分段数据上传-Azure Function V2

问题描述

正在将文档上传到HTTP触发器Azure函数（版本2）。在函数中接收到请求后，我看到“文件”部分为空，流被移至formdata字典。下面是代码如何上载文档，有人可以帮我为什么它不填充IFormFileCollection中的流。

---

      using (var _httpClient = new HttpClient())
            {
                MultipartFormDataContent form = new MultipartFormDataContent();
                String headerValue = "form-data; name=\"file\"; filename=\"" + fileName + "\"";
                byte[] bytes = Encoding.UTF8.GetBytes(headerValue);
                headerValue = Encoding.UTF8.GetString(bytes,bytes.Length);
                fileContent.Headers.Add("Content-disposition",headerValue);
                fileContent.Headers.ContentType = MediaTypeHeaderValue.Parse("multipart/form-data");
                form.Add(fileContent);
                form.Add(new StringContent(MetadataValue),MetadataKey);
                _httpClient.Timeout = TimeSpan.FromMinutes(15);
                _httpClient.DefaultRequestHeaders.Add("Authorization","Bearer " + bearerToken);
                logger.Log@R_438_4045@ion($"HttpUtils: UploadFileByMultipart() url:{url},request param: {MetadataValue} reference: {traceLogId}");
                var response = await _httpClient.PostAsync(url,form).Result.Content.ReadAsstringAsync();
                logger.Log@R_438_4045@ion("HttpUtils: UploadFileByMultipart() end");
                return response;
            }

---

Content received in Function

其他注意事项如何从Formdata词典中获取字符串格式的流并将其转换为我可以播放的流。我在下面尝试过，结果是一个空白文档，破坏了所有流

        requestHandler.stream = new MemoryStream();
        var Content = formdata["file"].ToString();
        var fileContent = new MemoryStream(Encoding.ASCII.GetBytes(Content));

解决方法

如果我们要使用HttpClient发送多部分数据，则可以使用MultipartFormDataContent创建数据。

例如

我发送请求的代码

MultipartFormDataContent form = new MultipartFormDataContent();

            form.Add(new StringContent("jack"),"userName");

            var fileContent = new ByteArrayContent(File.ReadAllBytes(@"D:\my.csv"));

            // I use package MimeMapping : https://www.nuget.org/packages/MimeMapping/ to get file mine type
            fileContent.Headers.ContentType = new MediaTypeHeaderValue(MimeUtility.GetMimeMapping("my.csv"));
            fileContent.Headers.ContentDisposition = new ContentDispositionHeaderValue("form-data")
            {
                Name = "file",FileName = "my.csv"
            };
            form.Add(fileContent);

            using (var client = new HttpClient())
            {
                var res = await client.PostAsync("<function app url>",form);
                if (res.IsSuccessStatusCode)
                {
                    var content = await res.Content.ReadAsStringAsync();
                    Console.WriteLine(content);

                }

            }

1. 我的功能应用代码

using System.Net;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Primitives;
using Newtonsoft.Json;

public static async Task<IActionResult> Run( [HttpTrigger(AuthorizationLevel.Anonymous,"get","post",Route = null)] HttpRequest req,ILogger log)
{
            log.LogInformation("C# HTTP trigger function processed a request.");

            log.LogInformation("-------------------read file----------------------");
            // read file
            var files = req.Form.Files;
            if (files.Count != 0) {
                var file = files[0];
                
                log.LogInformation(file.ContentType);
                log.LogInformation(file.FileName);
                log.LogInformation(file.ContentDisposition);
                // use file.OpenReadStream to get a stream then use stream to rread file content

            }

            // read key

            log.LogInformation("-------------------read key----------------------");
            log.LogInformation($"The userName is {req.Form["userName"]}");

            return new OkObjectResult("OK");
}