description: Tell us what happens
    validations:
      required: true
  - type: textarea
    id: expected-behavior
    attributes:
      label: Expected Behavior
      description: Tell us what should happen
    validations:
      required: true
  - type: textarea
    id: context
    attributes:
      label: Context (optional)
      description: |
        How has this issue affected you? What are you trying to accomplish?

 *
 * h3. plugins should be able to have specific metadata for a plugin model and that be translated -
 * dependencies - resources - configuration - extension points of plugins
 *
 * For a particular application plugin there will be a declarative descriptor for that plugin type.
 *
 * - nexus - the plugin class - UI to contribute - what JS to hook into the UI - what resources to

  - type: textarea
    id: current-behavior
    attributes:
      label: Current Behavior
      description: Tell us what happens
    validations:
      required: true
  - type: textarea
    id: expected-behavior
    attributes:
      label: Expected Behavior
      description: Tell us what should happen
    validations:
      required: true
  - type: textarea
    id: context
    attributes:

```

////

The last `CommonQueryParams`, in:

```Python
... Depends(CommonQueryParams)
```

...is what **FastAPI** will actually use to know what is the dependency.

It is from this one that FastAPI will extract the declared parameters and that is what FastAPI will actually call.

---

In this case, the first `CommonQueryParams`, in:

//// tab | Python 3.8+

```Python

import org.slf4j.LoggerFactory;

/**
 * Use an SLF4J {@link org.slf4j.ILoggerFactory} as a backing for a Plexus
 * {@link org.codehaus.plexus.logging.LoggerManager},
 * ignoring Plexus logger API parts that are not classical and probably not really used.
 *
 * @since 3.1
 */
public class Slf4jLoggerManager implements LoggerManager {

    private ILoggerFactory loggerFactory;

    public Slf4jLoggerManager() {

You could create an API with a *path operation* that could trigger a request to an *external API* created by someone else (probably the same developer that would be *using* your API).

The process that happens when your API app calls the *external API* is named a "callback". Because the software that the external developer wrote sends a request to your API and then your API *calls back*, sending a request to an *external API* (that was probably created by the same developer).

### FastAPI Data Filtering

Now, for FastAPI, it will see the return type and make sure that what you return includes **only** the fields that are declared in the type.

///

It will:

* Return that status code in the response.
* Document it as such in the OpenAPI schema (and so, in the user interfaces):

<img src="/img/tutorial/response-status-code/image01.png">

/// note

Some response codes (see the next section) indicate that the response does not have a body.

FastAPI knows this, and will produce OpenAPI docs that state there is no response body.

///

///

## Advanced User Guide

There is also an **Advanced User Guide** that you can read later after this **Tutorial - User guide**.

The **Advanced User Guide** builds on this one, uses the same concepts, and teaches you some extra features.

But you should first read the **Tutorial - User Guide** (what you are reading right now).

Let's imagine that we want to have a dependency that checks if the query parameter `q` contains some fixed content.

But we want to be able to parameterize that fixed content.

## A "callable" instance

In Python there's a way to make an instance of a class a "callable".

Not the class itself (which is already a callable), but an instance of that class.

To do that, we declare a method `__call__`: