将对象转换为 JSON，然后将 JSON 下载为文本文件 [Asp.net core]

Question

信息和代码：

我正在设计一个 UI，用户可以在其中设计一个对象来满足他们的需要。之后，我希望他们能够单击一个按钮来下载包含此对象的 JSON 表示的文件。单击按钮时，jquery 单击侦听器将使用 ajax 命中控制器上的端点。目前，端点如下所示：

   // GET: api/Missions/DownloadMission?id
    [HttpGet]
    [Route("api/Missions/DownloadMission{id}")]
    public IHttpActionResult DownloadMission(int id)
    {
        Mission toDownload = db.Missions.Find(id);
        string json = JsonConvert.SerializeObject(toDownload);
    }

如你所见，任务对象的Id提供给controller，并从中抓取任务。我的问题是我不知道如何将对象转换为 JSON，然后我可以将 JSON 写入文件，并提示用户下载它。

我尝试过的事情：

  using (MemoryStream stream = new MemoryStream())
    {
        using (StreamWriter writer = new StreamWriter(stream))
        {
            while(missionJson.nex)
        }
        return File(stream, "text/plain");
    }

//I tried playing around with this type of set up, but could still not get the intended results

   byte[] bytes = System.IO.File.ReadAllBytes(data);
    var output = new FileContentResult(bytes, "application/octet-stream");
    output.FileDownloadName = "download.txt";

    return output;

    Mission toDownload = db.Missions.Find(id);
    string fileName = @"~\Mission.txt";
    try
    {
        if (File.Exists(fileName))
        {
            File.Delete(fileName);
        }  
        using (FileStream fs = File.Create(fileName))
        {
            JsonSerializer serializer = new JsonSerializer();
            serializer.Converters.Add(new JavaScriptDateTimeConverter());
            serializer.NullValueHandling = NullValueHandling.Ignore;

            using (StreamWriter sw = new StreamWriter(fileName))
            using (JsonWriter writer = new JsonTextWriter(sw))
            {
                serializer.Serialize(writer, toDownload);
            }
            return File(fs, "Mission.txt");
        }   
    }
    catch (Exception Ex)
    {
        Console.WriteLine(Ex.ToString());
    }
// In this case, "File()" isnt recognized, but this is probably the closest i've been

我已经看过this one

问题：

就像我之前说的，我不知道如何从对象到 Json 再到文件
基本上我能在网上找到的所有教程都非常过时，或者需要文件路径，假设您提供的是预先存在的文件，而我不是。

Answer 1

Like I said earlier, I don't know how to go from object to Json to a file
1. 您可以使用 System.Text.Json 命名空间来序列化和反序列化 JavaScript Object Notation (JSON)。
2. string jsonString = JsonSerializer.Serialize(weatherForecast);

basically all tutorials I can find online are very outdated, or require a filepath, presuming you are providing a pre-existing file, which I am not.

您可以return FileContentResult.
您可以查看下面的示例。

代码

 [HttpGet("DownloadMission/{id}")]
 public FileContentResult DownloadMission(int id)
 {
     Mission toDownload = new Mission { Id = 1, name = "test" };
     string jsonString = JsonSerializer.Serialize(toDownload);
     var fileName = "test.txt";
     var mimeType = "text/plain";
     var fileBytes = Encoding.ASCII.GetBytes(jsonString);
     return new FileContentResult(fileBytes, mimeType)
     {
         FileDownloadName = fileName
     };
 }

结果

Answer 2

这对你有用：

[HttpGet]
[Route("api/Missions/DownloadMission{id}")]
public IHttpActionResult DownloadMission(int id)
{
    var toDownload = db.Missions.Find(id);
       
    // if you set this, the browser asks the user to save 'export.json'
    HttpContext.Response.Headers.Add("Content-Disposition", "attachment; filename=export.json");

    // return content as json with your default json serializer settings
    return new JsonResult(toDownload);
}

如前所述，将 IHttpActionResult 替换为 IActionResult，这是 ASP.NET Core 的正确 return 类型。

我没有尝试它在更大 objects 下的表现，也许需要一些优化。

或者，您也可以以更“花哨”的方式设置 header，这将正确地转义您的文件名并为您提供一些额外的属性来设置。

HttpContext.Response.Headers.Add("Content-Disposition", new System.Net.Mime.ContentDisposition
{
    FileName = "export.json",
    Inline   = false
}.ToString());

将对象转换为 JSON，然后将 JSON 下载为文本文件 [Asp.net core]

Convert an object to JSON, then download that JSON as a text file [Asp.net core]

c#

json

file

download

asp.net-core

信息和代码：

我尝试过的事情：

问题：