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107 lines
3.2 KiB
Python
107 lines
3.2 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,
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ManyToManyDescriptor,
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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__(
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self,
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to,
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db_constraint=True,
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swappable=True,
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related_name=None,
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related_query_name=None,
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limit_choices_to=None,
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symmetrical=None,
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through=None,
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through_fields=None,
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db_table=None,
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**kwargs,
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):
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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,
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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=(
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symmetrical
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if symmetrical is not None
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else (to == RECURSIVE_RELATIONSHIP_CONSTANT)
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),
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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"
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or self.remote_field.model == cls._meta.object_name
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):
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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 (
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not self.remote_field.through
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and not cls._meta.abstract
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and not cls._meta.swapped
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):
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self.remote_field.through = create_many_to_many_intermediary_model(
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self, cls
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)
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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__[
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"contribute_to_related_class"
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]
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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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