Expression Tree with List parameters

Question

I want to create a c# Expression Tree for the following case:

EntityA.Where(x => list.Any(y => y == x.SomeProperty))

I made a few attempts and found a few similar examples online, but nothing exactly like the above.

Any suggestions, references, solutions would be appreciated.

Answer 1

using System.Linq.Expressions;
using System.Reflection;

// example data
IQueryable<Foo> source = Enumerable.Range(0, 10)
    .Select(x => new Foo { SomeProperty = x })
    .ToList().AsQueryable();
List<int> list = [ 1, 4 ];

// expression tree construction
var any = typeof(Enumerable)
    .GetMethods(BindingFlags.Public | BindingFlags.Static)
    .Single(m => m.IsGenericMethodDefinition
              && m.Name == "Any"
              && m.GetParameters().Length == 2
           ).MakeGenericMethod(typeof(int));
var x = Expression.Parameter(typeof(Foo), "x"); // the type from "source"
var y = Expression.Parameter(typeof(int), "y"); // the type from "list"
var inner = Expression.Lambda<Func<int, bool>>(
    Expression.Equal(y, Expression.Property(x, "SomeProperty")), y);
Console.WriteLine(inner);
var outer = Expression.Lambda<Func<Foo, bool>>(
    Expression.Call(null, any, Expression.Constant(list), inner), x);
Console.WriteLine(outer);
var query = source.Where(outer);

// show it working
foreach (var item in query)
{
    Console.WriteLine(item.SomeProperty);
}
class Foo
{
    public int SomeProperty { get; set; }
}