[ACCEPTED]-Use reflection to make dynamic LINQ statements in C#-reflection
Accepted answer
You should use Expression Trees instead 6 of reflection. It will perform better, and 5 you'll be able to use it with both LINQ 4 to Objects and LINQ to SQL/Entities.
var source = new List<Test> { new Test { Id = 1, Name = "FirsT" }, new Test { Id = 2, Name = "Second" } };
var idName = "Id";
var idValue = 1;
var param = Expression.Parameter(typeof(Test));
var condition =
Expression.Lambda<Func<Test, bool>>(
Expression.Equal(
Expression.Property(param, idName),
Expression.Constant(idValue, typeof(int))
),
param
).Compile(); // for LINQ to SQl/Entities skip Compile() call
var item = source.SingleOrDefault(condition);
then, you 3 can get Name property using reflection (you'll 2 do it just once, so it's fine to do it using 1 reflection.
var nameName = "Name";
var name = item == null ? null : (string) typeof(Test).GetProperty(nameName).GetValue(item);
Test class is defined as
public class Test
{
public int Id { get; set; }
public string Name { get; set; }
}
You can't use reflection, but you can use 4 dynamic Linq as described here. If you are 3 using Entity Framework for this, you should 2 also be able to use Entity SQL, which is 1 basically a hard-coded SQL string.
Source:
stackoverflow.com
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