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76 lines
3.0 KiB
Python
76 lines
3.0 KiB
Python
from functools import partial
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from django.db import models
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from django.db.models.fields.related import (
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RECURSIVE_RELATIONSHIP_CONSTANT, ManyToManyDescriptor, RelatedField,
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create_many_to_many_intermediary_model,
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)
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class CustomManyToManyField(RelatedField):
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"""
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Ticket #24104 - Need to have a custom ManyToManyField,
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which is not an inheritor of ManyToManyField.
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"""
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many_to_many = True
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def __init__(self, to, db_constraint=True, swappable=True, related_name=None, related_query_name=None,
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limit_choices_to=None, symmetrical=None, through=None, through_fields=None, db_table=None, **kwargs):
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try:
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to._meta
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except AttributeError:
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to = str(to)
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kwargs['rel'] = models.ManyToManyRel(
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self, to,
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related_name=related_name,
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related_query_name=related_query_name,
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limit_choices_to=limit_choices_to,
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symmetrical=symmetrical if symmetrical is not None else (to == RECURSIVE_RELATIONSHIP_CONSTANT),
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through=through,
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through_fields=through_fields,
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db_constraint=db_constraint,
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)
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self.swappable = swappable
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self.db_table = db_table
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if kwargs['rel'].through is not None and self.db_table is not None:
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raise ValueError(
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'Cannot specify a db_table if an intermediary model is used.'
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)
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super().__init__(
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related_name=related_name,
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related_query_name=related_query_name,
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limit_choices_to=limit_choices_to,
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**kwargs,
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)
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def contribute_to_class(self, cls, name, **kwargs):
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if self.remote_field.symmetrical and (
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self.remote_field.model == "self" or self.remote_field.model == cls._meta.object_name):
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self.remote_field.related_name = "%s_rel_+" % name
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super().contribute_to_class(cls, name, **kwargs)
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if not self.remote_field.through and not cls._meta.abstract and not cls._meta.swapped:
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self.remote_field.through = create_many_to_many_intermediary_model(self, cls)
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setattr(cls, self.name, ManyToManyDescriptor(self.remote_field))
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self.m2m_db_table = partial(self._get_m2m_db_table, cls._meta)
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def get_internal_type(self):
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return 'ManyToManyField'
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# Copy those methods from ManyToManyField because they don't call super() internally
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contribute_to_related_class = models.ManyToManyField.__dict__['contribute_to_related_class']
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_get_m2m_attr = models.ManyToManyField.__dict__['_get_m2m_attr']
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_get_m2m_reverse_attr = models.ManyToManyField.__dict__['_get_m2m_reverse_attr']
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_get_m2m_db_table = models.ManyToManyField.__dict__['_get_m2m_db_table']
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class InheritedManyToManyField(models.ManyToManyField):
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pass
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class MediumBlobField(models.BinaryField):
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"""
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A MySQL BinaryField that uses a different blob size.
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"""
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def db_type(self, connection):
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return 'MEDIUMBLOB'
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