c# - 为什么我从 Web API Controller 上的 Post 方法得到一个空值？

Question

我有一个非常简单的 WebAPI 类，它为我的 Get 方法返回 JSON。我的发布方法是:

    // POST: api/Diff
    public void Post([FromBody]string value)
    {
        System.Diagnostics.Debug.WriteLine(value);
    }

我正在从控制台应用程序调用这两种方法:

        using (var client = new HttpClient())
        {
            // New code:
            client.BaseAddress = new Uri("http://localhost:50541/");
            client.DefaultRequestHeaders.Accept.Clear();
            client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

            // New code:
            HttpResponseMessage response = await client.GetAsync("api/diff/1");
            if (response.IsSuccessStatusCode)
            {
                var diff = await response.Content.ReadAsAsync<Diff>();
                Console.WriteLine("{0}\t${1}", diff.Text, diff.Revision);
            }

            var blah = new Diff() { Text = "Gizmo", Revision = 999};
            response = await client.PostAsJsonAsync("api/diff", blah);

Get 调用有效。我在调试器中验证了 调用 PostAsJson 方法时 blah 不为空。然而，在 API 的 post 方法的调试器中，value 为 null。

Answer 1

该方法需要一个字符串:

public void Post([FromBody]string value)

然后您向它发送一个Diff:

var blah = new Diff() { Text = "Gizmo", Revision = 999};
response = await client.PostAsJsonAsync("api/diff", blah);

所以...

要么改变它以期待一个Diff:

public void Post([FromBody]Diff value)

或者给它发送一个字符串:

response = await client.PostAsJsonAsync("api/diff", new { value = "some string" });