-  The API may be available in the public Keras API under a different name, so make sure to look for it on keras.io or TensorFlow docs and switch to the public version.
        -  It could also be a simple python or TF utility that you could easily copy over to your own codebase. In those case, just make it your own!

The security and dependency injection stuff is written once.

And you can make it as complex as you want. And still, have it written only once, in a single place. With all the flexibility.

But you can have thousands of endpoints (*path operations*) using the same security system.

And all of them (or any portion of them that you want) can take advantage of re-using these dependencies or any other dependencies you create.

//	db.Where(User{Name: "non_existing"}).Attrs(User{Email: "fake@fake.org"}).FirstOrInit(&user)
//	// user -> User{Name: "non_existing", Email: "fake@fake.org"}
//
//	// assign email regardless of if record is found
//	db.Where(User{Name: "jinzhu"}).Assign(User{Email: "fake@fake.org"}).FirstOrInit(&user)
//	// user -> User{Name: "jinzhu", Age: 20, Email: "fake@fake.org"}

### Create a dependency, or "dependable" { #create-a-dependency-or-dependable }

Let's first focus on the dependency.

It is just a function that can take all the same parameters that a *path operation function* can take:

{* ../../docs_src/dependencies/tutorial001_an_py310.py hl[8:9] *}

That's it.

**2 lines**.

And it has the same shape and structure that all your *path operation functions* have.

//	db.Where(User{Name: "non_existing"}).Assign(User{Email: "fake@fake.org"}).FirstOrInit(&user)
//	// user -> User{Name: "non_existing", Email: "fake@fake.org"}
//
//	// assign email regardless of if record is found
//	db.Where(User{Name: "jinzhu"}).Assign(User{Email: "fake@fake.org"}).FirstOrInit(&user)
//	// user -> User{Name: "jinzhu", Age: 20, Email: "fake@fake.org"}
//

				ok = false // broke compatibility
			}
		case len(required) == 0 || (len(features) > 0 && required[0] > features[0]):
			newFeature := take(&features)
			fmt.Fprintf(w, "+%s\n", newFeature)
			ok = false // feature not in api/next/*
		default:
			take(&required)
			take(&features)
		}
	}

	return ok
}

// aliasReplacer applies type aliases to earlier API files,

* Decompressing gzip-compressed request bodies.
* Automatically logging all request bodies.

## Handling custom request body encodings { #handling-custom-request-body-encodings }

Let's see how to make use of a custom `Request` subclass to decompress gzip requests.

And an `APIRoute` subclass to use that custom request class.

### Create a custom `GzipRequest` class { #create-a-custom-gziprequest-class }

/// tip

For this, use the Python standard module <a href="https://docs.python.org/3/library/secrets.html" class="external-link" target="_blank">`secrets`</a> to check the username and password.

`secrets.compare_digest()` needs to take `bytes` or a `str` that only contains ASCII characters (the ones in English), this means it wouldn't work with characters like `á`, as in `Sebastián`.

But `OAuth2PasswordRequestForm` is just a class dependency that you could have written yourself, or you could have declared `Form` parameters directly.

But as it's a common use case, it is provided by **FastAPI** directly, just to make it easier.

///

### Use the form data { #use-the-form-data }

/// tip

import org.junit.rules.TestRule
import org.junit.runner.Description
import org.junit.runners.model.Statement

/**
 * A log handler that records which log messages were published so that a calling test can make
 * assertions about them.
 */
class TestLogHandler(
  private val logger: Logger,
) : TestRule,
  BeforeEachCallback,
  AfterEachCallback {