Context Registry

The context registry maps template codes to the models and variables available when rendering that template. This powers both the Model Inspector in the UI and the dummy context generation for template previews.

Registering a Context

Register contexts in your app’s AppConfig.ready() or a module imported at startup:

from djgentelella.async_notification.registry import register_context

register_context(
    code='order_confirmation',
    subject='Order #{{ order.id }} Confirmed',
    models={
        'order': 'myapp.Order',
        'user': 'auth.User',
    },
    exclude={
        'user': ['password', 'last_login', 'is_superuser'],
    },
    extra_variables={
        'site_url': 'Full URL of the site',
        'support_email': 'Support team email address',
    },
    depth=2,
    preview_provider='myapp.previews.OrderPreviewProvider',
)

Parameters:

• code (str) - Unique identifier for this context. Used in the EmailTemplate.context_code field.

• subject (str) - Default subject template string.

• models (dict) - Maps variable prefixes to model strings in app_label.ModelName format.

• exclude (dict, optional) - Maps prefixes to lists of field names to exclude from introspection.

• extra_variables (dict, optional) - Maps variable names to human-readable descriptions. These are shown in the Model Inspector but are not tied to model fields.

• depth (int, default 2) - Maximum depth for following FK/O2O relations during introspection.

• preview_provider (str or class, optional) - Dotted path or class for generating real preview data.

Retrieving Contexts

from djgentelella.async_notification.registry import (
    get_context_config, get_all_contexts
)

# Get a single context
config = get_context_config('order_confirmation')
# Returns dict with: code, subject, models, exclude,
#                     extra_variables, depth, preview_provider

# Get all registered contexts
all_contexts = get_all_contexts()
# Returns dict mapping codes to their configurations

How the Registry is Used

In the management UI:

When a user selects a context_code in the email template editor, the UI fetches the model fields from the /model-fields/ endpoint, which calls get_fields_for_context() internally. This shows the user which template variables are available (e.g., {{ order.id }}, {{ user.email }}).

For template preview:

When previewing a template, build_dummy_context() uses the registry to generate type-appropriate dummy values for all model fields and extra variables.

In serializers:

When saving an EmailTemplate, the context_code is persisted so that later previews (including from the table listing) know which context to use.

Example: Full Registration

# myapp/apps.py
from django.apps import AppConfig

class MyAppConfig(AppConfig):
    name = 'myapp'

    def ready(self):
        from djgentelella.async_notification.registry import register_context

        register_context(
            code='user_welcome',
            subject='Welcome, {{ user.first_name }}!',
            models={'user': 'auth.User'},
            exclude={'user': ['password', 'last_login', 'groups',
                              'user_permissions']},
            extra_variables={
                'login_url': 'URL to the login page',
                'site_name': 'Name of the site',
            },
        )

        register_context(
            code='password_reset',
            subject='Password Reset for {{ user.username }}',
            models={'user': 'auth.User'},
            exclude={'user': ['password']},
            extra_variables={
                'reset_url': 'Password reset link',
                'expiry_hours': 'Hours until the link expires',
            },
        )

Clearing the Registry

For testing purposes, the registry can be cleared:

from djgentelella.async_notification.registry import clear_registry

clear_registry()