/// note | Technical Details

You could also use `from starlette.websockets import WebSocket`.

**FastAPI** provides the same `WebSocket` directly just as a convenience for you, the developer. But it comes directly from Starlette.

///

## Await for messages and send messages { #await-for-messages-and-send-messages }

In your WebSocket route you can `await` for messages and send messages.

///

### Avoid name collisions { #avoid-name-collisions }

We are importing the submodule `items` directly, instead of importing just its variable `router`.

This is because we also have another variable named `router` in the submodule `users`.

If we had imported one after the other, like:

```Python

import org.jspecify.annotations.Nullable;
import org.junit.Ignore;

/** Skeleton for a tester of a {@code BiMap}. */
@GwtCompatible
@Ignore("test runners must not instantiate and run this directly, only via suites we build")
// @Ignore affects the Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.
@SuppressWarnings("JUnit4ClassUsedInJUnit3")
@NullMarked

Each section gradually builds on the previous ones, but it's structured to separate topics, so that you can go directly to any specific one to solve your specific API needs.

It is also built to work as a future reference so you can come back and see exactly what you need.

## Run the code { #run-the-code }

All the code blocks can be copied and used directly (they are actually tested Python files).

# `FastAPI` class

Here's the reference information for the `FastAPI` class, with all its parameters, attributes and methods.

You can import the `FastAPI` class directly from `fastapi`:

```python
from fastapi import FastAPI
```

::: fastapi.FastAPI
    options:
        members:
            - openapi_version
            - webhooks
            - state
            - dependency_overrides
            - openapi

This also means that in many cases you can pass the same object you get from a request **directly to the database**, as everything is validated automatically.

The same applies the other way around, in many cases you can just pass the object you get from the database **directly to the client**.

With **FastAPI** you get all of **Pydantic**'s features (as FastAPI is based on Pydantic for all the data handling):

///

/// warning

Have in mind that the `RequestValidationError` contains the information of the file name and line where the validation error happens so that you can show it in your logs with the relevant information if you want to.

       * properly.
       */
      /*
       * This reference is part of a reference cycle, which is typically something we want to avoid
       * under j2objc -- but it is not detected by our j2objc cycle test. The cycle:
       *
       * - CustomScheduler.service contains an instance of ServiceDelegate. (It needs it so that it
       *   can call notifyFailed.)
       *

          return of(onlyEntry.getKey(), onlyEntry.getValue());
        default:
          /*
           * If entries is full, or if hash flooding is detected, then this implementation may end
           * up using the entries array directly and writing over the entry objects with
           * non-terminal entries, but this is safe; if this Builder is used further, it will grow

import com.google.errorprone.annotations.Immutable;

/**
 * Explicitly named subinterface of {@link Supplier} that can be marked {@literal @}{@link
 * Immutable}.
 */
// TODO(cpovirk): Should we just use ChecksumType directly instead of defining this type?
@Immutable