* In many cases, it's better to understand their **underlying problem or use case**, because there might be a better way to solve it than what they are trying to do.

### Ask to close { #ask-to-close }

If they reply, there's a high chance you would have solved their problem, congrats, **you're a hero**! 🦸

* Now, if that solved their problem, you can ask them to:

    * In GitHub Discussions: mark the comment as the **answer**.

---
name: Feature request
about: Suggest an idea
title: ''
labels: enhancement
assignees: ''

---

Start by telling us what problem you’re trying to solve. Often a solution already exists!

    conflict with the copy of ListenableFuture in guava itself. If users are
    using an older version of Guava or a build system other than Gradle, they
    may see class conflicts. If so, they can solve them by manually excluding
    the listenablefuture artifact or manually forcing their build systems to
    use 9999.0-....
  </description>
  <build>
    <plugins>
      <plugin>

## Use Case { #use-case }

Let's start with an example **use case** and then see how to solve it with this.

Let's imagine that you have some **machine learning models** that you want to use to handle requests. 🤖

    conflict with the copy of ListenableFuture in guava itself. If users are
    using an older version of Guava or a build system other than Gradle, they
    may see class conflicts. If so, they can solve them by manually excluding
    the listenablefuture artifact or manually forcing their build systems to
    use 9999.0-....
  </description>
  <build>
    <plugins>
      <plugin>

/// info

Notice that we are only declaring one dependency in the *path operation function*, the `query_or_cookie_extractor`.

But **FastAPI** will know that it has to solve `query_extractor` first, to pass the results of that to `query_or_cookie_extractor` while calling it.

///

```mermaid
graph TB

query_extractor(["query_extractor"])

   * thus a motivated caller may be able to expose the reference to another thread that would then
   * call cancel() and be unable to cancel the delegate.
   * There are a number of ways to solve this, none of which are very pretty, and it is currently
   * believed to be a purely theoretical problem (since the other actions should supply sufficient
   * write-barriers).
   */

## Accessing the request body in an exception handler { #accessing-the-request-body-in-an-exception-handler }

/// tip

To solve this same problem, it's probably a lot easier to use the `body` in a custom handler for `RequestValidationError` ([Handling Errors](../tutorial/handling-errors.md#use-the-requestvalidationerror-body)).

...it has the same parameters as our previous `common_parameters`:

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

Those parameters are what **FastAPI** will use to "solve" the dependency.

In both cases, it will have:

* An optional `q` query parameter that is a `str`.
* A `skip` query parameter that is an `int`, with a default of `0`.

This tutorial shows you how to use **FastAPI** with most of its features, step by step.

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 }