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c# - C#：将模型从正文和文件作为 MultipartFormDataContent 发布

问题描述

我正在寻找一种在一个请求中发送模型和图像的方法。我试图从 body 发送我的模型，但我不知道如何发送文件。除了在不同的文件中发送图像和模型之外，还有其他方法吗？

这是我的 API 中的 POST 方法：

[HttpPost]
[Route("UploadNewEvent")]
public async Task<IActionResult> CreateNewEventAsync([FromBody] EventModel model)
{
    var file = this.Request.Form.Files.LastOrDefault();

    if (file != null)
    {
        var uploads = Path.Combine(_environment.WebRootPath, "uploads");

        using (var fileStream = new FileStream(Path.Combine(uploads, "test.jpg"), FileMode.Create))
        {
            await file.CopyToAsync(fileStream);
        }
     }

     // do sth with model later    
     return Ok();
}

这是我的应用程序中的代码：

public async Task SendNewEvent(EventModel model, MediaFile photo)
{
    var uri = $"{baseUri}api/User/Event/CreateNewEvent";

    if (photo != null)
    {
        var multipartContent = new MultipartFormDataContent();
        multipartContent.Add(new StreamContent(photo.GetStream()), "\"file\"", $"\"{photo.Path}\"");

        var httpClient = new HttpClient();               
        var jsonObject = JsonConvert.SerializeObject(model);
        var stringContent = new StringContent(jsonObject, Encoding.UTF8, "application/json");
        var httpResponseMessage = await httpClient.PostAsync(uri, stringContent);
    }
}

标签： c#asp.net-coremultipartform-data

解决方案

为了传递带有文件参数的模型，您需要将数据作为表单数据发布。

请按照以下步骤操作：

  1. 更改FromBody为FromForm

        [HttpPost]
[Route("UploadNewEvent")]
public async Task<IActionResult> CreateNewEventAsync([FromForm] EventModel model)
{
    // do sth with model later    
    return Ok();
}

  2. 更改客户端代码以发送表单数据而不是 json 字符串

        var uri = $"https://localhost:44339/UploadNewEvent";
    FileStream fileStream = new FileStream(@"filepath\T1.PNG", FileMode.Open);
    var multipartContent = new MultipartFormDataContent();
    multipartContent.Add(new StreamContent(fileStream), "\"file\"", @"filepath\T1.PNG");


    // EventModel other fields
    multipartContent.Add(new StringContent("2"), "Id");
    multipartContent.Add(new StringContent("Tom"), "Name");
    var httpClient = new HttpClient();
    var httpResponseMessage = httpClient.PostAsync(uri, multipartContent).Result;

  3. 事件模型

    public class EventModel
{
public int Id { get; set; }
public string Name { get; set; }
public IFormFile File { get; set; }
}

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