Dynamic Linq where clause with object?

Question

i'm using Dynamic Linq of Scott Gu and following this example:

Expression<Func<Customer, bool>> e1 = DynamicExpression.ParseLambda<Customer, bool>("City = \"London\"");
Expression<Func<Customer, bool>> e2 = DynamicExpression.ParseLambda<Customer, bool>("Orders.Count >= 10");
IQueryable<Customer> query = db.Customers.Where("@0(it) and @1(it)", e1, e2);

But in my case, i want to have dynamic variable of object.property in e1, e2... in where clause like this:

Expression<Func<Customer, bool>> e1 = DynamicExpression.ParseLambda<Customer, bool>("City = **[object.property]**");

i will be fill with value property of object at runtime

Can anyone please tell me how to do this?

Thanks

P/s: this can be done in case of expression:

var exp = "Person.Age = Persion1.Age";
var p = Expression.Parameter(typeof(Person), "Person");
var p1 = Expression.Parameter(typeof(Person1), "Person1");
var e = DynamicExpression.ParseLambda(new[] { p,p1 }, null, exp);
var result = e.Compile().DynamicInvoke(p,p1);

but i don't know how to do this in where clause.

Edit, as @pil0t: The answer for this case is using: Expression<Func<Customer, bool>> e1 = DynamicExpression.ParseLambda<Customer, bool>("Age > @0.Age",objPerson1);

Can I using something like Expression<Func<Customer, bool>> e1 = DynamicExpression.ParseLambda<Customer, bool>("Age > @Persion1.Age",objPerson1); intead of @0. ?

Answer 1

If you goal is to get property value by name, you could simply use reflection:

object obj = new {MyProp = 123};
var valueOfDynamicProperty = obj.GetType().GetProperty("MyProp").GetValue(obj);
Expression<Func<Customer, bool>> e1 = DynamicExpression.ParseLambda<Customer, bool>("Age = @0", valueOfDynamicProperty);

For use property name in Dynamic expression it must be declared in type that you pass in ParseLambda, so:

object obj = new {MyProp = 123};
Expression<Func<Customer, bool>> e1 = DynamicExpression.ParseLambda<Customer, bool>("Age = @0.MyProp", obj);

will not work, but you can pass specific type:

public class MyClass
{
   public int MyProperty {get;set;}
}

...

var obj = new MyClass {MyProperty = 123}; // obj is MyClass
Expression<Func<Customer, bool>> e1 = DynamicExpression.ParseLambda<Customer, bool>("Age = @0.MyProp", obj);