Question

what is wrong in the below

Enumerable.Range(0, objEntityCode.Count - 1).Select(i => 
{ 
options.Attributes[i] = new EntityCodeKey 
{ 
EntityCode = objEntityCode[i].EntityCodes 
, OrganizationCode = Constants.ORGANIZATION_CODE }; 
})
.ToArray(); 

Throwing error The type arguments for method ‘System.Linq.Enumerable.Select(System.Collections.Generic.IEnumerable, System.Func)’ cannot be inferred from the usage. Try specifying the type arguments explicitly.

But this works

Enumerable.Range(0, objEntityCode.Count - 1).ToList().ForEach(i =>  
                { 
                    options.Attributes[i] = new EntityCodeKey 
                    { 
                         EntityCode = objEntityCode[i].EntityCodes 
                         , OrganizationCode = Constants.ORGANIZATION_CODE   
                    };  

                } 
             ); 

Using C#3.0.

Purpose: I am learning LINQ / LAMBDA and trying to do the same program in different way.

Thanks.

Answer 1

As I stated in a comment – your lambda expression doesn’t return anything. Therefore it can’t be used in a projection. Select is meant to transform a sequence of items of one type into a sequence of items of another type. You’re not doing any transforming in your lambda expression – you’ve just got an assignment.

Now you could do this:

Enumerable.Range(0, objEntityCode.Count - 1).Select(i => 
{ 
    return options.Attributes[i] = new EntityCodeKey 
    { 
        EntityCode = objEntityCode[i].EntityCodes,
        OrganizationCode = Constants.ORGANIZATION_CODE
    }; 
})
.ToArray();

I wouldn’t recommend it though. I appreciate you’re currently learning about LINQ and lambda expressions, but it’s worth learning when not to use them too – and this looks like a situation where you really, really shouldn’t use them.