现在，您的deleteCategory()方法正在使用空的请求正文向指定的端点发出POST请求.

Right now your deleteCategory() method is making a POST request to the specified endpoint with an empty request body.

这是一个简单的示例，说明如何使用Angulars HttpClient在POST请求中包含对象数组

Here is a simple example on how to include an array of objects in a POST request using Angulars HttpClient

this.http.post('some url', JSON.stringify(yourArrayOfObjects), {headers: ...})

如果您想发送FormData(例如，如果您正在将文件上传到服务器)

If you wanted to send FormData (if for example you're uploading a file to a server)

 const frmData = new FormData();
 frmData.append("fileUpload", file)
 this.http.post('some url', frmData, {headers:...})