Python models.ForeignKey方法代碼示例

# 需要導入模塊: from django.contrib.gis.db import models [as 別名]
# 或者: from django.contrib.gis.db.models import ForeignKey [as 別名]
def create_related_fields(self):
        """
            Create ForeignKey and ManyFields for each self.configuration.related_fields
        :return:
        """
        return map_dict_to_dict(
            lambda field_name, related_field_configuration: self.create_related_field(
                field_name,
                related_field_configuration),
            self.configuration.related_fields or {}) 

# 需要導入模塊: from django.contrib.gis.db import models [as 別名]
# 或者: from django.contrib.gis.db.models import ForeignKey [as 別名]
def dynamic_join_model_class(self, join_models, related_field_names):
        """
            Creates an unmanaged subclass of the feature class with extra fields to represent the
            the fields of the join_models. This also adds fields for any fields specified in the
            related_model_lookup. This is not for join models but ForeignKeys such as BuiltForm
            These latter fields must be specified explicitly because the main model and join models
            can't populate their foreign keys from the query because the query has to be
            a ValuesQuerySet in order to do the join. So we create id versions of the fields here
            (e.g. built_form_id) which the query can fill and then use that to manually
            set the foreign key reference in the Tastypie resource.
            :param join_models: Other feature models whose attributes should be added to the subclass
            :param related_field_names: List of field names of foreign key id fields (AutoFields)

        """
        main_model_class = self.dynamic_model_class()
        manager = main_model_class.objects
        # Exclude the following field types. Since the base Feature defines an id we'll still get that, which we want
        exclude_field_types = (ForeignKey, ToManyField, OneToOneField, GeometryField)
        all_field_paths_to_fields = merge(
            # Create fields to represented foreign key id fields
            # Our query fetches these ids since it can't fetch related objects (since its a values() query)
            map_to_dict(
                lambda field_name: [field_name.replace('__', '_x_'),
                                    IntegerField(field_name.replace('__', '_x_'), null=True)],
                related_field_names
            ),
            # The join fields for each joined related model
            *map(
                lambda related_model: related_field_paths_to_fields(
                    manager,
                    related_model,
                    exclude_field_types=exclude_field_types,
                    fields=limited_api_fields(related_model),
                    separator='_x_'),
                join_models)
        )

        abstract_feature_class = resolve_module_attr(self.configuration.abstract_class_name)
        # Make sure the class name is unique to the related models and the given ConfigEntity
        related_models_unique_id = '_'.join(sorted(map(lambda related_model: related_model.__name__, join_models), ))
        dynamic_model_clazz = dynamic_model_class(
            main_model_class,
            self.db_entity.schema,
            self.db_entity.table,
            class_name="{0}{1}{2}{3}Join".format(
                abstract_feature_class.__name__,
                self.db_entity.id,
                self.config_entity.id,
                related_models_unique_id),
            fields=all_field_paths_to_fields,
            class_attrs=self.configuration.class_attrs or {},
            related_class_lookup=self.configuration.related_class_lookup or {},
            is_managed=False,
            cacheable=False)
        logger.info("Created dynamic join model class %s" % dynamic_model_clazz)
        logger.debug("Created with model fields %s" % map(lambda field: field.name, dynamic_model_clazz._meta.fields))
        logger.debug("Created with related and join fields %s" % all_field_paths_to_fields)
        return dynamic_model_clazz 

# 需要導入模塊: from django.contrib.gis.db import models [as 別名]
# 或者: from django.contrib.gis.db.models import ForeignKey [as 別名]
def create_related_field(self, field_name, related_field_configuration):
        """
            Creates a ForeignKey or ManyToMany field based on related_field_configuration
        :param field_name:
        :param related_field_configuration: A dict containing related_key or related_class_name
            related_key: the instance of the sibling key of the config_entity whose dynamic_model_class is the relation type.
                For DbEntity/Features this would be the db_entity_key and the dynamic_model_class would be its FeatureClass
                For AnalysisModule this would be the analysis module key and its dynamic class
            related_class_name: rather than related_key, any model class, such as BuiltForm, to relate to.
            single: if True this is a ForeignKey (toOne) relationship. Otherwise a ManyToMany is created
        :return: A two-item tuple. First item is the field name and the second is the field.
        """

        config_entity = ConfigEntity._subclassed_by_id(self.configuration.scope)

        # TODO temp coverage of a key name name change
        related_field_configuration['related_key'] = related_field_configuration.get('related_key', related_field_configuration.get('related_db_entity_key'))

        if related_field_configuration.get('related_key', False):
            # field name matches name of peer self.db_entity_key--get it's feature class name
            related_db_entity = get_single_value_or_none(config_entity.computed_db_entities(key=related_field_configuration['related_key']))
            # Always call with no_ensure=True since the config_entity is the same. Otherwise we'd get infinite recursion
            related_class_name_or_model = self.__class__(self.config_entity, related_db_entity, no_ensure=True).dynamic_model_class()
        elif related_field_configuration.get('related_class_name', None):
            # A model class such as BuiltForm
            related_class_name_or_model = resolve_module_attr(related_field_configuration['related_class_name'])
        else:
            raise Exception("No related_key or related_class_name found on feature_class_configuration for self.configuration.key %s" % self.configuration.key)

        logger.info('Creating %r related field for %s using %s', related_field_configuration.get('single', None) and 'single' or 'm2m',
                    field_name, related_field_configuration)
        if related_field_configuration.get('single', None):
            return [field_name,
                    models.ForeignKey(related_class_name_or_model, null=True)]
        else:
            return [field_name,
                    models.ManyToManyField(related_class_name_or_model,
                                           # Pass a custom, readable table name for the through class for ManyToMany relations
                                           db_table='"{schema}"."{table}_{field_name}"'.format(
                                               schema=config_entity.schema(),
                                               table=self.configuration.key,
                                               field_name=field_name))]