Dynamically evaluating a property string with Expressions

Question

How do I build an expression that will fulfill the following goal:

public object Eval(object rootObj, string propertyString)

eg: Eval(pers

Answer 1

It sounds like you're looking for something like this:

public object Eval(object root, string propertyString)
{
    var propertyNames = propertyString.Split('.');
    foreach(var prop in propertyNames)
    {
        var property = root.GetType().GetProperty(prop);
        if (property == null)
        {
            throw new Exception(...);
        }

        root = property.GetValue(root, null);
    }

    return root;
}

To create an Expression use this:

public Expression Eval(object root, string propertyString)
{
    var propertyNames = propertyString.Split('.');
    ParameterExpression param = Expression.Parameter(root.GetType, "_");
    Expression property = param;
    foreach(var prop in propertyName)
    {
        property = Expression.PropertyOrField(property, prop);
    }

    return Expression.Lambda(property, param);
}