NestedObjects

This class facilitates the discovery and organization of related database objects into a hierarchical structure. It tracks relationships between instances using an internal edge graph and provides mechanisms to handle protected or restricted dependencies during collection. The class primarily offers functionality to represent these discovered relationships as a nested list for visualization or processing.

Attributes

Attribute	Type	Description
edges	dict = {}	A mapping of source instances to lists of target instances representing the relationships discovered during collection.
protected	set = set()	A set of model instances that cannot be deleted due to ProtectedError or RestrictedError constraints encountered during collection.
model_objs	defaultdict = defaultdict(set)	A dictionary grouping all collected model instances by their respective model class.

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Constructor

Signature

def NestedObjects(
    *args: any,
    force_collection: boolean = True,
    **kwargs: any
) - > null

Parameters

Name	Type	Description
*args	any	Variable length argument list passed to the parent Collector class.
force_collection	boolean = True	Flag to determine if collection should be forced regardless of certain constraints.
**kwargs	any	Arbitrary keyword arguments passed to the parent Collector class.

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Methods

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add_edge()

@classmethod
def add_edge(
    source: object,
    target: object
) - > null

Registers a relationship between a source object and a target object within the internal dependency graph.

Parameters

Name	Type	Description
source	object	The parent object or origin of the relationship; use None for root-level objects.
target	object	The dependent object being linked to the source.

Returns

Type	Description
null

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collect()

@classmethod
def collect(
    objs: iterable,
    source: object,
    source_attr: string
) - > object

Traverses and gathers related objects while building an edge map of dependencies and tracking protected or restricted instances that cannot be deleted.

Parameters

Name	Type	Description
objs	iterable	A collection of model instances to begin the collection process from.
source	object	The parent instance that triggered the collection of the current objects.
source_attr	string	The attribute name or string template representing the relationship from the source to the objects.

Returns

Type	Description
object	The result of the parent collector's collection process, typically representing the set of objects identified for deletion.

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related_objects()

@classmethod
def related_objects(
    related_model: [Model](../../../db/models/base/model.md?sid=django_db_models_base_model),
    related_fields: list,
    objs: iterable
) - > [QuerySet](../../../db/models/query/queryset.md?sid=django_db_models_query_queryset)

Fetches a QuerySet of related objects for the given model and fields, optimized with select_related to reduce database hits during traversal.

Parameters

Name	Type	Description
related_model	[Model](../../../db/models/base/model.md?sid=django_db_models_base_model)	The Django model class to query for related instances.
related_fields	list	A list of field objects used to define the relationship and optimize the query via select_related.
objs	iterable	The base objects for which related instances are being discovered.

Returns

Type	Description
[QuerySet](../../../db/models/query/queryset.md?sid=django_db_models_query_queryset)	A Django QuerySet containing the related objects with their foreign key relationships pre-fetched.

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nested()

@classmethod
def nested(
    format_callback: callable
) - > list

Return the graph as a nested list.

Parameters

Name	Type	Description
format_callback	callable	An optional function to format each object in the resulting list, such as returning its verbose name.

Returns

Type	Description
list	A hierarchical list structure representing the tree of collected objects and their dependencies.

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