012A88F0>,
'm2m_db_table': <function _curried at 0x012A8AF0>,
'm2m_field_name': <function _curried at 0x012A8970>,
'm2m_reverse_field_name': <function _curried at 0x012A89B0>,
'm2m_reverse_name': <function _curried at 0x012A8930>,
'max_length': None,
'name': 'lections',
'null': False,
'primary_key': False,
'rel': <django.db.models.fields.related.ManyToManyRel object at 0x012AD6B0>,
'related': <RelatedObject: mymodel:group related to lections>,
'related_query_name': <function _curried at 0x012A8670>,
'serialize': True,
'unique_for_date': None,
'unique_for_month': None,
'unique_for_year': None,
'validators': [],
'verbose_name': 'lections'}
Now the field should be accessed via a lection-instance. So this is done by lection.group_set
But i need to access it dynamically, so there is the need to get the related_name attribute from somewhere.
Here in the documentation, there is a note that it is 开发者_StackOverflow中文版possible to access ManyToManyField.related_name
, but this doesn't work for my somehow..
Help would be a lot appreciated. Thanks in advance.
Edit: Is there a need to put a class above all my models, which specifies the related_name attribute and so, every model has a similar name? like here maybe? -> docs.djangoproject.com/en/dev/topics/db/models/#be-careful-with-related-name
Try:
field.related_query_name()
What you pasted is basically:
>>> f = models.ManyToManyField(...)
>>> dir(f)
(...)
What you probably need, is to get an actual model class containing that field:
class MyModel(models.Model):
my_field = models.ManyToManyField(..., related_name='some_related_name')
-- and then you can do:
>>> MyModel._meta.get_field_by_name('my_field')[0].related_query_name()
'some_related_name'
I've used object.yourmanagerclass.join_table
in the past, but note that this returns a quoted string
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