如何在 C# 中使用 HttpClient 发送 json 文件？

Question

I'm trying send a JSON file with postman and it's working. But when I'm trying to send the same contents via HttpClient it's not working.

System.IO.File.WriteAllText(dirName + "\\importproduct.json", jsonitems);
var fileByteArray = File.ReadAllBytes(dirName + "\\importproduct.json");

using (var _client = new HttpClient())
{
    using (var content = new MultipartFormDataContent())
    {
        content.Add(new StreamContent(new MemoryStream(fileByteArray)), "file");
        var url = $"{firmInfo.ServiceUrl}/product/api/products/import";
        _client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", bearer_token.id_token);

        var response = _client.PostAsJsonAsync(url, content).Result;
        var result = response.Content.ReadAsStringAsync().Result;
    }
}

PostMan:

Answer 1

Instead of using PostAsJsonAsync(); method you should use PostAsync(); So your code should be looking something like that

using (var _client = new HttpClient())
{
    using (var content = new MultipartFormDataContent())
    {
        content.Add(new StreamContent(new MemoryStream(fileByteArray)), "file");
        var url = $"{firmInfo.ServiceUrl}/product/api/products/import";
        _client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", bearer_token.id_token);

        var response = _client.PostAsync(url, content).Result;
        var result = response.Content.ReadAsStringAsync().Result;
    }
}

Answer 2

PostAsJsonAsync method is a generic method, it expects as the second parameter the object that will be serialized and sent in the POST body.

var obj = JsonConvert.DeserializeObject<SomeModelClass>(jsonString);
var response = await _client.PostAsJsonAsync(url, obj).Result;

Answer 3

This is based on efecetir's post above. It works for me. BTW, I also upvoted his post. My issue was I needed to set the content type at the content-based level.

var fileByteArray = File.ReadAllBytes(filePath);

HttpContent bytesContent = new ByteArrayContent(fileByteArray);
using (var httpClient = new HttpClient())
using (var formData = new MultipartFormDataContent())
{
    var RequestUri = new Uri($"http://whatever.com/");
    //client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", bearer_token.id_token);

    formData.Headers.Add("super-secret-key", "blah");
    bytesContent.Headers.ContentType = System.Net.Http.Headers.MediaTypeHeaderValue.Parse("application/json");
    
    //httpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json")); //("multipart/form-data")); // Not needed
    formData.Add(bytesContent, "file", "blah.json");
    var response = httpClient.PostAsync(RequestUri, formData).Result;
    return await HandleResponse(response);
}

Answer 4

Thanks for your comments. I fixed it and convert my codes as below. Now it's working and much more clean.

HttpContent bytesContent = new ByteArrayContent(fileByteArray);
        using (var client = new HttpClient())
        using (var formData = new MultipartFormDataContent())
        {
            var url = $"{firmInfo.ServiceUrl}/product/api/products/import";
            client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", bearer_token.id_token);

            formData.Add(bytesContent, "file", "importproduct.json");
            var response = client.PostAsync(url, formData).Result;
            var result = response.Content.ReadAsStringAsync().Result;

        }

Answer 5

Here's code I'm using to post form information and a file

using (var httpClient = new HttpClient())
{

    var surveyBytes = ConvertToByteArray(surveyResponse);


    httpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

    var byteArrayContent =   new ByteArrayContent(surveyBytes);

    byteArrayContent.Headers.ContentType = MediaTypeHeaderValue.Parse("text/csv");
       var url = $"{firmInfo.ServiceUrl}/product/api/products/import";
    var response = await httpClient.PostAsync(url , new MultipartFormDataContent
    {  
        {byteArrayContent, "\"file\"", dirName + "\\importproduct.json"}
    });

    return response;
}

This is for .net 4.5.