MongoDB storage plugin

Quick guide

This is a quickguide for users wishing to connect to a mongodb server. It is assumed that they have access to a server and have their own username and password (or they have access to a connection string).

The MongoDB dlite plugin used the Python client pymongo.MongoClient to connect to the server. The main parameter to set-up a connection to a MongoDB database is the URI, many options like the user name and the password can be defined in the URI (see mongodb URI for more details).

First, set up the connection string:

>>> user = "USERNAME"
>>> password = "PASSWORD"
>>> server = "MYSERVERADDRESS"
>>> uri =  f"mongodb+srv://{user}:{password}@{server}"

Then, you must define the name of the database and the name of the collection. The dlite storage will store and retireve instances from a collection (see the definitions of Databases and Collections).

>>> database = "test-database"
>>> collection = "test-collection"

With those information you can create a dlite storage instance.

>>> import dlite
>>> options = f"mode=w,database={database},collection={collection}"
>>> storage = dlite.Storage("mongodb", uri, options)

This storage instance can then be used like any other dlite storage instance. For example saving and loading instances:

>>> inst1 = dlite.Instance.from_location("json", "MY/INSTANCE/PATH.JSON")
>>> storage.save(inst1)
>>> storage.load(inst1.uuid)

Replace “MY/INSTANCE/PATH.JSON” with the path to your instance file, and make sure to use the correct username, password, and server address for your MongoDB server.

Initialize the MongoClient with more options

All options/parameters of the MongoClient constructor can be passed via the dlite storage parameters options, like shown below.

>>> import dlite
>>> from dlite.options import Options
>>> options = Options(f"mode=w,database={database},collection={collection}")
>>> options.update(connect=False, maxPoolSize=200)
>>> storage = dlite.Storage("mongodb", uri, str(options))

Connect to Azure MongoDB

In the Azure portal, create an Azure CosmosDB for MongoDB account, then open the new account, and open the menu Settings > Connection strings. In the Connection strings page, show and copy to the clipboard the PRIMARY CONNECTION STRING. Then paste the string to a .env file.

# ".env" file
AZURE_MONGODB=mongodb://...

Then, in your Python code, load the connection string and use it to create a dlite storage.

>>> from dotenv import dotenv_values
>>> config = dotenv_values(".env")
>>> options = "mode=w,database=test-database,collection=test-collection"
>>> storage = dlite.Storage("mongodb", config["AZURE_MONGODB"], options)