Passing lambda expressions as parameters using reflection

Question

I have a generic repository method call which is as follows

var result = Repository<MyDbClass>.Get(x => x.MyProperty1 == "Something"
&& (!x.MyProperty2.HasValue || x.MyProperty2 == "SomethingElse"));

I hope to call this method using reflection. I am mainly looking for a way to pass the lambda expression as a parameter using reflection.

EDIT

Actually my repository type will be known only at runtime. The tables under all these repositories are similar having some columns in common. It is on these columns the filter is applied. So I cannot pass an expression as it is.

public void SomeMethod<T, TR>(T repository, TR dataObject)
{
    var type = repository.GetType();
    var dataType = dataObject.GetType();
    var getMethod = type.GetMethod("Get");
    //How to invoke the method by passing the lambda as parameter(??)

}

possible duplicate of How do I invoke a method through reflection with a lambda expression as a parameter? — Raphaël Althaus
– Raphaël Althaus, Commented Jan 24, 2013 at 12:29

Jan P. · Accepted Answer · 2013-01-24 13:32:39Z

1

Try passing a Func<TR, bool>

var method = typeof(TR).GetMethod("Get");

if (method != null)
{
    method.Invoke(new Func<TR, bool>(
        (x) => x.MyProperty1 == "Something" /* etc... */));
}

By assuming you use LINQ methods in your Get method, you can just fill the func in like this

public IEnumerable<TR> Get<TR>(Func<TR, bool> func)
{
    return
        db.MyDbClassEntities.Where(func);
}

edited Jan 24, 2013 at 13:32

answered Jan 24, 2013 at 12:45

Jan P.

3,29722 silver badges26 bronze badges

Sign up to request clarification or add additional context in comments.

7 Comments

Vijay Ganesh Over a year ago

I will know my repository type only at runtime. Question edited for more clarity.

Vijay Ganesh Over a year ago

Can I really form an expression like that without the compiler knowing what TR is? What is the relation between MyProperty1 and TR?

Jan P. Over a year ago

You can't archive what you want if the compile hasn't any information about the TR type. Isn't there any interface implemented by the possible types?

Vijay Ganesh Over a year ago

can't I build an expression tree using TR as I do know the properties in TR used in the expression?

Jan P. Over a year ago

You could do this, but it would be very dangerous if an unexpected type is passed to the function. Do you know all types that may be passed to the function?

|

Collectives™ on Stack Overflow

Passing lambda expressions as parameters using reflection

1 Answer 1

7 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

7 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related