{* ../../docs_src/request_files/tutorial001_an_py310.py hl[9] *}

/// info

`File` is a class that inherits directly from `Form`.

But remember that when you import `Query`, `Path`, `File` and others from `fastapi`, those are actually functions that return special classes.

///

/// tip

   * https://github.com/jspecify/jspecify-reference-checker/blob/61aafa4ae52594830cfc2d61c8b113009dbdb045/src/main/java/com/google/jspecify/nullness/NullSpecTransfer.java#L789
   * and https://github.com/jspecify/jspecify/issues/490.
   *
   * (Perhaps it should also have required that its cause was a RuntimeException. However, that

  <exclude name="**/testing/**"/>
</source>

<!--
    We used to set this only for packages that had manual supersource. That
    worked everywhere that I know of except for one place: when running the GWT
    util.concurrent tests under Guava.

    The problem is that GWT responds poorly to two .gwt.xml files in the same
    Java package; see

Therefore, it lists pre-conditions and actions that should be performed to
resolve and fix a reported vulnerability.

## Vulnerability Management Process

The vulnerability management process requires that the vulnerability report
contains the following information:

- The project / component that contains the reported vulnerability.
- A description of the vulnerability. In particular, the type of the

   * being deleted. This can happen if, after checking that a file is a directory (and not a
   * symbolic link), that directory is deleted and replaced by a symbolic link to an outside
   * directory before the call that opens the directory to read its entries. File systems that
   * support {@code SecureDirectoryStream} do not have this vulnerability.
   */
  ALLOW_INSECURE

   * defaultValue)}.
   *
   * @param map source map that determines the function behavior
   * @param defaultValue the value to return for inputs that aren't map keys
   * @return function that returns {@code map.get(a)} when {@code a} is a key, or {@code
   *     defaultValue} otherwise
   */
  public static <K extends @Nullable Object, V extends @Nullable Object> Function<K, V> forMap(

 *
 * Implementations authenticate by returning a follow-up request that includes an authorization
 * header, or they may decline the challenge by returning null. In this case the unauthenticated
 * response will be returned to the caller that triggered it.
 *
 * Implementations should check if the initial request already included an attempt to
 * authenticate. If so it is likely that further attempts will not be useful and the authenticator

  <exclude name="**/testing/**"/>
</source>

<!--
    We used to set this only for packages that had manual supersource. That
    worked everywhere that I know of except for one place: when running the GWT
    util.concurrent tests under Guava.

    The problem is that GWT responds poorly to two .gwt.xml files in the same
    Java package; see

            return false;
        }

        UpgradedProperty that = (UpgradedProperty) o;
        return containingType.equals(that.containingType) && propertyName.equals(that.propertyName) && methodName.equals(that.methodName) && methodDescriptor.equals(that.methodDescriptor) && replacedAccessors.equals(that.replacedAccessors);
    }

    @Override
    public int hashCode() {

```JSON
{"item_id":3}
```

/// check

Notice that the value your function received (and returned) is `3`, as a Python `int`, not a string `"3"`.

So, with that type declaration, **FastAPI** gives you automatic request <dfn title="converting the string that comes from an HTTP request into Python data">"parsing"</dfn>.

///

## Data validation { #data-validation }