.NET Core - How to upload JSON file? - json

Question

I am trying to upload JSON file in order to read values from it and save them in database, but I have problem with that. Code of my controller looks as following:
[Produces("application/json")]
[Route("api/[controller]")]
[ApiController]
public class ImportController : ControllerBase
{
private readonly DatabaseContext dbContext;
public ImportController(DatabaseContext dbContext)
{
this.dbContext = dbContext;
}
[HttpPost]
public IActionResult ImportData(IFormFile file)
{
var content = string.Empty;
using (var reader = new StreamReader(file.OpenReadStream()))
{
content = reader.ReadToEnd();
}
List<UserModel> userObjects = null;
try
{
userObjects = JsonConvert.DeserializeObject<List<UserModel>>(content);
}
catch
{
return BadRequest();
}
foreach (var user in userObjects)
{
UserModel us = new UserModel
{
Username = user.Username,
Password = user.Password
};
dbContext.User.Add(us);
dbContext.SaveChanges();
}
return Ok();
}
}
I'm using Postman to send JSON data, but anytime I try to do it, I get following response:
{"Username":["The input was not valid."]}
when I try to send JSON data as raw->application/json OR
{"":["The input was not valid."]}
when I try to send it by form-data with key called "file" and test.json file as value.
Could you direct me to the right path? I tried to use [FromBody] UserModel user as parameter of my action, but it only allows me to process one JSON string.

Answer 1

You can use [FromBody] IEnumerable<UserModel> users to process many rows. In this case json should look like:
[
{
"userName": "name",
"password": "password",
},
{
"userName": "name1",
"password": "password1",
}
]

Answer 2

You need to standardize your approach one way or another. If you want to accept JSON, then bind to an action param of type List<UserViewModel> with the [FromBody] attribute, and client-side, use JavaScript's FileReader to get the actual content of the upload loaded file and post the content, rather than the file.
If you want to do it by file upload, then you can keep the action as it is, but you'll need to then send your own "JSON" as a file upload as well. This can be achieved by using FormData in JavaScript and creating a Blob manually from your JSON object as a string.
Long and short, whichever path you choose, be uniform about it. There's no way to handle both posting a JSON object and a file upload that happens to be a text file with a .json extension in the same action.

Answer 3

I resolved it... All I had to do was deleting [ApiController] attribute. Having that attribute caused application to didn't visit my ImportData method at all.