### Andere Hilfsfunktionen

# Extending OpenAPI { #extending-openapi }

There are some cases where you might need to modify the generated OpenAPI schema.

In this section you will see how.

## The normal process { #the-normal-process }

The normal (default) process, is as follows.

A `FastAPI` application (instance) has an `.openapi()` method that is expected to return the OpenAPI schema.

You can use the same dependency *functions* you use normally.

### Dependency requirements { #dependency-requirements }

They can declare request requirements (like headers) or other sub-dependencies:

{* ../../docs_src/dependencies/tutorial006_an_py39.py hl[8,13] *}

### Raise exceptions { #raise-exceptions }

These dependencies can `raise` exceptions, the same as normal dependencies:

This means that instead of the normal process of your users sending requests to your API, it's **your API** (or your app) that could **send requests to their system** (to their API, their app).

This is normally called a **webhook**.

## Webhooks steps { #webhooks-steps }

## What is "Form Data" { #what-is-form-data }

The way HTML forms (`<form></form>`) sends the data to the server normally uses a "special" encoding for that data, it's different from JSON.

**FastAPI** will make sure to read that data from the right place instead of JSON.

/// note | Technical Details

Data from forms is normally encoded using the "media type" `application/x-www-form-urlencoded` when it doesn't include files.

    @Override
    public void setUp() throws Exception {
        super.setUp();
        indexUpdateCallback = new FileListIndexUpdateCallbackImpl(null, null, 1);
    }

    /** Case 1: Normal merge (no duplicates) */
    public void test_mergeResponseData_noOverwrite() {
        Map<String, Object> dataMap = new HashMap<>();
        dataMap.put("a", "A0");
        Map<String, Object> responseDataMap = new HashMap<>();

### Diğer yardımcı fonksiyonlar

Doğrudan çağırdığınız diğer herhangi bir yardımcı fonksiyonu, normal "def" veya "async def" ile tanimlayabilirsiniz. FastAPI onu çağırma şeklinizi etkilemez.

### Other utility functions { #other-utility-functions }

Any other utility function that you call directly can be created with normal `def` or `async def` and FastAPI won't affect the way you call it.

                bufferIndex += ((AndXServerMessageBlock) andx).readAndXWireFormat(buffer, bufferIndex);
            } else {

                /*
                 * Just a plain smb. Read it as normal.
                 */

                buffer[bufferIndex++] = (byte) (andx.wordCount & 0xFF);

                if (andx.wordCount != 0 && andx.wordCount > 2) {

  public void testNoExceptionsThrown() throws IOException {
    Closer closer = new Closer(suppressor);

    TestCloseable c1 = closer.register(TestCloseable.normal());
    TestCloseable c2 = closer.register(TestCloseable.normal());
    TestCloseable c3 = closer.register(TestCloseable.normal());

    assertFalse(c1.isClosed());
    assertFalse(c2.isClosed());
    assertFalse(c3.isClosed());

    closer.close();