Question

I have linq query as follows:

var result = (from Customer cust in db select new { userNameList = cust.UserName }).ToList();

i want to loop through each value in the list<>

I tried to use the foreach to accomplish this. It is stupid i could not figure it out

I’m using something like this

foreach (List<string> item in result)
            {
                if (item.ToString() == userName)
                {
                    userExistsFlag = 1;
                }
            }

But the .net compiler is just freaking out:

and giving me these errors

1. Cannot implicitly convert type ‘System.Collections.Generic.List’ to ‘System.Collections.Generic.List’

2. Cannot convert type ‘AnonymousType#1’ to ‘System.Collections.Generic.List’

Thanks in anticipation

OF ALL THESE IMPLEMENTATIONS WHICH ONE IS MOST EFFICIENT AND CONSUMES LESS RESOURCES.
IT WOULD BE KIND ENOUGH IF SOME ONE CAN CLARIFY THIS FOR ME.

Answer 1

Shorter using Linq:

bool userExistsFlag  = result.Any( x=> x.userNameList  == userName);

As suggested in the other answers you do not need to project to an anonymous type:

var userNames = (from Customer cust in db select cust.UserName).ToList();
bool userExists = userNames.Contains(userName);

Edit:

The most efficient – if you do not need the set of user names otherwise – is to query the DB directly to check whether the user name exists, so

 bool userExists = db.Any( x => x.UserName == userName);

Credit goes to @Chris Shaffer in the comments and @Cybernatet’s answer – he was almost there. I would suggest you accept his answer but use Any() 😉