如何在颤动中发出带有url编码主体的HTTP POST请求？ [英] How to make HTTP POST request with url encoded body in flutter?

问题描述

我正在尝试以内容类型为url编码的形式发出发帖请求。当我写 body：json.encode（data）时，它会编码为纯文本。

I'm trying to make an post request in flutter with content type as url encoded. When I write body : json.encode(data), it encodes to plain text.

如果我写 body：data 我会收到错误 type'_InternalLinkedHashMap< String， dynamic>'不是类型转换类型'String'的子类型

If I write body: data I get the error type '_InternalLinkedHashMap<String, dynamic>' is not a subtype of type 'String' in type cast

这是数据对象

var match = {
  "homeTeam": {"team": "Team A"},
  "awayTeam": {"team": "Team B"}
};

我的请求

var response = await post(Uri.parse(url),
    headers: {
      "Accept": "application/json",
      "Content-Type": "application/x-www-form-urlencoded"
    },
    body: match,
    encoding: Encoding.getByName("utf-8"));

推荐答案

您需要添加三个附加步骤：
首先，您需要将JSON映射转换为字符串（使用json.encode）
然后，如果要将其作为application / x-www-form-urlencoded发送，则需要对其进行Uri编码。
最后，您需要提供要发布名称的参数。

You need to add three additional steps: First, you need to convert the JSON map to a String (using json.encode) Then you need to Uri encode it if you want to send it as application/x-www-form-urlencoded. Lastly, you need to give the parameter that you are posting a name.

例如（请注意，这是使用dart：io HttpClient，但基本相同） ：

For example (note, this is using the dart:io HttpClient, but it's basically the same):

  Future<HttpClientResponse> foo() async {
    Map<String, dynamic> jsonMap = {
      'homeTeam': {'team': 'Team A'},
      'awayTeam': {'team': 'Team B'},
    };
    String jsonString = json.encode(jsonMap); // encode map to json
    String paramName = 'param'; // give the post param a name
    String formBody = paramName + '=' + Uri.encodeQueryComponent(jsonString);
    List<int> bodyBytes = utf8.encode(formBody); // utf8 encode
    HttpClientRequest request =
        await _httpClient.post(_host, _port, '/a/b/c');
    // it's polite to send the body length to the server
    request.headers.set('Content-Length', bodyBytes.length.toString());
    // todo add other headers here
    request.add(bodyBytes);
    return await request.close();
  }

以上是针对dart：io版本的（当然，您可以在Flutter中使用）
如果您想使用package：http版本，则需要稍微调整一下Map。正文必须是Map< String，String>。您需要确定所需的POST参数。您是否想要两个：homeTeam和awayTeam？还是一个，例如teamJson？

The above is for the dart:io version (which, of course, you can use in Flutter) If you would like to stick with the package:http version, then you need to tweak your Map a bit. body must be a Map<String, String>. You need to decide what you want as your POST parameters. Do you want two: homeTeam and awayTeam? or one, say, teamJson?

此代码

  Map<String, String> body = {
    'name': 'doodle',
    'color': 'blue',
    'homeTeam': json.encode(
      {'team': 'Team A'},
    ),
    'awayTeam': json.encode(
      {'team': 'Team B'},
    ),
  };

  Response r = await post(
    url,
    body: body,
  );

通过网络生成

name = doodle& color = blue& homeTeam =％7B％22team％22％3A％22Team + A％22％7D& awayTeam =％7B％22team％22％3A％22Team + B％22％7D

name=doodle&color=blue&homeTeam=%7B%22team%22%3A%22Team+A%22%7D&awayTeam=%7B%22team%22%3A%22Team+B%22%7D

或者，此

  Map<String, String> body = {
    'name': 'doodle',
    'color': 'blue',
    'teamJson': json.encode({
      'homeTeam': {'team': 'Team A'},
      'awayTeam': {'team': 'Team B'},
    }),
  };

  Response r = await post(
    url,
    body: body,
  );

通过网络生成

name = doodle& color = blue& teamJson =％7B％22homeTeam％22％3A％7B％22team％22％3A％22Team + A％22％7D％2C％22awayTeam％22％3A％7B％22team％22％3A％22Team + B％22％7D％7D

name=doodle&color=blue&teamJson=%7B%22homeTeam%22%3A%7B%22team%22%3A%22Team+A%22%7D%2C%22awayTeam%22%3A%7B%22team%22%3A%22Team+B%22%7D%7D

package：http客户端负责：对Uri.encodeQueryComponent进行编码，对utf8进行编码（请注意，这是默认设置，因此无需指定它）并在Content-Length标头中发送长度。您仍然必须进行json编码。

the package:http client takes care of: encoding the Uri.encodeQueryComponent, utf8 encoding (note that that's the default, so no need to specify it) and sending the length in the Content-Length header. You must still do the json encoding.

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