177 lines
5.6 KiB
Python
177 lines
5.6 KiB
Python
import json
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from django.core import checks
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from django.db.models import NOT_PROVIDED, Field
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from django.db.models.expressions import ColPairs
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from django.db.models.fields.tuple_lookups import (
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TupleExact,
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TupleGreaterThan,
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TupleGreaterThanOrEqual,
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TupleIn,
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TupleIsNull,
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TupleLessThan,
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TupleLessThanOrEqual,
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)
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from django.utils.functional import cached_property
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class AttributeSetter:
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def __init__(self, name, value):
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setattr(self, name, value)
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class CompositeAttribute:
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def __init__(self, field):
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self.field = field
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@property
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def attnames(self):
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return [field.attname for field in self.field.fields]
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def __get__(self, instance, cls=None):
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return tuple(getattr(instance, attname) for attname in self.attnames)
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def __set__(self, instance, values):
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attnames = self.attnames
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length = len(attnames)
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if values is None:
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values = (None,) * length
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if not isinstance(values, (list, tuple)):
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raise ValueError(f"{self.field.name!r} must be a list or a tuple.")
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if length != len(values):
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raise ValueError(f"{self.field.name!r} must have {length} elements.")
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for attname, value in zip(attnames, values):
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setattr(instance, attname, value)
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class CompositePrimaryKey(Field):
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descriptor_class = CompositeAttribute
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def __init__(self, *args, **kwargs):
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if (
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not args
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or not all(isinstance(field, str) for field in args)
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or len(set(args)) != len(args)
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):
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raise ValueError("CompositePrimaryKey args must be unique strings.")
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if len(args) == 1:
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raise ValueError("CompositePrimaryKey must include at least two fields.")
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if kwargs.get("default", NOT_PROVIDED) is not NOT_PROVIDED:
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raise ValueError("CompositePrimaryKey cannot have a default.")
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if kwargs.get("db_default", NOT_PROVIDED) is not NOT_PROVIDED:
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raise ValueError("CompositePrimaryKey cannot have a database default.")
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if kwargs.get("db_column", None) is not None:
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raise ValueError("CompositePrimaryKey cannot have a db_column.")
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if kwargs.setdefault("editable", False):
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raise ValueError("CompositePrimaryKey cannot be editable.")
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if not kwargs.setdefault("primary_key", True):
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raise ValueError("CompositePrimaryKey must be a primary key.")
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if not kwargs.setdefault("blank", True):
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raise ValueError("CompositePrimaryKey must be blank.")
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self.field_names = args
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super().__init__(**kwargs)
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def deconstruct(self):
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# args is always [] so it can be ignored.
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name, path, _, kwargs = super().deconstruct()
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return name, path, self.field_names, kwargs
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@cached_property
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def fields(self):
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meta = self.model._meta
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return tuple(meta.get_field(field_name) for field_name in self.field_names)
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@cached_property
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def columns(self):
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return tuple(field.column for field in self.fields)
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def contribute_to_class(self, cls, name, private_only=False):
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super().contribute_to_class(cls, name, private_only=private_only)
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cls._meta.pk = self
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setattr(cls, self.attname, self.descriptor_class(self))
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def get_attname_column(self):
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return self.get_attname(), None
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def __iter__(self):
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return iter(self.fields)
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def __len__(self):
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return len(self.field_names)
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@cached_property
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def cached_col(self):
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return ColPairs(self.model._meta.db_table, self.fields, self.fields, self)
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def get_col(self, alias, output_field=None):
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if alias == self.model._meta.db_table and (
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output_field is None or output_field == self
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):
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return self.cached_col
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return ColPairs(alias, self.fields, self.fields, output_field)
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def get_pk_value_on_save(self, instance):
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values = []
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for field in self.fields:
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value = field.value_from_object(instance)
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if value is None:
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value = field.get_pk_value_on_save(instance)
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values.append(value)
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return tuple(values)
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def _check_field_name(self):
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if self.name == "pk":
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return []
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return [
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checks.Error(
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"'CompositePrimaryKey' must be named 'pk'.",
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obj=self,
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id="fields.E013",
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)
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]
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def value_to_string(self, obj):
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values = []
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vals = self.value_from_object(obj)
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for field, value in zip(self.fields, vals):
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obj = AttributeSetter(field.attname, value)
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values.append(field.value_to_string(obj))
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return json.dumps(values, ensure_ascii=False)
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def to_python(self, value):
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if isinstance(value, str):
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# Assume we're deserializing.
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vals = json.loads(value)
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value = [
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field.to_python(val)
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for field, val in zip(self.fields, vals, strict=True)
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]
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return value
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CompositePrimaryKey.register_lookup(TupleExact)
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CompositePrimaryKey.register_lookup(TupleGreaterThan)
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CompositePrimaryKey.register_lookup(TupleGreaterThanOrEqual)
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CompositePrimaryKey.register_lookup(TupleLessThan)
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CompositePrimaryKey.register_lookup(TupleLessThanOrEqual)
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CompositePrimaryKey.register_lookup(TupleIn)
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CompositePrimaryKey.register_lookup(TupleIsNull)
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def unnest(fields):
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result = []
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for field in fields:
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if isinstance(field, CompositePrimaryKey):
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result.extend(field.fields)
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else:
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result.append(field)
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return result
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