在数据库中插入随机数的冗余-angularjs asp.net mvc

Question

I got a foreach loop in my angularjs controller

AccountController
angular.forEach($scope.accountList,function (account) {

      AccountService.insertNewAccount(account).then(function (msg)
           //some codes
      });
});

In my AccountController.cs

int accountNo = GenerateRandomNo();
var chk = db.sp_check_account_number(accountNo).ToList(); //check if there's redudancy in generated AccountNumber in Account Table
var cnt = chk.Count;
    if (cnt < 1)//If there is no redundancy
    {
        db.InsertNewAccount(name, accountNo);
    }
    else 
    {
        //if there's redundancy generate another account number
        while(cnt!=0)
        {
            accountNo = GenerateRandomNo();
            chk = db.GetROPAAccount(accountNo).ToList();
            cnt = chk.Count;
        }
        db.InsertNewAccount(name, accountNo); 
    }

    db.SaveChanges();

My insert method in AccountController.cs functioning well but the problem is when it's done inserting the data came from $scope.accountList array, the inserted AccountNumber in the table record got many redundancy. I found out that my foreach loop inserted the data randomly and I don't know why. I also check my sp_check_account_number and it's working fine. Can someone help me with this? :(

Answer 1

You problem is with the GenerateRandomNo method. Currently you have this:

public int GenerateRandomNo()
{
    int min = 1000;
    int max = 9999;
    Random rdm = new Random();
    return rdm.Next(min, max);
}

There's your problem - Random rdm = new Random(); - if that's called in rapid succession you often get the same seed value so the values aren't random. Move this line out as a class-level variable and try again.

Do this:

private Random rdm = new Random();
public int GenerateRandomNo()
{
    int min = 1000;
    int max = 9999;
    return rdm.Next(min, max);
}

Also, as an extra thing, you're generating numbers from 1000 to 9998 when you use 1000 and 9999 as your input parameters. The second parameter is an exclusive maximum value.