CODEWITHSUNDEEP
c#asp.net-mvcentity-framework
Nyprez
Nyprez

Reputation: 316

MVC - How to check if Username is not already taken?

I'm using database-first and I validating my inputs via ViewModel. However, I would like to check if either UserName is already taken in db. How do I do that? This is how far I managed to get (I can validate and save):

[Required]
[StringLength(50)]
[MinLength(3, ErrorMessage = "You must at least have 3 letters")]
public string UserName { get; set; }

And the following is my Register code in controller:

    [HttpGet]
    public ActionResult Register() {
        return View();
    }

    [HttpPost]
    public ActionResult Register(UserVIewModel reg) {
        if (ModelState.IsValid)
        {
            var m = new User {
                UserName = reg.UserName,
                Email = reg.Email,
                FirstName = reg.FirstName,
                LastName = reg.LastName,
                Password = reg.Password
            };

            db.Users.Add(m);
            db.SaveChanges();

            return RedirectToAction("Login");

        }
        return View();
    }

Upvotes: 1

Views: 4615

Answers (2)

Francisc0
Francisc0

Reputation: 1018

This will query and return the first entry in the db matching the criteria OR null db.Users.FirstOrDefault(x => x.UserName == reg.UserName)

So I would just check if that query returns a value or null and set a bool (see code below)

note the x, you can use another letter or word. maybe data => data.UserName.... or row => row.UserName... or result => result.UserName..., it just represents the Model for the db

something like this (rearranged the code a bit as well)

[HttpPost]
public ActionResult Register(UserVIewModel reg) {
    if (!ModelState.IsValid)
    {
         return View(model);
    }

    // here is the main answer to your question
    bool userExists = db.Users.FirstOrDefault(x => x.UserName == reg.UserName) != null;

    // and then use the bool to see if you need to return an error
    if (userExists) { 
        // I'm not 100% sure about this part so double-check this
        // but I think it's pretty close to this
        ModelState.AddModelError("UserName","UserName taken");
        return View(model);
    }


    // If the userExists = false then code continues here
    var m = new User {
        UserName = reg.UserName,
        Email = reg.Email,
        FirstName = reg.FirstName,
        LastName = reg.LastName,
        Password = reg.Password
    };

    db.Users.Add(m);
    db.SaveChanges();

    return RedirectToAction("Login");
}

Upvotes: 1

Cinchoo
Cinchoo

Reputation: 6322

This is how you can do check on user inside Register() method

[HttpPost]
public ActionResult Register(UserVIewModel reg) {
    if (ModelState.IsValid)
    {

        if (db.Users.Where(u => u.UserName == reg.UserName).Any())
        {
           //Do what do u need to do...
        }
        else
        {
          var m = new User {
            UserName = reg.UserName,
            Email = reg.Email,
            FirstName = reg.FirstName,
            LastName = reg.LastName,
            Password = reg.Password
          };

          db.Users.Add(m);
          db.SaveChanges();

          return RedirectToAction("Login");
        }
    }
    return View();
}

Upvotes: 5

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