Question

A string representation of an object instance property can be taken with Expression<Func<T>>:

string propertyName = ((MemberExpression) property.Body).Member.Name;

But what if I don’t have (don’t want to create) the instance? How do I get the property name in this case?

Explained

I need a string representation of a property name of some object.

Let’s say there is an entity

public class Customer
{
    public int ID;
    public string Name;
}

Now I want to pass the key expression of this entity to some other function, thus I need the string “ID”, but I don’t want to hardcode the string like SomeOtherFunction("ID"), instead I use the expression SomeOtherFunction(ExpressionReader.GetString(() => CustomerInstance.ID)). For this to work I need to supply the entity instance.

Now I want to do the same without creating the instance.

Answer 1

This is possible with a method signature like the following:

private static string GetPropertyName<TModel, TProperty>(Expression<Func<TModel, TProperty>> property)
{
    MemberExpression memberExpression = (MemberExpression)property.Body;

    return memberExpression.Member.Name;
}

You can call this method without an instance of the customer class:

string propertyName = GetPropertyName((Customer c) => c.ID);

Of course you should add some checks for correct expression types before you cast to MemberExpression and access memberExpression.Member.Name.