使用Azure DevOps REST API添加工作项评论遇415错误求助

Let's break down why you're hitting that 415 error and fix it step by step:

The Root Cause #

Your code has two key mismatches with the Azure DevOps REST API requirements for the 5.1-preview.3 comments endpoint:

• Wrong Content-Type: You're using application/json-patch+json (this is meant for PATCH requests to update work item fields, not POST requests to add comments).
• Incorrect Request Body Format: The endpoint expects a single comment object, not an array of comments.

Corrected Code #

Here's the adjusted version of your code that should resolve the issue:

public class Comment 
{ 
    [JsonProperty("text")] 
    public string Text { get; set; } 
}

// Create a single comment object instead of wrapping it in a list
var comment = new Comment() { Text = "Test Comment" };
var body = JsonConvert.SerializeObject(comment);

// Use "application/json" as the content type (matches API expectations for POST)
var postValue = new StringContent(body, Encoding.UTF8, "application/json");

using (HttpClient httpClient = new HttpClient())
{
    httpClient.DefaultRequestHeaders.Accept.Clear();
    httpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
    httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Basic", Convert.ToBase64String(ASCIIEncoding.ASCII.GetBytes(string.Format("{0}:{1}", "", _token))));

    // Use async/await instead of .Result for non-blocking calls (best practice)
    using (HttpRequestMessage httpRequestMessage = new HttpRequestMessage(HttpMethod.Post, _apiUrl) { Content = postValue })
    {
        var httpResponseMessage = await httpClient.SendAsync(httpRequestMessage);
        // Add this to throw an exception if the request fails (helps with debugging)
        httpResponseMessage.EnsureSuccessStatusCode();
    }
}

Key Changes Explained #

1. Content-Type Fix: Switched from application/json-patch+json to application/json — this aligns with what the API expects for POST requests to create comments.
2. Request Body Fix: Removed the List<Comment> wrapper and serialized just the single Comment object. The API doesn't accept an array here, which was contributing to the invalid request format.
3. Async/Await Update: Replaced .Result with await (ensure your containing method is marked async) to avoid blocking calls, which is a standard best practice for HttpClient usage.

Additional Checks #

• Double-check that your _apiUrl follows the correct pattern: https://dev.azure.com/{org}/{proj}/_apis/wit/workItems/{id}/comments?api-version=5.1-preview.3
• Confirm your personal access token (_token) has the Work Items (Read & Write) permission scoped to the target project.

内容的提问来源于stack exchange，提问作者Nitin Manju