RestSharp GET带JSON请求体无响应问题排查（.NET 4.8）

问题场景 #

用RestSharp发送带JSON请求体和Authorization安全令牌的GET请求下载文件，先获取响应。Postman里这个请求能正常触发文件保存提示，但自己写的代码运行后报错。

原错误代码 #

var client = new RestClient(url);
client.Timeout = -1;
var request = new RestRequest(Method.GET);
request.AddHeader("Authorization", token);
request.AddHeader("Content-Type", "application/json");
request.AddParameter("application/json", json, ParameterType.RequestBody);
IRestResponse response = client.Execute(request);

string responseMsg = "";
if (response.Content == "") 
    responseMsg = response.ErrorMessage
else
    responseMsg = response.Content
return responseMsg;

报错信息 #

HTTP verb GET does not support body

问题原因 #

GET请求携带请求体本身不符合HTTP规范，你用的RestSharp 106.15.0版本会严格校验这一点，所以直接抛出了错误。Postman对这类非规范请求兼容性更好，所以能正常跑通。

修正后的代码 #

因为唯一标识已经附加在请求端点里了，只需要保留Authorization请求头就行：

var client = new RestClient(url);
client.Timeout = -1;
var request = new RestRequest(Method.GET);
request.AddHeader("Authorization", token);
IRestResponse response = client.Execute(request);

内容的提问来源于stack exchange，提问作者Mick