CODEWITHSUNDEEP
c#linqlambdaiqueryable
Clavaat
Clavaat

Reputation: 87

IQueryable does not contain a definition for 'Select'

I'm trying to create a method that will take in a Func<Object1, bool> as a where clause and perform a Select on it as a subquery. This seems to be causing an error on the IQueryable where it cannot cast it to an expression to be parsed.

using System.Linq
using System.Data.Entity;

public IEnumerable<Object2> CreateObject2List<T> (Expression<Func<T, Object1> whereClause) 
{
    var parentQuery = (from r in dataSet.SomeObject
                       select new Object1 { Value1 = r.value1, Value2 = r.Value2 }

    var subQuery = parentQuery.Where(whereClause)
                   .Select<Object1, Object2>( o => new Object2{
        Value3 = Value1 + Value2,
        Value4 = Value1 - Value2
    })

    return subQuery.ToList();
}

The problem is occurring on the subQuery. It states:

'IQueryable' does not contain a definition for 'Select' and the best extension method overload 'Queryable.Select<Object1, Object2> (IQueryable<Object1>, Expression<Func<Object1, Object2>>)' requires a receiver of type 'IQueryable'.

I don't understand how it's not able to recognize that I've already provided an expression in the form of the lambda on the subquery. I made sure that I am using both System.Linq and System.Data.Entity. The delegate type that it is asking for is already there, so why can it not compile?

Also, for clarity, I am doing this because there are other sub-queries to be performed later, this is not a 1-to-1 snippet. I'm going for extensibility on the method call as a service.

Any help would be appreciated, and I can provide more detail as needed, thank you!

Upvotes: 2

Views: 4983

Answers (1)

Adrian Iftode
Adrian Iftode

Reputation: 15663

You most likely need

Expression<Func<Object1, bool>>

And replace .Select<Object1, Object2>( with .Select(, as mentioned in comments

Upvotes: 3

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