Question

I am stuck on a situation where i am trying to generate password for a given username.

I am creating a username from the user’s input through textbox for FirstName and LastName, by the user’s lastname + first letter of the firstname. For e.x., If the user’s First name is ‘Ronald’ and the last name is ‘Test’, i add the username in the database as ‘Testr’. But if i had the same last name for another user and the firstname begins with the same name as existing user in the database, i add the first 2 letters of the firstname like this –

if (entities.Users.Any(a => a.LastName == tbLname.Text && a.FirstName.StartsWith(fname))) 
 username = (tbLname.Text + tbFname.Text.Substring(0,2)).ToLower();

Now the issue is, this works only if the first 2 letters match the first name. What if i had 3 or even 4 matching the first names? I dont have a clue how to check for the remaining characters to have a unique username.

Any idea on how to achieve this ?
Thanks in advance.

Answer 1

There is more information needed from the OP on this if the application wants to avoid bugs, but, in the meantime this should solve the question at hand.

//Store the first possible name.
var possibleUsername = string.Format("{0}{1}", tbLname.Text, tbFname.Text.Substring(0,1))

//Don't hit the database N times, instead get all the possible names in one shot.
var existingUsers = entities.Users.Where(u => u.Username.StartsWith(possibleUsername)).ToList();

//Find the first possible open username.
if (existingUsers.Count == 0) {
    //Create the user since the username is open.
} else {
    //Iterate through all the possible usernames and create it when a spot is open.
    for(var i = 1; i < existingUsers.Count; i++) {
        if (existingUsers.FirstOrDefault(u => u.Username == string.Format("{0}{1}", tbLname.Text, tbFname.Text.Substring(0, i))) == null) {
            //Create the user since the user name is open.
        }
    }
}