LINQ Expression for Contains

Question

I want to add dynamic expression in linq but facing issues on contains method it is working perfectly for Equal method

Problem is i\'m getting FilterField

Answer 1

This will work for you:

void Main()
{
    var filterField = "Id";
    List<int> Ids = new List<int>();
    var eParam = Expression.Parameter(typeof(EmployeeDetail), "e");
    var method = Ids.GetType().GetMethod("Contains");
    var call = Expression.Call(Expression.Constant(Ids), method, Expression.Property(eParam, filterField));
    var lambda = Expression.Lambda<Func<EmployeeDetail, bool>>(call, eParam);
}

public class EmployeeDetail
{
    public int Id { get; set; }
}

First, you look for the Contains method on the type of Ids. Then we simply invoke it with Ids as the instance, and the property as the argument