Der Exceptionhandler erhält einen `Request` und die Exception.

{* ../../docs_src/handling_errors/tutorial004_py39.py hl[2,14:19] *}

Wenn Sie nun zu `/items/foo` gehen, erhalten Sie anstelle des standardmäßigen JSON-Fehlers mit:

```JSON
{
    "detail": [
        {
            "loc": [
                "path",
                "item_id"
            ],

        if ((createOptions & 0x0001) == 0) {
            this.createOptions = createOptions | 0x0040;
        } else {
            this.createOptions = createOptions;
        }
        this.impersonationLevel = 0x02; // As seen on NT :~)
        this.securityFlags = (byte) 0x03; // SECURITY_CONTEXT_TRACKING | SECURITY_EFFECTIVE_ONLY
    }

    /**
     * {@inheritDoc}
     *

There is no cancellation propagation for single payload requests.
When the context is canceled, the request will return at once with an appropriate error.
However, the remote call will not see the cancellation - as can be seen from the 'missing' context on the handler.
The result will be discarded.

### Typed handlers

Typed handlers are handlers that have a specific type for the request and response payloads.

  // the "short hash".
  //
  // The `keys`, `values`, and `entries` arrays always have the same size as each other. They can be
  // seen as fields of an imaginary `Entry` object like this:
  //
  // class Entry {
  //    int hash;
  //    Entry next;
  //    K key;
  //    V value;
  // }
  //

# Advanced Dependencies { #advanced-dependencies }

## Parameterized dependencies { #parameterized-dependencies }

All the dependencies we have seen are a fixed function or class.

But there could be cases where you want to be able to set parameters on the dependency, without having to declare many different functions or classes.

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

You can learn how to use them and how they are integrated into **FastAPI** later in the **Advanced User Guide**.

## Recap { #recap }

With what you have seen up to now, you can set up a secure **FastAPI** application using standards like OAuth2 and JWT.

In almost any framework handling the security becomes a rather complex subject quite quickly.

  // the "short hash".
  //
  // The `keys`, `values`, and `entries` arrays always have the same size as each other. They can be
  // seen as fields of an imaginary `Entry` object like this:
  //
  // class Entry {
  //    int hash;
  //    Entry next;
  //    K key;
  //    V value;
  // }
  //

   *
   * <p>This class is accessible but not supported in GWT as it references {@link
   * PermittedMetaException}.
   */
  protected final class MultiExceptionListIterator implements ListIterator<E> {
    // TODO: track seen elements when order isn't guaranteed
    // TODO: verify contents afterward
    // TODO: something shiny and new instead of Stack
    // TODO: test whether null is supported (create a Feature)
    /**

     *   <li>If this field's value == null because of unsafe publication, we know that it isn't the
     *       object associated with our thread, because if it was the publication wouldn't have been
     *       unsafe and we'd have seen our thread as the value. This state is also why a new
     *       ThreadConfinedTaskQueue object must be created for each inline execution, because
     *       observing a null thread does not mean the object is safe to reuse.

    }

    @Test
    public void testParseQueryWithTooManyTerms() {
        // Test query with more than MAX_QUERY_TERM_NUM (5) terms
        String query = "one two three four five six seven";
        String field = "content";
        String[] keywords = SuggestUtil.parseQuery(query, field);
        assertNotNull(keywords);
        assertEquals(0, keywords.length); // Should return empty array
    }