c# - ASP.NET WebAPI : how to perform a multipart post with file upload using WebApi HttpClient

Question

我有一个 WebApi 服务处理来自简单表单的上传，如下所示:

    <form action="/api/workitems" enctype="multipart/form-data" method="post">
        <input type="hidden" name="type" value="ExtractText" />
        <input type="file" name="FileForUpload" />
        <input type="submit" value="Run test" />
    </form>

但是，我不知道如何使用 HttpClient API 模拟同一个帖子。 FormUrlEncodedContent 位很简单，但如何将文件内容与名称添加到帖子中？

Answer 1

经过反复试验，下面是实际有效的代码:

using (var client = new HttpClient())
{
    using (var content = new MultipartFormDataContent())
    {
        var values = new[]
        {
            new KeyValuePair<string, string>("Foo", "Bar"),
            new KeyValuePair<string, string>("More", "Less"),
        };

        foreach (var keyValuePair in values)
        {
            content.Add(new StringContent(keyValuePair.Value), keyValuePair.Key);
        }

        var fileContent = new ByteArrayContent(System.IO.File.ReadAllBytes(fileName));
        fileContent.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment")
        {
            FileName = "Foo.txt"
        };
        content.Add(fileContent);

        var requestUri = "/api/action";
        var result = client.PostAsync(requestUri, content).Result;
    }
}