labthings_fastapi.dependencies.thing_server

Retrieve the ThingServer object.

This module provides a function that will retrieve the ThingServer based on the fastapi.Request object. It may be used as a dependency with Annotated[ThingServer, Depends(thing_server_from_request)].

See Dependencies for more information on the dependency mechanism, and Using Things from other Things for more on how Things interact.

Note

This module does not provide a ready-made annotated type to use as a dependency. Doing so would mean this module has a hard dependency on ThingServer and cause circular references. See above for the annotated type, which you may define in any code that needs it.

Note

The rationale for this function is that we want to make sure Thing instances only access the server associated with the current request. This means that we use the fastapi.Request to look up the fastapi.FastAPI app, and then use the app to look up the ThingServer.

As each Thing is connected to exactly one ThingServer, this may become unnecessary in the future as the server could be exposed as a property of the Thing.

Attributes

_thing_servers

Functions

find_thing_server(→ labthings_fastapi.server.ThingServer)	Find the ThingServer associated with an app.
thing_server_from_request(...)	Retrieve the ThingServer from a request.

Module Contents

labthings_fastapi.dependencies.thing_server._thing_servers: weakref.WeakSet[labthings_fastapi.server.ThingServer]

labthings_fastapi.dependencies.thing_server.find_thing_server(app: fastapi.FastAPI) → labthings_fastapi.server.ThingServer

Find the ThingServer associated with an app.

This function will return the ThingServer object that contains a particular fastapi.FastAPI app. The app is available as part of the fastapi.Request object, so this makes it possible to get the ThingServer in dependency functions.

This function will not work as a dependency, but thing_server_from_request will.

Parameters:

app – The fastapi.FastAPI application that implements the ThingServer, i.e. this is thing_server.app.

Returns:

the ThingServer that owns the app.

Raises:

RuntimeError – if there is no ThingServer associated with the current FastAPI application. This should only happen if this function is called on a fastapi.FastAPI instance that was not created by a ThingServer.

labthings_fastapi.dependencies.thing_server.thing_server_from_request(request: fastapi.Request) → labthings_fastapi.server.ThingServer

Retrieve the ThingServer from a request.

This is for use as a FastAPI dependency, so the thing server is retrieved from the request object. See find_thing_server.

It may be used as a dependency with:

ServerDep = Annotated[ThingServer, Depends(thing_server_from_request)]

This is not provided as a ready-made annotated type because it would introduce a hard dependency on the server module and cause circular references.

Parameters:

request – is supplied automatically by FastAPI when used as a dependency.

Returns:

the ThingServer handling the current request.