Creating expression tree for accessing a Generic type's property

c#, expression-trees, generics, linq

Solution

Assuming the parameter type and return type aren't known in advance, you may have to use some `object`, but fundamentally this is just:

var p = Expression.Parameter(typeof(object));
var expr = Expression.Lambda<Func<object, object>>(
    Expression.Convert(
        Expression.PropertyOrField(
             Expression.Convert(p, a.GetType()), propName), typeof(object)), p);

If the input and output types are known, you can tweak the `Func<,>` parameters, and maybe remove the `Expression.Convert`. At the extreme end you can get a lambda without knowing the signature of lambda, via:

var p = Expression.Parameter(a.GetType());
var expr = Expression.Lambda(Expression.PropertyOrField(p, propName), p);

Problem

I need to write a generic method which takes the instance of the generic type and the property name in string format and return an Expression tree I need to convert a simple lambda expression ``` a => a.SomePropertyName ``` where `a` is generic type which will have a property by the name `SomePropertyName` I know that we can get the property information using the following reflection code ``` System.Reflection.PropertyInfo propInfo = a.GetType().GetProperty("SomePropertyName"); ``` This might be very simple, but I'm not well versed with Expression trees, If there is a similar question, please link it and close this

Original source