Question

We have an object

public class SomeObject
{
   public Name {get;set;}
   public City {get;set;}
   public State {get;set}
   //various other parameters.  Let's say there's ~20
}

Is it possible to dynamically create new LINQ queries without recompilation of source code? Instead, the query parameters come from an XML structure that is stored and updated in the database.

var result = from i in someObj
             where 
             //XML requests Name = 'Bob'...so append this where clause
             name = 'Bob'

Can this be done?

Answer 1

Here is a solution with expression trees:

var param = Expression.Parameter(typeof(SomeObject), "p");
var exp = Expression.Lambda<Func<SomeObject, bool>>(
    Expression.Equal(
        Expression.Property(param, "Name"),
        Expression.Constant("Bob")
    ),
    param
);
var query = someObj.Where(exp);

I know it’s much more complex, but this may be useful in times.