# Handling Errors

There are many situations in which you need to notify an error to a client that is using your API.

This client could be a browser with a frontend, a code from someone else, an IoT device, etc.

You could need to tell the client that:

* The client doesn't have enough privileges for that operation.
* The client doesn't have access to that resource.
* The item the client was trying to access doesn't exist.
* etc.

     * This method is called automatically when using try-with-resources statements.
     *
     * <p>The default implementation does nothing. Subclasses should override this method
     * if they need to perform cleanup operations.</p>
     *
     * @throws InvokerException if an error occurs while closing the {@link Invoker}
     */
    @Override
    default void close() throws InvokerException {}

 * <p>
 * Unlike {@link ModelSource}, this interface supports loading of parent POM(s) from the same backing store and allows
 * construction of MavenProject instances without the need to have parent POM(s) available from local or remote
 * repositories.
 * <p>
 * ModelSource2 instances are cached in {@link ModelBuildingRequest#getModelCache()}. Implementations must guarantee

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

///

/// note

This is supported since FastAPI version `0.113.0`. 🤓

///

## Pydantic Models for Forms

You just need to declare a **Pydantic model** with the fields you want to receive as **form fields**, and then declare the parameter as `Form`:

//// tab | Python 3.9+

```Python hl_lines="9-11  15"

* Add more granular permission controls with OAuth2 scopes where needed.
* ...etc.

Nevertheless, you might have a very specific use case where you really need to disable the API docs for some environment (e.g. for production) or depending on configurations from environment variables.

## Conditional OpenAPI from settings and env vars

	RedirectDNS  bool `json:"REDIRECT_DNS"`
	// If true, TPROXY will be used for redirection. Else, REDIRECT will be used.
	// Currently, this is treated as a feature flag, but may be promoted to a permanent feature if there is a need.
	TPROXYRedirection bool `json:"TPROXY_REDIRECTION"`
}

type IptablesConfigurator struct {
	ext    dep.Dependencies
	nlDeps NetlinkDependencies
	cfg    *Config
	iptV   dep.IptablesVersion

    extends AbstractFuture<V> {
  /*
   * In the GWT versions of the methods (below), every exceptionType parameter is required to be
   * Class<Throwable>. To handle only certain kinds of exceptions under GWT, you'll need to write
   * your own instanceof tests.
   */

  public final FluentFuture<V> catching(
      Class<Throwable> exceptionType,
      Function<? super Throwable, ? extends V> fallback,
      Executor executor) {

   * a duration in order to call a legacy API which requires a {@code long, TimeUnit} pair.
   */
  @SuppressWarnings({
    // We use this method only for cases in which we need to decompose to primitives.
    "GoodTime-ApiWithNumericTimeUnit",
    "GoodTime-DecomposeToPrimitive",
    // We use this method only from within APIs that require a Duration.
    "Java7ApiChecker",
  })

abstract class GwtFuturesCatchingSpecialization {
  /*
   * In the GWT versions of the methods (below), every exceptionType parameter is required to be
   * Class<Throwable>. To handle only certain kinds of exceptions under GWT, you'll need to write
   * your own instanceof tests.
   */

  public static <V extends @Nullable Object> ListenableFuture<V> catching(
      ListenableFuture<? extends V> input,
      Class<Throwable> exceptionType,

ret=$?
if [ $ret -ne 0 ]; then
	echo "BUG: expected no 'diff' after replication: $out"
	exit 1
fi

sitea_count=$(cat /tmp/sitea_dirs.txt | wc -l) # need to do it this way to avoid filename in the output
siteb_count=$(cat /tmp/siteb_dirs.txt | wc -l) # need to do it this way to avoid filename in the output
sitea_out=$(cat /tmp/sitea_dirs.txt)
siteb_out=$(cat /tmp/siteb_dirs.txt)

if [ $sitea_count -ne 0 ]; then