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 }

        // To keep this helper simple, return base and let the caller append/pad and inject ctx.
        return base;
    }

    /**
     * Build a full SMB2 packet combining header and provided body, optionally injecting context bytes.
     */
    private static byte[] buildPacket(byte[] header, byte[] body, Integer ctxOffsetFromHeader, byte[] ctxBytes) {
        int totalLen;
        if (ctxOffsetFromHeader != null && ctxBytes != null) {

			// Set decoded length to a large value out of int64 range to simulate parse failure.
			req.Header.Set("x-amz-decoded-content-length", "9999999999999999999999")
		}

		if err != nil {
			t.Fatalf("Error injecting faults into the request: <ERROR> %v.", err)
		}

		// Since `apiRouter` satisfies `http.Handler` it has a ServeHTTP to execute the logic of the handler.

It achieves something somewhat similar to what can be done with Flask-apispec.

It has an integrated dependency injection system, inspired by Angular 2. It requires pre-registering the "injectables" (like all the other dependency injection systems I know), so, it adds to the verbosity and code repetition.

## Code size { #code-size }

This example might seem verbose. Keep in mind that we are mixing security, data models, utility functions and *path operations* in the same file.

But here's the key point.

The security and dependency injection stuff is written once.

* Any keyword arguments that should be passed to the task function (`message="some notification"`).

## Dependency Injection { #dependency-injection }

Using `BackgroundTasks` also works with the dependency injection system, you can declare a parameter of type `BackgroundTasks` at multiple levels: in a *path operation function*, in a dependency (dependable), in a sub-dependency, etc.

### Dependency Injection { #dependency-injection }

FastAPI includes an extremely easy to use, but extremely powerful <abbr title='also known as "components", "resources", "services", "providers"'><strong>Dependency Injection</strong></abbr> system.

* Even dependencies can have dependencies, creating a hierarchy or **"graph" of dependencies**.

        fallback to 1.x behavior.
*   TensorFlow Lite
    *   Move from `tensorflow/contrib/lite` to `tensorflow/lite`.
    *   Add experimental Java API for injecting TensorFlow Lite delegates
    *   Add support for strings in TensorFlow Lite Java API.
*   `tf.contrib`:
    *   Add Apache Ignite Filesystem plugin to support accessing Apache IGFS.

 * either express or implied. See the License for the specific language
 * governing permissions and limitations under the License.
 */
package org.codelibs.fess.exception;

/**
 * Exception thrown when a dependency injection container or component is not available.
 * This exception indicates that the required container or a specific component within it cannot be accessed.
 */
public class ContainerNotAvailableException extends FessSystemException {

async def needy_dependency(fresh_value: str = Depends(get_value, use_cache=False)):
    return {"fresh_value": fresh_value}
```

////

## Recap { #recap }

Apart from all the fancy words used here, the **Dependency Injection** system is quite simple.

Just functions that look the same as the *path operation functions*.

But still, it is very powerful, and allows you to declare arbitrarily deeply nested dependency "graphs" (trees).

/// tip