SharePoint REST-为什么更新元数据返回204而不是200？

根据Dynamics Web API文档，默认值为更新数据而不返回更新的结果。这就是为什么您获得状态代码204的原因。为了获取返回的数据，您将需要prefer:return=representation在Web API调用中添加标头。添加prefer标头将返回状态码200。

C＃示例

HttpClient client = new HttpClient();
client.BaseAddress = new Uri(Helpers.GetSystemUrl(APIConnector.Application.Dynamics));
client.DefaultRequestHeaders.Clear();
client.DefaultRequestHeaders.Accept.Add(new System.Net.Http.Headers.MediaTypeWithQualityHeaderValue("application/json"));
client.DefaultRequestHeaders.Add("OData-MaxVersion", "4.0");
client.DefaultRequestHeaders.Add("OData-Version", "4.0");
client.DefaultRequestHeaders.Add("prefer", "return=representation");

打字稿示例

let xhr = new XMLHttpRequest();
xhr.open("PATCH", CONNECTION_URL, true);
xhr.setRequestHeader("Accept", "application/json");
xhr.setRequestHeader("OData-MaxVersion", "4.0");
xhr.setRequestHeader("OData-Version", "4.0");
xhr.setRequestHeader("Content-Type", "application/json");          
xhr.setRequestHeader("prefer", "return=representation");