Providers

Providers¶

Providers are a fundamental concept in Nest. Many of the basic Nest classes may be treated as a provider – services, repositories, factories, helpers, and so on. The main idea of a provider is that it can be injected as a dependency; this means objects can create various relationships with each other, and the function of "wiring up" these objects can largely be delegated to the Nest runtime system.

Services¶

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Dependency injection¶

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Scopes¶

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Custom providers¶

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Optional providers¶

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Property-based injection¶

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Provider registration¶

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Now that we have defined a provider (SnakesService), and we have a consumer of that service (SnakesController), we need to register the service with Nest so that it can perform the injection. We do this by editing our module file (snakes_module.py``) and adding the service to theprovidersarray of the@Module()` decorator.

Nest will now be able to resolve the dependencies of the SnakesController class.

snakes_module.py
from nest.common.decorators import Module

from snakes.snakes_controller import SnakesController 
from snakes.snakes_service import SnakesService

@Module(
    controllers=[SnakesController], # (1)
    providers=[SnakesService] # (2)
)
class SnakesModule: 
    pass

:man_raising_hand: I'm a code annotation! I can contain code, formatted text, images, ... basically anything that can be written in Markdown.
:man_raising_hand: I'm a code annotation! I can contain code, formatted text, images, ... basically anything that can be written in Markdown.

This is how our directory structure should look now:

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Manual instantiation¶

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