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how to return false if no records exist in table

Anonymous User 1706 05-Dec-2014

Want to check if any records exist in ClientAccessCode table, if not return false... 

if (!CheckAccessCodeExists())
{
   
Console.WriteLine("Client Access code does not exist");
    throw new ConfigurationErrorsException("Client Access code does not exist");
} 
private static bool CheckAccessCodeExists()
{
    using (EPOSEntities db = new EPOSEntities())
    {
       
ClientAccountAccess clientAccess = db.ClientAccountAccesses
                .OrderByDescending(x => x.Id)               
.Take(1)               
.Single();
 
        if(clientAccess != null)
        {
            return true;
        }
        return false;
    }
}

//this is flagging sequence contains no elements, in the lamba expression, so how can I just return false then? some use of .Any() perhaps?

 

Thanks

asp.net c# 
Updated on 05-Dec-2014
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2 Answers

Barbara Jones

Barbara Jones

05-Dec-2014 
private static bool CheckAccessCodeExists()
    {
        using(EPOSEntities db = new EPOSEntities())
        {
            var item =db.ClientAccountAccesses.FirstOrDefault();
            if(item !=null)
            {
              
       db.Remove(item);
              
        db.SaveChanges(); 
               return true;                 
            }
 
            return false;
        }
    }

Anonymous User

Anonymous User

05-Dec-2014

The problem is Single expects there to be at least one item in the collection, if it doesn't find 1 then it throws an exception. If it's possible for your collection to not have a record then you should be using SingleOrDefault - this will return the default value for the type you are working with, in your case this will return null. 

ClientAccountAccess clientAccess = db.ClientAccountAccesses
    .OrderByDescending(x=> x.Id)
    .Take(1)  
.SingleOrDefault();
 
if (clientAccess != null)
{
   
db.DeleteObject(clientAccess);
}

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