# Dependencies in path operation decorators { #dependencies-in-path-operation-decorators }

In some cases you don't really need the return value of a dependency inside your *path operation function*.

Or the dependency doesn't return a value.

But you still need it to be executed/solved.

For those cases, instead of declaring a *path operation function* parameter with `Depends`, you can add a `list` of `dependencies` to the *path operation decorator*.

# Form Data { #form-data }

When you need to receive form fields instead of JSON, you can use `Form`.

/// info

To use forms, first install <a href="https://github.com/Kludex/python-multipart" class="external-link" target="_blank">`python-multipart`</a>.

Make sure you create a [virtual environment](../virtual-environments.md){.internal-link target=_blank}, activate it, and then install it, for example:

```console
$ pip install python-multipart
```

# Response - Change Status Code { #response-change-status-code }

You probably read before that you can set a default [Response Status Code](../tutorial/response-status-code.md){.internal-link target=_blank}.

But in some cases you need to return a different status code than the default.

## Use case { #use-case }

For example, imagine that you want to return an HTTP status code of "OK" `200` by default.

        if (Objects.equals(key, keys[next])) {
          int oldValue = values[next];

          if (last == UNSET) {
            // we need to update the root link from table[]
            table[tableIndex] = getNext(entries[next]);
          } else {
            // we need to update the link from the chain
            entries[last] = swapNext(entries[last], getNext(entries[next]));
          }

# JSON Compatible Encoder { #json-compatible-encoder }

There are some cases where you might need to convert a data type (like a Pydantic model) to something compatible with JSON (like a `dict`, `list`, etc).

For example, if you need to store it in a database.

For that, **FastAPI** provides a `jsonable_encoder()` function.

## Using the `jsonable_encoder` { #using-the-jsonable-encoder }

   * does not need to be escaped. When called as part of an escaping operation, the given code point
   * is guaranteed to be in the range {@code 0 <= cp <= Character#MAX_CODE_POINT}.
   *
   * <p>If an empty array is returned, this effectively strips the input character from the
   * resulting text.
   *
   * <p>If the character does not need to be escaped, this method should return {@code null}, rather

import java.lang.annotation.Target;

/**
 * Disables Animal Sniffer's checking of compatibility with older versions of Java/Android.
 *
 * <p>Each package's copy of this annotation needs to be listed in our {@code pom.xml}.
 */
@Target({METHOD, CONSTRUCTOR, TYPE, FIELD})

import java.lang.annotation.Target;

/**
 * Disables Animal Sniffer's checking of compatibility with older versions of Java/Android.
 *
 * <p>Each package's copy of this annotation needs to be listed in our {@code pom.xml}.
 */
@Target({METHOD, CONSTRUCTOR, TYPE, FIELD})

And then you can set headers in that *temporal* response object.

{* ../../docs_src/response_headers/tutorial002_py39.py hl[1, 7:8] *}

And then you can return any object you need, as you normally would (a `dict`, a database model, etc).

And if you declared a `response_model`, it will still be used to filter and convert the object you returned.

        // TODO currently this is first wins, but really we should take the latest by comparing either the
        // snapshot timestamp, or some other timestamp later encoded into the metadata.
        // TODO this needs to be repeated here so the merging doesn't interfere with the written metadata
        //  - we'd be much better having a pristine input, and an ongoing metadata for merging instead