Component

Component is an object shared in spangle app. It is useful to store database connections or global configurations.

Define your components

class MyComponent:
    # `__init__` must take no args except `self` .
    def __init__(self):
        self.value = 42

api.register_component(MyComponent)

Now, you are ready to use that component in your api .

Use components in view-classes

To use components in view classes, call use_component.

from spangle import use_component

@api.route("/comp")
class UseComponent:
    async def on_get(self, req, resp):
        my_comp = use_component(MyComponent)
        assert my_comp.value == 42

Note

According to The Twelve-FactorApp , every application process should be stateless. In other words, components should contain config or database connection, but not session data. Do not use a component as a datastore.

Use components from another component

A component can refer other components.

class AnotherComp:
    async def startup(self):
        # `async` is optional.
        my_comp = use_component(MyComponent)

Note

There is no way to define the order of startup hooks. Do not expect that startup hooks of other components are already completed.

Call use_component out of api context

If you want to use components out of api context(like test environment), you can set context by passing Api instance.

component = use_component(MyComponent, api=your_api)

Use Api instance as a component

You can use Api instance in view classes or components by calling use_api.

class Comp:
    def startup(self):
        api = use_api()