## Install custom exception handlers { #install-custom-exception-handlers }

You can add custom exception handlers with <a href="https://www.starlette.io/exceptions/" class="external-link" target="_blank">the same exception utilities from Starlette</a>.

Let's say you have a custom exception `UnicornException` that you (or a library you use) might `raise`.

And you want to handle this exception globally with FastAPI.

  /**
   * Returns {@code true} if this fluent iterable contains any object for which {@code
   * equals(target)} is true.
   *
   * <p><b>{@code Stream} equivalent:</b> {@code stream.anyMatch(Predicate.isEqual(target))}.
   */
  public final boolean contains(@Nullable Object target) {
    return Iterables.contains(getDelegate(), target);
  }

  /**

  /**
   * Returns {@code true} if this fluent iterable contains any object for which {@code
   * equals(target)} is true.
   *
   * <p><b>{@code Stream} equivalent:</b> {@code stream.anyMatch(Predicate.isEqual(target))}.
   */
  public final boolean contains(@Nullable Object target) {
    return Iterables.contains(getDelegate(), target);
  }

  /**

                return request.getContentType() != null && request.getContentType().startsWith(MULTIPART_FORMDATA_TYPE);
            }

            @Override
            public void handle(String target, HttpServletRequest request, HttpServletResponse response, int dispatch)
                    throws java.io.IOException, ServletException {

      this.cacheUrlOverride = request.cacheUrlOverride
    }

    open fun url(url: HttpUrl): Builder =
      apply {
        this.url = url
      }

    /**
     * Sets the URL target of this request.
     *
     * @throws IllegalArgumentException if [url] is not a valid HTTP or HTTPS URL. Avoid this
     *     exception by calling [HttpUrl.parse]; it returns null for invalid URLs.
     */

      } catch (ClassCastException e) {
        return false;
      }
    }

    @Override
    int indexOf(@Nullable Object target) {
      if (contains(target)) {
        @SuppressWarnings("unchecked") // if it's contained, it's definitely a C
        C c = (C) requireNonNull(target);
        long total = 0;
        for (Range<C> range : ranges) {
          if (range.contains(c)) {

        }

        /**
         * Returns the type of path without indication about the target module.
         * This is usually {@link #PATCH_MODULE}.
         *
         * @return type of path without indication about the target module
         */
        @Nonnull
        public JavaPathType rawType() {
            return JavaPathType.this;
        }

    }
    Object result;
    try {
      result = supplier.get();
    } catch (Throwable t) {
      if (predicate.apply(t)) {
        // We are careful to set up INSTANCE_OF to match each Predicate to its target Class.
        @SuppressWarnings("unchecked")
        T caught = (T) t;
        return caught;
      }
      throw new AssertionError(

* `limit`, ein optionales `int`.

/// tip | Tipp

Sie können auch `Enum`s verwenden, auf die gleiche Weise wie mit [Pfad-Parametern](path-params.md#vordefinierte-parameterwerte){.internal-link target=_blank}.

{* ../../docs_src/path_params_numeric_validations/tutorial006.py hl[11] *}

## 🌃

⏮️ `Query`, `Path` (& 🎏 👆 🚫 👀) 👆 💪 📣 🗃 & 🎻 🔬 🎏 🌌 ⏮️ [🔢 🔢 & 🎻 🔬](query-params-str-validations.md){.internal-link target=_blank}.

& 👆 💪 📣 🔢 🔬:

* `gt`: `g`🅾 `t`👲
* `ge`: `g`🅾 🌘 ⚖️ `e`🅾
* `lt`: `l`👭 `t`👲
* `le`: `l`👭 🌘 ⚖️ `e`🅾

/// info

`Query`, `Path`, & 🎏 🎓 👆 🔜 👀 ⏪ 🏿 ⚠ `Param` 🎓.