Config

Defining Config Values

The values in a config are defined by creating a class that inherits from the ConfigModel class. Define the available fields like you would a TypedDict:

from superdesk.core.config import ConfigModel

class MyConfig(ConfigModel):
    url: str
    username: str
    password: str

Loading Configs

Configs must be loaded before they can be used. If you attempt to access a value in a config before it has been loaded, a RuntimeError will be raised. You can load a config in the following 2 days:

This allows us to manually load configs on demand. This is used by resource systems, such as mongo, to load different config options based on a prefix, such as MONGO or CONTENTAPI_MONGO.

The following are examples on how to load a config:

from typing import Dict, Any

def test_custom_config():
    # Mock app config
    app_config: Dict[str, Any] = {
        "MY_URL": "localhost:5700",
        "MY_USERNAME": "monkey",
        "MY_PASSWORD": "bars",
    }

    # Using the class level method to create the instance for us
    config = MyConfig.create_from_dict(app_config, prefix="MY")

    # Loading an already constructed config instance
    config = MyConfig()
    config.load_from_dict(app_config, prefix="MY")

    # Get the instance, and assert it's values
    config = MyConfig.create_from_dict(app_config, prefix="MY")
    assert config.url == "localhost:5700"
    assert config.username = "monkey"
    assert config.password = "bars"

    # The following line would raise a pydantic.ValidationError
    # because not all of the required fields of the config
    # would be populated from the supplied app config
    MyConfig.create_from_dict({}, prefix="MY")

You can also load the config from the currently running app config:

from superdesk.core.app import get_current_async_app

def test_config_from_app():
    config = MyConfig.create_from_dict(
        get_current_async_app().wsgi.config,
        prefix="MY"
    )

Validation

Under the hood the ConfigModel uses Pydantic. This enables us to use it’s validation system to ensure the config values are correct. If the loading fails, a pydantic.Validation exception will be raised.:

def test_invalid_configs():
    app_config: Dict[str, Any] = {
        "MY_URL": "localhost:5700",
        "MY_USERNAME": 1234,
    }
    MyConfig.create_from_dict(app_config, prefix="MY")

The above will fail validation because MY_USERNAME is the incorrect data type, and MY_PASSWORD is missing from the supplied config.

Config Reference

class ConfigModel[source]

Base config class used for loading/reading config values

classmethod create_from_dict(config: Dict[str, Any], prefix: str | None = None, freeze: bool = True) → Self

Construct a new config instance, populating values from config

Parameters:

  • config – The config dictionary used to populate the new ConfigModal instance

  • prefix – Optional prefix to use when looking up field names in the supplied dictionary

  • freeze – If True, will freeze the config instance so values cannot be modified

Returns:

Returns the new ConfigModal instance

Raises:

TypeError – If config is not a dict

load_from_dict(config: Dict[str, Any], prefix: str | None = None, freeze: bool = True, additional: dict | None = None)

Reload config instance values, populating them from config

Parameters:

  • config – The config dictionary used to populate the new ConfigModal instance

  • prefix – Optional prefix to use when looking up field names in the supplied dictionary

  • freeze – If True, will freeze the config instance so values cannot be modified

  • additional – Optional additional dictionary to populate config values

This will load a brand-new instance of the config, applying values from config on top of the class’ default values. This means any custom changes made before calling this will be lost.

get_config_key(key: str, prefix: str | None = None) → str[source]

Get a config key with optional prefix

Parameters:

  • key – The config key to use

  • prefix – Optional prefix to use when looking up field names in the supplied dictionary

Returns:

Returns the key with optional prefix applied