使用C# WebRequest调用Voxbone REST API上传文件遇500错误求助

Let's break down the issues in your code that are likely causing the request to fail before reaching Voxbone's system, and walk through fixes step by step.

Key Issues in Your Current Code #

• Incorrect Boundary Format: Your ContentType includes an unnecessary space after boundary=, and the boundary string in your multipart body doesn't follow proper formatting rules. Multipart boundaries must be consistent between the header and body with no extra spaces.
• Invalid Multipart Structure: The multipart sections are missing required line breaks between the boundary, headers, and content. Voxbone's API expects strict multipart/form-data formatting, which requires empty lines to separate headers from their corresponding content.
• File Handling Mistake: You're treating the file content as a plain string ("Wuppertal") instead of reading the actual binary file content. Additionally, converting the entire multipart body to Base64 is unnecessary—you should write raw bytes directly to the request stream.
• Variable Mismatch: You define buffer3 but try to write data to the stream, which is an undefined variable, leading to a runtime error before the request even sends.

Corrected Code Example #

Here's a revised version of your code that fixes these issues and properly constructs the multipart request:

using System;
using System.IO;
using System.Net;
using System.Text;

class VoxboneAddressUpload
{
    static void Main(string[] args)
    {
        string apiUrl = "https://sandbox.voxbone.com/ws-voxbone/services/rest/regulation/address";
        string method = "POST"; // Confirm this matches Voxbone's API requirements
        string boundary = $"----VoxboneFormBoundary{DateTime.Now.Ticks.ToString("x")}"; // Unique boundary to avoid conflicts

        // Initialize web request
        WebRequest myReq = WebRequest.Create(apiUrl);
        myReq.Method = method;
        myReq.ContentType = $"multipart/form-data; boundary={boundary}";

        // Basic Authentication setup
        string username = "xxxxxx";
        string password = "xxxxxx";
        string authToken = Convert.ToBase64String(Encoding.UTF8.GetBytes($"{username}:{password}"));
        myReq.Headers.Add("Authorization", $"Basic {authToken}");

        // Build and write multipart content to request stream
        using (var reqStream = myReq.GetRequestStream())
        {
            // 1. Add JSON payload section
            string jsonPayload = @"
            {
                ""salutation"" : ""MR"",
                ""companyName"" : null,
                ""companyDescription"" : null,
                ""firstName"" : ""rahul"",
                ""lastName"" : ""singh"",
                ""buildingNumber"" : ""23"",
                ""identityDocumentProof"" : {
                    ""Nationality"" : ""IND"",
                    ""identityDocumentType"" : ""NATIONAL_ID_CARD"",
                    ""identityDocumentNumber"" : ""jfklajfljsdfl;dslfj"",
                    ""issuingAuthority"" : ""jkhkjhkj"",
                    ""issuingDate"" : ""2017-11-30""
                },
                ""extraFields"" : {
                    ""Signatory date of birth"" : ""1993-01-05"",
                    ""Signatory place of birth"" : ""varanasi,India"",
                    ""Signatory tax code"" : ""dsdfsfsdf""
                }
            }";

            byte[] jsonBytes = Encoding.UTF8.GetBytes(
                $"--{boundary}\r\n" +
                "Content-ID: createRegulationAddressRequest\r\n" +
                "Content-Type: application/json\r\n\r\n" + // Empty line separates headers from content
                jsonPayload + "\r\n"
            );
            reqStream.Write(jsonBytes, 0, jsonBytes.Length);

            // 2. Add file upload section (proofOfIdentityDocument)
            string filePath = @"C:\path\to\your\stripe.png"; // Replace with your actual file path
            if (File.Exists(filePath))
            {
                byte[] fileContent = File.ReadAllBytes(filePath);
                byte[] fileHeader = Encoding.UTF8.GetBytes(
                    $"--{boundary}\r\n" +
                    "Content-ID: proofOfIdentityDocument\r\n" +
                    "Content-Type: application/octet-stream\r\n" +
                    "Content-Transfer-Encoding: binary\r\n" +
                    $"Content-Disposition: file-data; name=\"proofOfIdentityDocument\"; filename=\"{Path.GetFileName(filePath)}\"\r\n\r\n"
                );
                reqStream.Write(fileHeader, 0, fileHeader.Length);
                reqStream.Write(fileContent, 0, fileContent.Length);
                reqStream.Write(Encoding.UTF8.GetBytes("\r\n"), 0, 2);
            }
            else
            {
                throw new FileNotFoundException("Identity proof file not found.", filePath);
            }

            // Close the multipart request with final boundary
            byte[] endBoundary = Encoding.UTF8.GetBytes($"--{boundary}--\r\n");
            reqStream.Write(endBoundary, 0, endBoundary.Length);
        }

        // Handle response and errors
        try
        {
            using (WebResponse wr = myReq.GetResponse())
            using (Stream receiveStream = wr.GetResponseStream())
            using (StreamReader reader = new StreamReader(receiveStream, Encoding.UTF8))
            {
                string content = reader.ReadToEnd();
                Console.WriteLine("API Response: " + content);
            }
        }
        catch (WebException ex)
        {
            if (ex.Response is HttpWebResponse errorResp)
            {
                Console.WriteLine($"Error Status: {(int)errorResp.StatusCode} - {errorResp.StatusDescription}");
                using (StreamReader errorReader = new StreamReader(errorResp.GetResponseStream()))
                {
                    Console.WriteLine("Error Details: " + errorReader.ReadToEnd());
                }
            }
            else
            {
                Console.WriteLine("Request failed: " + ex.Message);
            }
        }
    }
}

Additional Troubleshooting Steps #

• Confirm HTTP Method: Double-check Voxbone's API documentation to ensure you're using the correct method (most upload endpoints use POST).
• Validate JSON Schema: Ensure your JSON payload matches all required fields and data types specified in Voxbone's regulation API docs.
• Test with Postman: Replicate the request in Postman first to confirm the API works with a properly formatted request, then mirror that structure in your code.
• Enable Request Logging: Add logging to capture the full request headers and body (redact sensitive data) to verify the multipart structure is correct.

内容的提问来源于stack exchange，提问作者Rahul Singh