Validation message displayed on page load

Question

I am new to ASP.NET MVC framework, starting my first project. I've used data annotations in my model class for setting validation message. But the validation messages are shown on page load. I want the validation message to be displayed on button click. How can I do this?

Model:

using System.ComponentModel;
using System.ComponentModel.DataAnnotations;

namespace final_1.Models
{
    using System;
    using System.Collections.Generic;

    public partial class TBL_USER
    {
        public int USERID { get; set; }
        [Required(ErrorMessage = "Please enter user name.")]
        public string USERNAME { get; set; }
        public string NAME { get; set; }
        public int ROLE { get; set; }
        [Required(ErrorMessage = "Please enter password.")]
        public string PASSWORD { get; set; }
        public System.DateTime CREATED_DATE { get; set; }
        public int STATUS { get; set; }
    }
}

View:

@using (Html.BeginForm("Authorize", "Login", FormMethod.Post, new { @class = "form-horizontal", role = "form" }))
{
    @Html.AntiForgeryToken()
    @Html.ValidationSummary(true, "", new { @class = "text-danger" })
    <div class="form-group has-feedback">
        @Html.TextBoxFor(m => m.USERNAME, new { @class = "form-control", @placeholder = "User name", @autofocus = "autofocus" })
        @Html.ValidationMessageFor(m => m.USERNAME, "", new { @class = "text-danger" })
        <span class="glyphicon glyphicon-user form-control-feedback"></span>
    </div>
    <div class="form-group has-feedback">
        @Html.PasswordFor(m => m.PASSWORD, new { @class = "form-control", @placeholder = "Password" })
        @Html.ValidationMessageFor(m => m.PASSWORD, "", new { @class = "text-danger" })
        <span class="glyphicon glyphicon-lock form-control-feedback"></span>
    </div>
    <div class="row">
        <div class="col-xs-8"></div>
        <div class="col-xs-4">
            <button type="submit" class="btn btn-primary btn-block btn-flat">Sign In</button>
        </div>
    </div>
}

Controller:

public ActionResult Authorize(TBL_USER userModel)
{
    using (MIEntities db = new MIEntities())
    {
        var userDetails = db.TBL_USER.Where(a => a.USERNAME == userModel.USERNAME && a.PASSWORD == userModel.PASSWORD).FirstOrDefault();
        if (userDetails != null)
        {
            return RedirectToAction("Register", "Student");
        }
        else
        { return View(); }
    }
}

Answer 1

I created two action methods for get request and for post request.

[HttpGet] 
        public ActionResult Authorize()
        {
            return View();
        }
        [HttpPost] 
        public ActionResult Authorize(final.Models.TBL_USER userModel)
        {
            using (LT_LGCDP_MISEntities1 db = new LT_LGCDP_MISEntities1())
            {
                var userDetails = db.TBL_USER.Where(a => a.USERNAME == userModel.USERNAME && a.PASSWORD == userModel.PASSWORD).FirstOrDefault();
                if(userDetails == null)
                {
                    return View(userModel);
                }
                    return RedirectToAction("Register", "Student");
            }
        }

It worked!