How to return a file path to the controller to parse a JSON file

Question

I have a very simple view that will prompt a user to select a JSON file and then parse it.

Here is the relevant code from the view...

@using (Html.BeginForm("AddSampleDataJSON", "Event"))
{
   <input type="file" name="GetJSONFile" /><br>
   <input type="submit" />
}

Here is the method from the controller:

  [HttpPost]
  public ActionResult AddSampleDataJSON(FormCollection form)
  {
        string path = ??
        using (StreamReader r = new StreamReader(path))
         {
            string json = r.ReadToEnd();
            List<Event> events = 
            JsonConvert.DeserializeObject<List<Event>>(json);
         }
         return View();
  }

The question then is how do I access the full path so I can send it to the StreamReader to eventually parse the JSON. I don't see it in the FormCollection object.

You cant for security reasons (a browser only sends the file name and does not expose a uses file system). You parameter needs to be HttpPostedFileBase GetJSONFile and it will be populated with the file contents. And you need to set the enctype = "multipart/form-data" attribute in the form tag — user3559349
– user3559349, Commented Jun 13, 2017 at 0:16
As a parameter going into the method? It comes in as null even after I added that attribute. And the file I'm choosing is indeed a JSON file. — user1327418
– user1327418, Commented Jun 13, 2017 at 0:27
Then you did not set it correctly. (and it makes no difference what type of file it is) — user3559349
– user3559349, Commented Jun 13, 2017 at 0:28
I had to match the name of the element in the view with the variable name. Now it works! — user1327418
– user1327418, Commented Jun 13, 2017 at 1:02

Maria Ines Parnisari · Accepted Answer · 2017-06-13 00:41:26Z

2

You won't be able to access the client path to the file. You'll only see the file name.

You should set the encoding to multipart/form-data in your view:

@using (Html.BeginForm("AddSampleDataJSON", "Event", FormMethod.Post, new { enctype = "multipart/form-data" }))
{
     <input type="file" name="uploadedFile" /><br>
     <input type="submit" />
}

And in your controller change your input parameter to HttpPostedFileBase, with the parameter name being the same as the name parameter in the form:

[HttpPost]
public ActionResult AddSampleDataJSON(HttpPostedFileBase uploadedFile)
{
    using (StreamReader r = new StreamReader(uploadedFile.InputStream))
    {
        string json = r.ReadToEnd();
        List<Event> events = JsonConvert.DeserializeObject<List<Event>>(json);
    }

    return View();
}

answered Jun 13, 2017 at 0:41

Maria Ines Parnisari

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