## 数值校验：大于等于

使用 `Query` 和 `Path`（以及你将在后面看到的其他类）可以声明字符串约束，但也可以声明数值约束。

像下面这样，添加 `ge=1` 后，`item_id` 将必须是一个大于（`g`reater than）或等于（`e`qual）`1` 的整数。

```Python hl_lines="8"
{!../../../docs_src/path_params_numeric_validations/tutorial004.py!}
```

## 数值校验：大于和小于等于

同样的规则适用于：

* `gt`：大于（`g`reater `t`han）
* `le`：小于等于（`l`ess than or `e`qual）

```Python hl_lines="9"

/**
 * Component for use by the <code>maven-toolchains-plugin</code> only.
 * It provides API: <ol>
 * <li>to retrieve every toolchains available in user settings,</li>
 * <li>to store chosen toolchain into build context for later use by toolchain-aware plugins.</li>
 * </ol>
 *
 * @since 2.0.9
 * @see ToolchainManager#getToolchainFromBuildContext(String, MavenSession)
 */
public interface ToolchainManagerPrivate {

    /**

А также вы можете добавить валидацию числовых данных:

* `gt`: больше (`g`reater `t`han)
* `ge`: больше или равно (`g`reater than or `e`qual)
* `lt`: меньше (`l`ess `t`han)
* `le`: меньше или равно (`l`ess than or `e`qual)

!!! info "Информация"

    assertFalse(future.isCancelled());
  }

  public void testSetValue_simpleThreaded() throws Exception {
    SettableFuture<Integer> future = SettableFuture.create();
    assertTrue(future.set(42));
    // Later attempts to set the future should return false.
    assertFalse(future.set(23));
    assertFalse(future.setException(new Exception("bar")));
    assertFalse(future.setFuture(SettableFuture.<Integer>create()));

    assertFalse(future.isCancelled());
  }

  public void testSetValue_simpleThreaded() throws Exception {
    SettableFuture<Integer> future = SettableFuture.create();
    assertTrue(future.set(42));
    // Later attempts to set the future should return false.
    assertFalse(future.set(23));
    assertFalse(future.setException(new Exception("bar")));
    assertFalse(future.setFuture(SettableFuture.<Integer>create()));

// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

   * (used as the reference iterator) against a {@code PeekingIterator} that *wraps* such an
   * iterator (used as the target iterator).
   *
   * <p>This IteratorTester makes copies of the master so that it can later verify that {@link
   * PeekingIterator#remove()} removes the same elements as the reference's iterator {@code
   * #remove()}.
   */

* Then it returns the **response**.

!!! note "Technical Details"
    If you have dependencies with `yield`, the exit code will run *after* the middleware.

    If there were any background tasks (documented later), they will run *after* all the middleware.

## Create a middleware

To create a middleware you use the decorator `@app.middleware("http")` on top of a function.

The middleware function receives:

* The `request`.

  <parent>
    <groupId>org.sonatype.mavenbook.multi</groupId>
    <artifactId>parent</artifactId>
  </parent>
  <artifactId>simple-parent</artifactId>
  <packaging>pom</packaging>
  <name>Multi Chapter Simple Parent Project</name>

  <modules>
    <module>simple-weather</module>
    <module>simple-webapp</module>

    <!-- On purpose at the end, project graph is responsible for ordering -->

    And Pydantic's `Field` returns an instance of `FieldInfo` as well.

    `Body` also returns objects of a subclass of `FieldInfo` directly. And there are others you will see later that are subclasses of the `Body` class.

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

!!! tip