MongoBackend

MongoDB result backend.

Attributes

Attribute	Type	Description
mongo_host	list = null	A list of host strings or a single MongoDB connection URI used to establish the connection.
host	string = localhost	The hostname of the MongoDB server to connect to when mongo_host is not provided.
port	integer = 27017	The port number on which the MongoDB server is listening.
user	string = null	The username used for authenticating the connection to the MongoDB database.
password	string = null	The password used for authenticating the connection to the MongoDB database.
database_name	string = celery	The name of the MongoDB database where task and group metadata will be stored.
taskmeta_collection	string = celery_taskmeta	The name of the MongoDB collection used to store task state and results.
groupmeta_collection	string = celery_groupmeta	The name of the MongoDB collection used to store group result metadata.
max_pool_size	integer = 10	The maximum number of connections allowed in the MongoDB connection pool.
options	dict = null	A dictionary of additional configuration parameters passed directly to the MongoClient.
supports_autoexpire	boolean = false	Indicates whether the backend supports automatic expiration of records via MongoDB TTL indexes.

---

Constructor

Signature

def MongoBackend(
    app: [Celery](../../app/base/celery.md?sid=celery_app_base_celery) = None,
    kwargs: dict
) - > null

Parameters

Name	Type	Description
app	[Celery](../../app/base/celery.md?sid=celery_app_base_celery) = None	The Celery application instance.
kwargs	dict	Additional keyword arguments passed to the base backend.

---

Methods

---

encode()

@classmethod
def encode(
    data: any
) - > any

Serializes data for storage in MongoDB, wrapping binary data in BSON-compatible types if necessary.

Parameters

Name	Type	Description
data	any	The task result or metadata to be encoded.

Returns

Type	Description
any	The serialized data or a BSON Binary object suitable for MongoDB storage.

---

decode()

@classmethod
def decode(
    data: any
) - > any

Deserializes data retrieved from MongoDB back into its original Python representation.

Parameters

Name	Type	Description
data	any	The encoded data retrieved from the database.

Returns

Type	Description
any	The decoded task result or metadata.

---

task_result_exists()

@classmethod
def task_result_exists(
    task_id: string
) - > boolean

Check if a result exists in MongoDB for the given task ID.

Parameters

Name	Type	Description
task_id	string	The unique identifier of the task to check.

Returns

Type	Description
boolean	True if a record for the task ID exists, otherwise False.

---

cleanup()

@classmethod
def cleanup() - > null

Delete expired meta-data.

Returns

Type	Description
null	null

---

database()

@classmethod
def database() - > pymongo.database.Database

Get database from MongoDB connection.

Returns

Type	Description
pymongo.database.Database	The authenticated MongoDB database instance.

---

collection()

@classmethod
def collection() - > pymongo.collection.Collection

Get the meta-data task collection.

Returns

Type	Description
pymongo.collection.Collection	The MongoDB collection used for task metadata, with an index on date_done.

---

group_collection()

@classmethod
def group_collection() - > pymongo.collection.Collection

Get the meta-data task collection.

Returns

Type	Description
pymongo.collection.Collection	The MongoDB collection used for group metadata, with an index on date_done.

---

expires_delta()

@classmethod
def expires_delta() - > datetime.timedelta

Calculates the expiration time as a timedelta object based on the backend settings.

Returns

Type	Description
datetime.timedelta	The duration after which results should expire.

---

as_uri()

@classmethod
def as_uri(
    include_password: boolean
) - > string

Return the backend as an URI.

Parameters

Name	Type	Description
include_password	boolean	Whether to include the plain-text password in the returned URI.

Returns

Type	Description
string	The connection URI, optionally with the password sanitized.

---