## Importer `Header` { #import-header }

Commencez par importer `Header` :

{* ../../docs_src/header_params/tutorial001_an_py310.py hl[3] *}

## Déclarer des paramètres `Header` { #declare-header-parameters }

Déclarez ensuite les paramètres d'en-tête en utilisant la même structure qu'avec `Path`, `Query` et `Cookie`.

   
   *Please let us know if this helps.*
   
windows_comment: >
   From the stack trace it looks like you are hitting windows path length limit.
      * Try to disable path length limit on Windows 10.
        * Refer [disable path length limit instructions guide.](https://mspoweruser.com/ntfs-260-character-windows-10/)
   

Imaginemos que quieres obtener la dirección IP/host del cliente dentro de tu *path operation function*.

Para eso necesitas acceder al request directamente.

{* ../../docs_src/using_request_directly/tutorial001_py310.py hl[1,7:8] *}

Al declarar un parámetro de *path operation function* con el tipo siendo `Request`, **FastAPI** sabrá pasar el `Request` en ese parámetro.

/// tip | Consejo

    }

    // Happy path: getDfsReferrals returns referral, verify arguments captured
    @Test
    @DisplayName("getDfsReferrals returns data and receives correct args")
    void getDfsReferrals_happy() throws Exception {
        when(transport.getDfsReferrals(any(), any(), any(), any(), anyInt())).thenReturn(referral);

        String name = "\\\\server\\\\share\\\\path"; // UNC-like DFS path

            return url.toString();
        }

        private void concatPath(StringBuilder url, String path) {
            if (!path.isEmpty()) {
                boolean initialUrlEndsWithSlash = url.charAt(url.length() - 1) == '/';
                boolean pathStartsWithSlash = path.charAt(0) == '/';

                if (pathStartsWithSlash) {
                    if (initialUrlEndsWithSlash) {

                }
            }
            return builder.build()
        }

        private
        fun processDirectory(dir: Path, builder: Trie.Builder) {
            Files.walkFileTree(dir, object : SimpleFileVisitor<Path>() {
                override fun visitFile(file: Path, attrs: BasicFileAttributes): FileVisitResult {
                    val zipEntry = ZipEntry(dir.relativize(file).toString())

    try {
      val requestHeaders = stream.takeHeaders()
      var path: String? = null
      var i = 0
      val size = requestHeaders.size
      while (i < size) {
        if (requestHeaders.name(i) == Header.TARGET_PATH_UTF8) {
          path = requestHeaders.value(i)
          break
        }
        i++
      }
      if (path == null) {
        // TODO: send bad request error
        throw AssertionError()

        ),
    ],
) -> Any:
    """
    Declare a path parameter for a *path operation*.

    Read more about it in the
    [FastAPI docs for Path Parameters and Numeric Validations](https://fastapi.tiangolo.com/tutorial/path-params-numeric-validations/).

    ```python
    from typing import Annotated

    from fastapi import FastAPI, Path

    app = FastAPI()


    @app.get("/items/{item_id}")

    String getShare();

    /**
     * Get the number of characters from the UNC path that were consumed by this referral
     *
     * @return the number of characters from the unc path that were consumed by this referral
     */
    int getPathConsumed();

    /**
     * Get the replacement path for this referral
     *
     * @return the replacement path for this referal
     */
    String getPath();

    /**

ItemsService.createItemItemsPost({name: "Plumbus", price: 5})
```

...that's because the client generator uses the OpenAPI internal **operation ID** for each *path operation*.

OpenAPI requires that each operation ID is unique across all the *path operations*, so FastAPI uses the **function name**, the **path**, and the **HTTP method/operation** to generate that operation ID, because that way it can make sure that the operation IDs are unique.