如何在C＃中将json数据转换为对象？

Question

When I convert the json file data to object I get the exception below. How do I resolve?

Unhandled Exception: Newtonsoft.Json.JsonSerializationException: Cannot deserialize the current JSON array (eg [1,2,3]) into type 'ChattingApp.API.Models.User' because the type requires a JSON object (eg {"name":"value"}) to deserialize correctly.

Here is my Code...

using System.Collections.Generic;
using ChattingApp.API.Models;


namespace ChattingApp.API.Data
{
    public class Seed
    {
        private readonly DataContext _context;
        public Seed(DataContext context)
        {
            _context = context;

        }

        public void SeedUsers()
        {
            var userData = System.IO.File.ReadAllText("Data/UserSeedData.json");

            var users = Newtonsoft.Json.JsonConvert.DeserializeObject<List<User>>(userData);
            foreach (var user in users)
            {
                byte[] passwordHash, passwordSalt;
                CreatePasswordHash("password", out passwordHash, out passwordSalt);

                user.PasswordHash = passwordHash;
                user.PasswordSalt = passwordSalt;
                user.Username = user.Username.ToLower();

                _context.Users.Add(user);
            }
            _context.SaveChanges();
        }

        private void CreatePasswordHash(string password, out byte[] passwordHash, out byte[] passwordSalt)
        {
            using(var hmac =new System.Security.Cryptography.HMACSHA512())
            {

                passwordSalt=hmac.Key;
                passwordHash=hmac.ComputeHash(System.Text.Encoding.UTF8.GetBytes(password));

            }

        }
    }
}

Answer 1

It appears that the JSON within the .json file is invalid. Given that you are expecting a list of 'Users' to be returned I would expect the JSON to be formatted like this :

[
{"Username": "Cooper", 
"Gender": "male", 
"DateOfBirth": "1980-01-21", 
"Password": "password", 
"KnownAs": "Cooper", 
"Created": "2017-04-15"}, 

{"Username": "Blyth", 
"Gender": "male", 
"DateOfBirth": "1986-06-10", 
"Password": "password213", 
"KnownAs": "SomeDude", 
"Created": "2016-02-08"}
]

You can also use https://jsonlint.com/ to validate your json.