How can I access custom blocks using Block.load(<slug>/<name>)?

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I have defined a new custom block to connect to MongoDB as follows:

class MongoDBConnection(Block):
    host: str
    username: str
    password: SecretStr
    authSource: Optional[str] = 'admin'

    def get_client(self) -> MongoClient:
        return MongoClient(
            host=self.host,
            username=self.username,
            password=self.password.get_secret_value(),
            authSource=self.authSource
        )

I have registered the block using the cli as follows:

prefect block register --file mongodb_connection.py

I have no issues using this block if I import the class from mongodb_connection.py and call MongoDBConnection.load(<name>). However, I would like to use the generic Block.load(<slug>/<name>) pattern to avoid messy imports when sharing custom block definitions between flows.

I get the following error when I try to use the generic load pattern:

>>> mongo_block = Block.load('mongodbconnection/<name>')

KeyError: "No class found for dispatch key 'mongodbconnection' in registry for type 'Block'."

How would I go about using my custom blocks without needing messy imports?

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2

one option would be to install it as a package in your execution environment, as shown in the repo:

unfortunately, the flow code/module still must be installed within the environment, the block only stores the configuration data and methods server side, the code remains private on your infrastructure for privacy reasons

3

Fantastic, thank you! This is the solution I ended up using and it is very clean and simple.

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