# Dependencies { #dependencies }

**FastAPI** has a very powerful but intuitive **<dfn title="also known as components, resources, providers, services, injectables">Dependency Injection</dfn>** system.

It is designed to be very simple to use, and to make it very easy for any developer to integrate other components with **FastAPI**.

## What is "Dependency Injection" { #what-is-dependency-injection }

  So she was considering in her own mind (as well as she could,
for the hot day made her feel very sleepy and stupid), whether
the pleasure of making a daisy-chain would be worth the trouble
of getting up and picking the daisies, when suddenly a White
Rabbit with pink eyes ran close by her.

  There was nothing so VERY remarkable in that; nor did Alice
think it so VERY much out of the way to hear the Rabbit say to

    response = client.put(
        "/items/5",
        json={"description": "A very nice Item"},
    )
    assert response.status_code == 422, response.text
    assert response.json() == {
        "detail": [
            {
                "loc": ["body", "name"],
                "input": {"description": "A very nice Item"},
                "msg": "Field required",
                "type": "missing",

    response = client.put(
        "/items/5",
        json={"description": "A very nice Item"},
    )
    assert response.status_code == 422, response.text
    assert response.json() == {
        "detail": [
            {
                "loc": ["body", "name"],
                "input": {"description": "A very nice Item"},
                "msg": "Field required",
                "type": "missing",

    @Timeout(value = 1, unit = TimeUnit.SECONDS) // Very short timeout
    void testBroadcastTimeout() {
        // Configure for broadcast-only resolution with very short timeout
        when(mockConfig.getResolveOrder()).thenReturn(Arrays.asList(ResolverType.RESOLVER_BCAST));
        when(mockConfig.getNetbiosSoTimeout()).thenReturn(50); // Very short
        when(mockConfig.getNetbiosRetryCount()).thenReturn(1);

    @Benchmark
    public TemporalAccessor benchmarkFrom() {
        // benchmark an accessor that does not contain a timezone
        // this used to throw an exception earlier and thus was very very slow
        return DateFormatters.from(accessor);
    }

That's what all the systems with "login with Facebook, Google, X (Twitter), GitHub" use underneath.

### OAuth 1 { #oauth-1 }

There was an OAuth 1, which is very different from OAuth2, and more complex, as it included direct specifications on how to encrypt the communication.

It is not very popular or used nowadays.

OAuth2 doesn't specify how to encrypt the communication, it expects you to have your application served with HTTPS.

/// tip

### Preferred translations / glossary

Do not translate technical terms like path, route, request, response, query, body, cookie, and header, keep them as is.

- Suffixing is very important, when adding Turkish suffixes to the English words, do that based on the pronunciation of the word and with an apostrophe.

- Suffixes also changes based on what word comes next in Turkish too, here is an example:

# GraphQL { #graphql }

As **FastAPI** is based on the **ASGI** standard, it's very easy to integrate any **GraphQL** library also compatible with ASGI.

You can combine normal FastAPI *path operations* with GraphQL on the same application.

/// tip

**GraphQL** solves some very specific use cases.

It has **advantages** and **disadvantages** when compared to common **web APIs**.

 * cases the consuming thread must call [close] when it has finished reading the response
 * body.
 *
 * ### The response body can be consumed only once.
 *
 * This class may be used to stream very large responses. For example, it is possible to use this
 * class to read a response that is larger than the entire memory allocated to the current process.