HTML フォーム（`<form></form>`）がサーバーにデータを送る方法は、そのデータに対して通常「特別な」エンコーディングを用い、JSON とは異なります。

**FastAPI** は JSON ではなく、適切な場所からそのデータを読み取るようにします。

/// note | 技術詳細

ファイルを含まない場合、フォームからのデータは通常「メディアタイプ」`application/x-www-form-urlencoded` でエンコードされます。

ただしフォームにファイルが含まれる場合は、`multipart/form-data` としてエンコードされます。`File` を使うと、**FastAPI** はボディ内の正しい部分からファイルを取得すべきであると認識します。

	if err != nil {
		return "", fmt.Errorf("new request err (/login): %v", err)
	}
	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	_, err = dexClient.Do(req)
	if err != nil {
		return "", fmt.Errorf("post form err: %v", err)
	}
	// fmt.Printf("resp: %#v %#v\n", resp.StatusCode, resp.Header)
	// bodyBuf, err := io.ReadAll(resp.Body)

Et.href,ce.extend({active:0,lastModified:{},etag:{},ajaxSettings:{url:Et.href,type:"GET",isLocal:/^(?:about|app|app-storage|.+-extension|file|res|widget):$/.test(Et.protocol),global:!0,processData:!0,async:!0,contentType:"application/x-www-form-urlencoded; charset=UTF-8",accepts:{"*":zt,text:"text/plain",html:"text/html",xml:"application/xml, text/xml",json:"application/json, text/javascript"},contents:{xml:/\bxml\b/,html:/\bhtml/,json:/\bjson\b/},responseFields:{xml:"responseXML",text:"response...

Et.href,ce.extend({active:0,lastModified:{},etag:{},ajaxSettings:{url:Et.href,type:"GET",isLocal:/^(?:about|app|app-storage|.+-extension|file|res|widget):$/.test(Et.protocol),global:!0,processData:!0,async:!0,contentType:"application/x-www-form-urlencoded; charset=UTF-8",accepts:{"*":zt,text:"text/plain",html:"text/html",xml:"application/xml, text/xml",json:"application/json, text/javascript"},contents:{xml:/\bxml\b/,html:/\bhtml/,json:/\bjson\b/},responseFields:{xml:"responseXML",text:"response...

            generated OpenAPI, but currently it doesn't affect the parsing of the data.
            """
        ),
    ] = "application/x-www-form-urlencoded",
    alias: Annotated[
        str | None,
        Doc(
            """
            An alternative name for the parameter field.

the API, in 1.2 you will either receive a 415 or 406 error.
The only client
this is known to affect is curl when you use -d with JSON but don't set a
content type, helpfully sends "application/x-www-urlencoded", which is not
correct.
Other client authors should double check that you are sending proper
accept and content type headers, or set no value (in which case JSON is the
default).
An example using curl:

   *
   * @since 15.0
   */
  public static final MediaType EPUB = createConstant(APPLICATION_TYPE, "epub+zip");

  public static final MediaType FORM_DATA =
      createConstant(APPLICATION_TYPE, "x-www-form-urlencoded");

  /**
   * As described in <a href="https://www.rsa.com/rsalabs/node.asp?id=2138">PKCS #12: Personal
   * Information Exchange Syntax Standard</a>, PKCS #12 defines an archive file format for storing

				"text/x-rexx",
				"text/x-ruby",
				"text/x-scala",
				"text/x-scheme",
				"text/x-sed",
				"text/x-sql",
				"text/x-setext",
				"text/x-stsrc",
				"text/x-tcl",
				"text/x-uuencode",
				"text/x-vbasic",
				"text/x-vbdotnet",
				"text/x-vbscript",
				"text/x-vcalendar",
				"text/x-vcard",
				"text/x-verilog",
				"text/x-vhdl",
				"text/x-web-markdown",