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Source code for django.db.models.options

from __future__ import unicode_literals

import warnings
from bisect import bisect
from collections import OrderedDict, defaultdict
from itertools import chain

from django.apps import apps
from django.conf import settings
from django.core.exceptions import FieldDoesNotExist
from django.db.models.fields import AutoField
from django.db.models.fields.proxy import OrderWrt
from django.db.models.fields.related import ManyToManyField
from django.utils import six
from django.utils.datastructures import ImmutableList, OrderedSet
from django.utils.deprecation import RemovedInDjango110Warning
from django.utils.encoding import (
    force_text, python_2_unicode_compatible, smart_text,
from django.utils.functional import cached_property
from django.utils.lru_cache import lru_cache
from django.utils.text import camel_case_to_spaces
from django.utils.translation import override, string_concat

PROXY_PARENTS = object()


    "The return type of '%s' should never be mutated. If you want to manipulate this list "
    "for your own use, make a copy first."

DEFAULT_NAMES = ('verbose_name', 'verbose_name_plural', 'db_table', 'ordering',
                 'unique_together', 'permissions', 'get_latest_by',
                 'order_with_respect_to', 'app_label', 'db_tablespace',
                 'abstract', 'managed', 'proxy', 'swappable', 'auto_created',
                 'index_together', 'apps', 'default_permissions',
                 'select_on_save', 'default_related_name')

class raise_deprecation(object):
    def __init__(self, suggested_alternative):
        self.suggested_alternative = suggested_alternative

    def __call__(self, fn):
        def wrapper(*args, **kwargs):
                "'%s is an unofficial API that has been deprecated. "
                "You may be able to replace it with '%s'" % (
                RemovedInDjango110Warning, stacklevel=2
            return fn(*args, **kwargs)
        return wrapper

def normalize_together(option_together):
    option_together can be either a tuple of tuples, or a single
    tuple of two strings. Normalize it to a tuple of tuples, so that
    calling code can uniformly expect that.
        if not option_together:
            return ()
        if not isinstance(option_together, (tuple, list)):
            raise TypeError
        first_element = next(iter(option_together))
        if not isinstance(first_element, (tuple, list)):
            option_together = (option_together,)
        # Normalize everything to tuples
        return tuple(tuple(ot) for ot in option_together)
    except TypeError:
        # If the value of option_together isn't valid, return it
        # verbatim; this will be picked up by the check framework later.
        return option_together

def make_immutable_fields_list(name, data):
    return ImmutableList(data, warning=IMMUTABLE_WARNING % name)

[docs]@python_2_unicode_compatible class Options(object): FORWARD_PROPERTIES = ('fields', 'many_to_many', 'concrete_fields', 'local_concrete_fields', '_forward_fields_map') REVERSE_PROPERTIES = ('related_objects', 'fields_map', '_relation_tree') def __init__(self, meta, app_label=None): self._get_fields_cache = {} self.proxied_children = [] self.local_fields = [] self.local_many_to_many = [] self.virtual_fields = [] self.model_name = None self.verbose_name = None self.verbose_name_plural = None self.db_table = '' self.ordering = [] self.unique_together = [] self.index_together = [] self.select_on_save = False self.default_permissions = ('add', 'change', 'delete') self.permissions = [] self.object_name = None self.app_label = app_label self.get_latest_by = None self.order_with_respect_to = None self.db_tablespace = settings.DEFAULT_TABLESPACE self.meta = meta self.pk = None self.has_auto_field = False self.auto_field = None self.abstract = False self.managed = True self.proxy = False # For any class that is a proxy (including automatically created # classes for deferred object loading), proxy_for_model tells us # which class this model is proxying. Note that proxy_for_model # can create a chain of proxy models. For non-proxy models, the # variable is always None. self.proxy_for_model = None # For any non-abstract class, the concrete class is the model # in the end of the proxy_for_model chain. In particular, for # concrete models, the concrete_model is always the class itself. self.concrete_model = None self.swappable = None self.parents = OrderedDict() self.auto_created = False # To handle various inheritance situations, we need to track where # managers came from (concrete or abstract base classes). `managers` # keeps a list of 3-tuples of the form: # (creation_counter, instance, abstract(=True)) self.managers = [] # List of all lookups defined in ForeignKey 'limit_choices_to' options # from *other* models. Needed for some admin checks. Internal use only. self.related_fkey_lookups = [] # A custom app registry to use, if you're making a separate model set. self.apps = apps self.default_related_name = None @lru_cache(maxsize=None) def _map_model(self, link): # This helper function is used to allow backwards compatibility with # the previous API. No future methods should use this function. # It maps a field to (field, model or related_model,) depending on the # field type. model = link.model._meta.concrete_model if model is self.model: model = None return link, model @lru_cache(maxsize=None) def _map_model_details(self, link): # This helper function is used to allow backwards compatibility with # the previous API. No future methods should use this function. # This function maps a field to a tuple of: # (field, model or related_model, direct, is_m2m) depending on the # field type. direct = not link.auto_created or link.concrete model = link.model._meta.concrete_model if model is self.model: model = None m2m = link.is_relation and link.many_to_many return link, model, direct, m2m @property def app_config(self): # Don't go through get_app_config to avoid triggering imports. return self.apps.app_configs.get(self.app_label) @property def installed(self): return self.app_config is not None @property def abstract_managers(self): return [ (counter, instance.name, instance) for counter, instance, abstract in self.managers if abstract ] @property def concrete_managers(self): return [ (counter, instance.name, instance) for counter, instance, abstract in self.managers if not abstract ] def contribute_to_class(self, cls, name): from django.db import connection from django.db.backends.utils import truncate_name cls._meta = self self.model = cls # First, construct the default values for these options. self.object_name = cls.__name__ self.model_name = self.object_name.lower() self.verbose_name = camel_case_to_spaces(self.object_name) # Store the original user-defined values for each option, # for use when serializing the model definition self.original_attrs = {} # Next, apply any overridden values from 'class Meta'. if self.meta: meta_attrs = self.meta.__dict__.copy() for name in self.meta.__dict__: # Ignore any private attributes that Django doesn't care about. # NOTE: We can't modify a dictionary's contents while looping # over it, so we loop over the *original* dictionary instead. if name.startswith('_'): del meta_attrs[name] for attr_name in DEFAULT_NAMES: if attr_name in meta_attrs: setattr(self, attr_name, meta_attrs.pop(attr_name)) self.original_attrs[attr_name] = getattr(self, attr_name) elif hasattr(self.meta, attr_name): setattr(self, attr_name, getattr(self.meta, attr_name)) self.original_attrs[attr_name] = getattr(self, attr_name) ut = meta_attrs.pop('unique_together', self.unique_together) self.unique_together = normalize_together(ut) it = meta_attrs.pop('index_together', self.index_together) self.index_together = normalize_together(it) # verbose_name_plural is a special case because it uses a 's' # by default. if self.verbose_name_plural is None: self.verbose_name_plural = string_concat(self.verbose_name, 's') # Any leftover attributes must be invalid. if meta_attrs != {}: raise TypeError("'class Meta' got invalid attribute(s): %s" % ','.join(meta_attrs.keys())) else: self.verbose_name_plural = string_concat(self.verbose_name, 's') del self.meta # If the db_table wasn't provided, use the app_label + model_name. if not self.db_table: self.db_table = "%s_%s" % (self.app_label, self.model_name) self.db_table = truncate_name(self.db_table, connection.ops.max_name_length()) def _prepare(self, model): if self.order_with_respect_to: # The app registry will not be ready at this point, so we cannot # use get_field(). query = self.order_with_respect_to try: self.order_with_respect_to = next( f for f in self._get_fields(reverse=False) if f.name == query or f.attname == query ) except StopIteration: raise FieldDoesNotExist('%s has no field named %r' % (self.object_name, query)) self.ordering = ('_order',) if not any(isinstance(field, OrderWrt) for field in model._meta.local_fields): model.add_to_class('_order', OrderWrt()) else: self.order_with_respect_to = None if self.pk is None: if self.parents: # Promote the first parent link in lieu of adding yet another # field. field = next(six.itervalues(self.parents)) # Look for a local field with the same name as the # first parent link. If a local field has already been # created, use it instead of promoting the parent already_created = [fld for fld in self.local_fields if fld.name == field.name] if already_created: field = already_created[0] field.primary_key = True self.setup_pk(field) else: auto = AutoField(verbose_name='ID', primary_key=True, auto_created=True) model.add_to_class('id', auto) def add_field(self, field, virtual=False): # Insert the given field in the order in which it was created, using # the "creation_counter" attribute of the field. # Move many-to-many related fields from self.fields into # self.many_to_many. if virtual: self.virtual_fields.append(field) elif field.is_relation and field.many_to_many: self.local_many_to_many.insert(bisect(self.local_many_to_many, field), field) else: self.local_fields.insert(bisect(self.local_fields, field), field) self.setup_pk(field) # If the field being added is a relation to another known field, # expire the cache on this field and the forward cache on the field # being referenced, because there will be new relationships in the # cache. Otherwise, expire the cache of references *to* this field. # The mechanism for getting at the related model is slightly odd - # ideally, we'd just ask for field.related_model. However, related_model # is a cached property, and all the models haven't been loaded yet, so # we need to make sure we don't cache a string reference. if field.is_relation and hasattr(field.rel, 'to') and field.rel.to: try: field.rel.to._meta._expire_cache(forward=False) except AttributeError: pass self._expire_cache() else: self._expire_cache(reverse=False) def setup_pk(self, field): if not self.pk and field.primary_key: self.pk = field field.serialize = False def setup_proxy(self, target): """ Does the internal setup so that the current model is a proxy for "target". """ self.pk = target._meta.pk self.proxy_for_model = target self.db_table = target._meta.db_table def __repr__(self): return '<Options for %s>' % self.object_name def __str__(self): return "%s.%s" % (smart_text(self.app_label), smart_text(self.model_name)) @property def verbose_name_raw(self): """ There are a few places where the untranslated verbose name is needed (so that we get the same value regardless of currently active locale). """ with override(None): return force_text(self.verbose_name) @property def swapped(self): """ Has this model been swapped out for another? If so, return the model name of the replacement; otherwise, return None. For historical reasons, model name lookups using get_model() are case insensitive, so we make sure we are case insensitive here. """ if self.swappable: model_label = '%s.%s' % (self.app_label, self.model_name) swapped_for = getattr(settings, self.swappable, None) if swapped_for: try: swapped_label, swapped_object = swapped_for.split('.') except ValueError: # setting not in the format app_label.model_name # raising ImproperlyConfigured here causes problems with # test cleanup code - instead it is raised in get_user_model # or as part of validation. return swapped_for if '%s.%s' % (swapped_label, swapped_object.lower()) not in (None, model_label): return swapped_for return None @cached_property def fields(self): """ Returns a list of all forward fields on the model and its parents, excluding ManyToManyFields. Private API intended only to be used by Django itself; get_fields() combined with filtering of field properties is the public API for obtaining this field list. """ # For legacy reasons, the fields property should only contain forward # fields that are not virtual or with a m2m cardinality. Therefore we # pass these three filters as filters to the generator. # The third lambda is a longwinded way of checking f.related_model - we don't # use that property directly because related_model is a cached property, # and all the models may not have been loaded yet; we don't want to cache # the string reference to the related_model. is_not_an_m2m_field = lambda f: not (f.is_relation and f.many_to_many) is_not_a_generic_relation = lambda f: not (f.is_relation and f.one_to_many) is_not_a_generic_foreign_key = lambda f: not ( f.is_relation and f.many_to_one and not (hasattr(f.rel, 'to') and f.rel.to) ) return make_immutable_fields_list( "fields", (f for f in self._get_fields(reverse=False) if is_not_an_m2m_field(f) and is_not_a_generic_relation(f) and is_not_a_generic_foreign_key(f)) ) @cached_property def concrete_fields(self): """ Returns a list of all concrete fields on the model and its parents. Private API intended only to be used by Django itself; get_fields() combined with filtering of field properties is the public API for obtaining this field list. """ return make_immutable_fields_list( "concrete_fields", (f for f in self.fields if f.concrete) ) @cached_property def local_concrete_fields(self): """ Returns a list of all concrete fields on the model. Private API intended only to be used by Django itself; get_fields() combined with filtering of field properties is the public API for obtaining this field list. """ return make_immutable_fields_list( "local_concrete_fields", (f for f in self.local_fields if f.concrete) ) @raise_deprecation(suggested_alternative="get_fields()") def get_fields_with_model(self): return [self._map_model(f) for f in self.get_fields()] @raise_deprecation(suggested_alternative="get_fields()") def get_concrete_fields_with_model(self): return [self._map_model(f) for f in self.concrete_fields] @cached_property def many_to_many(self): """ Returns a list of all many to many fields on the model and its parents. Private API intended only to be used by Django itself; get_fields() combined with filtering of field properties is the public API for obtaining this list. """ return make_immutable_fields_list( "many_to_many", (f for f in self._get_fields(reverse=False) if f.is_relation and f.many_to_many) ) @cached_property def related_objects(self): """ Returns all related objects pointing to the current model. The related objects can come from a one-to-one, one-to-many, or many-to-many field relation type. Private API intended only to be used by Django itself; get_fields() combined with filtering of field properties is the public API for obtaining this field list. """ all_related_fields = self._get_fields(forward=False, reverse=True, include_hidden=True) return make_immutable_fields_list( "related_objects", (obj for obj in all_related_fields if not obj.hidden or obj.field.many_to_many) ) @raise_deprecation(suggested_alternative="get_fields()") def get_m2m_with_model(self): return [self._map_model(f) for f in self.many_to_many] @cached_property def _forward_fields_map(self): res = {} fields = self._get_fields(reverse=False) for field in fields: res[field.name] = field # Due to the way Django's internals work, get_field() should also # be able to fetch a field by attname. In the case of a concrete # field with relation, includes the *_id name too try: res[field.attname] = field except AttributeError: pass return res @cached_property def fields_map(self): res = {} fields = self._get_fields(forward=False, include_hidden=True) for field in fields: res[field.name] = field # Due to the way Django's internals work, get_field() should also # be able to fetch a field by attname. In the case of a concrete # field with relation, includes the *_id name too try: res[field.attname] = field except AttributeError: pass return res
[docs] def get_field(self, field_name, many_to_many=None): """ Returns a field instance given a field name. The field can be either a forward or reverse field, unless many_to_many is specified; if it is, only forward fields will be returned. The many_to_many argument exists for backwards compatibility reasons; it has been deprecated and will be removed in Django 1.10. """ m2m_in_kwargs = many_to_many is not None if m2m_in_kwargs: # Always throw a warning if many_to_many is used regardless of # whether it alters the return type or not. warnings.warn( "The 'many_to_many' argument on get_field() is deprecated; " "use a filter on field.many_to_many instead.", RemovedInDjango110Warning ) try: # In order to avoid premature loading of the relation tree # (expensive) we prefer checking if the field is a forward field. field = self._forward_fields_map[field_name] if many_to_many is False and field.many_to_many: raise FieldDoesNotExist( '%s has no field named %r' % (self.object_name, field_name) ) return field except KeyError: # If the app registry is not ready, reverse fields are # unavailable, therefore we throw a FieldDoesNotExist exception. if not self.apps.models_ready: raise FieldDoesNotExist( "%s has no field named %r. The app cache isn't ready yet, " "so if this is an auto-created related field, it won't " "be available yet." % (self.object_name, field_name) ) try: if m2m_in_kwargs: # Previous API does not allow searching reverse fields. raise FieldDoesNotExist('%s has no field named %r' % (self.object_name, field_name)) # Retrieve field instance by name from cached or just-computed # field map. return self.fields_map[field_name] except KeyError:
raise FieldDoesNotExist('%s has no field named %r' % (self.object_name, field_name)) @raise_deprecation(suggested_alternative="get_field()") def get_field_by_name(self, name): return self._map_model_details(self.get_field(name)) @raise_deprecation(suggested_alternative="get_fields()") def get_all_field_names(self): names = set() fields = self.get_fields() for field in fields: # For backwards compatibility GenericForeignKey should not be # included in the results. if field.is_relation and field.many_to_one and field.related_model is None: continue # Relations to child proxy models should not be included. if (field.model != self.model and field.model._meta.concrete_model == self.concrete_model): continue names.add(field.name) if hasattr(field, 'attname'): names.add(field.attname) return list(names) @raise_deprecation(suggested_alternative="get_fields()") def get_all_related_objects(self, local_only=False, include_hidden=False, include_proxy_eq=False): include_parents = True if local_only is False else PROXY_PARENTS fields = self._get_fields( forward=False, reverse=True, include_parents=include_parents, include_hidden=include_hidden, ) fields = (obj for obj in fields if not isinstance(obj.field, ManyToManyField)) if include_proxy_eq: children = chain.from_iterable(c._relation_tree for c in self.concrete_model._meta.proxied_children if c is not self) relations = (f.rel for f in children if include_hidden or not f.rel.field.rel.is_hidden()) fields = chain(fields, relations) return list(fields) @raise_deprecation(suggested_alternative="get_fields()") def get_all_related_objects_with_model(self, local_only=False, include_hidden=False, include_proxy_eq=False): return [ self._map_model(f) for f in self.get_all_related_objects( local_only=local_only, include_hidden=include_hidden, include_proxy_eq=include_proxy_eq, ) ] @raise_deprecation(suggested_alternative="get_fields()") def get_all_related_many_to_many_objects(self, local_only=False): include_parents = True if local_only is not True else PROXY_PARENTS fields = self._get_fields( forward=False, reverse=True, include_parents=include_parents, include_hidden=True ) return [obj for obj in fields if isinstance(obj.field, ManyToManyField)] @raise_deprecation(suggested_alternative="get_fields()") def get_all_related_m2m_objects_with_model(self): fields = self._get_fields(forward=False, reverse=True, include_hidden=True) return [self._map_model(obj) for obj in fields if isinstance(obj.field, ManyToManyField)] def get_base_chain(self, model): """ Returns a list of parent classes leading to 'model' (order from closet to most distant ancestor). This has to handle the case were 'model' is a grandparent or even more distant relation. """ if not self.parents: return None if model in self.parents: return [model] for parent in self.parents: res = parent._meta.get_base_chain(model) if res: res.insert(0, parent) return res return None def get_parent_list(self): """ Returns all the ancestors of this model as a list ordered by MRO. Useful for determining if something is an ancestor, regardless of lineage. """ result = OrderedSet(self.parents) for parent in self.parents: for ancestor in parent._meta.get_parent_list(): result.add(ancestor) return list(result) def get_ancestor_link(self, ancestor): """ Returns the field on the current model which points to the given "ancestor". This is possible an indirect link (a pointer to a parent model, which points, eventually, to the ancestor). Used when constructing table joins for model inheritance. Returns None if the model isn't an ancestor of this one. """ if ancestor in self.parents: return self.parents[ancestor] for parent in self.parents: # Tries to get a link field from the immediate parent parent_link = parent._meta.get_ancestor_link(ancestor) if parent_link: # In case of a proxied model, the first link # of the chain to the ancestor is that parent # links return self.parents[parent] or parent_link def _populate_directed_relation_graph(self): """ This method is used by each model to find its reverse objects. As this method is very expensive and is accessed frequently (it looks up every field in a model, in every app), it is computed on first access and then is set as a property on every model. """ related_objects_graph = defaultdict(list) all_models = self.apps.get_models(include_auto_created=True) for model in all_models: # Abstract model's fields are copied to child models, hence we will # see the fields from the child models. if model._meta.abstract: continue fields_with_relations = ( f for f in model._meta._get_fields(reverse=False, include_parents=False) if f.is_relation and f.related_model is not None ) for f in fields_with_relations: if not isinstance(f.rel.to, six.string_types): related_objects_graph[f.rel.to._meta].append(f) for model in all_models: # Set the relation_tree using the internal __dict__. In this way # we avoid calling the cached property. In attribute lookup, # __dict__ takes precedence over a data descriptor (such as # @cached_property). This means that the _meta._relation_tree is # only called if related_objects is not in __dict__. related_objects = related_objects_graph[model._meta] model._meta.__dict__['_relation_tree'] = related_objects # It seems it is possible that self is not in all_models, so guard # against that with default for get(). return self.__dict__.get('_relation_tree', EMPTY_RELATION_TREE) @cached_property def _relation_tree(self): return self._populate_directed_relation_graph() def _expire_cache(self, forward=True, reverse=True): # This method is usually called by apps.cache_clear(), when the # registry is finalized, or when a new field is added. properties_to_expire = [] if forward: properties_to_expire.extend(self.FORWARD_PROPERTIES) if reverse and not self.abstract: properties_to_expire.extend(self.REVERSE_PROPERTIES) for cache_key in properties_to_expire: try: delattr(self, cache_key) except AttributeError: pass self._get_fields_cache = {}
[docs] def get_fields(self, include_parents=True, include_hidden=False): """ Returns a list of fields associated to the model. By default, includes forward and reverse fields, fields derived from inheritance, but not hidden fields. The returned fields can be changed using the parameters: - include_parents: include fields derived from inheritance - include_hidden: include fields that have a related_name that starts with a "+" """ if include_parents is False: include_parents = PROXY_PARENTS
return self._get_fields(include_parents=include_parents, include_hidden=include_hidden) def _get_fields(self, forward=True, reverse=True, include_parents=True, include_hidden=False, seen_models=None): """ Internal helper function to return fields of the model. * If forward=True, then fields defined on this model are returned. * If reverse=True, then relations pointing to this model are returned. * If include_hidden=True, then fields with is_hidden=True are returned. * The include_parents argument toggles if fields from parent models should be included. It has three values: True, False, and PROXY_PARENTS. When set to PROXY_PARENTS, the call will return all fields defined for the current model or any of its parents in the parent chain to the model's concrete model. """ if include_parents not in (True, False, PROXY_PARENTS): raise TypeError("Invalid argument for include_parents: %s" % (include_parents,)) # This helper function is used to allow recursion in ``get_fields()`` # implementation and to provide a fast way for Django's internals to # access specific subsets of fields. # We must keep track of which models we have already seen. Otherwise we # could include the same field multiple times from different models. topmost_call = False if seen_models is None: seen_models = set() topmost_call = True seen_models.add(self.model) # Creates a cache key composed of all arguments cache_key = (forward, reverse, include_parents, include_hidden, topmost_call) try: # In order to avoid list manipulation. Always return a shallow copy # of the results. return self._get_fields_cache[cache_key] except KeyError: pass fields = [] # Recursively call _get_fields() on each parent, with the same # options provided in this call. if include_parents is not False: for parent in self.parents: # In diamond inheritance it is possible that we see the same # model from two different routes. In that case, avoid adding # fields from the same parent again. if parent in seen_models: continue if (parent._meta.concrete_model != self.concrete_model and include_parents == PROXY_PARENTS): continue for obj in parent._meta._get_fields( forward=forward, reverse=reverse, include_parents=include_parents, include_hidden=include_hidden, seen_models=seen_models): if hasattr(obj, 'parent_link') and obj.parent_link: continue fields.append(obj) if reverse: # Tree is computed once and cached until the app cache is expired. # It is composed of a list of fields pointing to the current model # from other models. all_fields = self._relation_tree for field in all_fields: # If hidden fields should be included or the relation is not # intentionally hidden, add to the fields dict. if include_hidden or not field.rel.hidden: fields.append(field.rel) if forward: fields.extend( field for field in chain(self.local_fields, self.local_many_to_many) ) # Virtual fields are recopied to each child model, and they get a # different model as field.model in each child. Hence we have to # add the virtual fields separately from the topmost call. If we # did this recursively similar to local_fields, we would get field # instances with field.model != self.model. if topmost_call: fields.extend( f for f in self.virtual_fields ) # In order to avoid list manipulation. Always # return a shallow copy of the results fields = make_immutable_fields_list("get_fields()", fields) # Store result into cache for later access self._get_fields_cache[cache_key] = fields
return fields
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