# `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

///

### 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

Here you will see different recipes or "how to" guides for **several topics**.

Most of these ideas would be more or less **independent**, and in most cases you should only need to study them if they apply directly to **your project**.

If something seems interesting and useful to your project, go ahead and check it, but otherwise, you might probably just skip them.

/// tip

Then we use the request directly, and extract the body as `bytes`. This means that FastAPI won't even try to parse the request payload as JSON.

And then in our code, we parse that YAML content directly, and then we are again using the same Pydantic model to validate the YAML content:

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).

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.

 * FILE_WRITE_DATA</code>) and the target file has the following security
 * descriptor ACEs:
 * <pre>
 * Allow WNET\alice     0x001200A9  Direct
 * Allow Administrators 0x001F01FF  Inherited
 * Allow SYSTEM         0x001F01FF  Inherited
 * </pre>
 * the access check would fail because the direct ACE has an access mask
 * of <code>0x001200A9</code> which doesn't have the

}

// isDirectiveValid - check if tagging-directive is valid.
func isDirectiveValid(v string) bool {
	// Check if set metadata-directive is valid.
	return isDirectiveCopy(v) || isDirectiveReplace(v)
}

// Check if the directive COPY is requested.
func isDirectiveCopy(value string) bool {
	// By default if directive is not set we
	// treat it as 'COPY' this function returns true.

import org.junit.Ignore;

/**
 * A generic JUnit test which tests {@link Map#computeIfPresent}. Can't be invoked directly; please
 * see {@link com.google.common.collect.testing.MapTestSuiteBuilder}.
 *
 * @author Louis Wasserman
 */
@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.