动态创建Expression.Lambda的通用类型

Question

I would like to create lambda expressions, type:

Expression.Lambda <Func<T,TProperty>>

but without knowing the TProperty, to save them in a collection.

public BuilderMapping<T> AutoMap()
{
    var type = typeof(T);
    var props = type.GetProperties(BindingFlags.Public);
    foreach (var propertyInfo in props)
    {
        var param = Expression.Parameter(typeof(T));
        var body = Expression.PropertyOrField(param, propertyInfo.Name);

        // propertyInfo.PropertyType == TProperty
        //  I have not TProperty
        var exp = Expression.Lambda<Func<T, TProperty>>(body, param);

        var prop = new PropertyDescriptor<T, TProperty>
        {
            Selector = exp
        };
        _descriptorColumn.Add(prop);
    }
    return this;
}

Answer 1

var delegateType = typeof(Func<,>).MakeGenericType(typeof(T), propertyInfo.PropertyType);
var exp = Expression.Lambda(delegateType, body, param);

PropertyDescriptor<T, TProperty> will need similar treatment, I think the shortest way would be this:

dynamic prop = Activator.CreateInstance(typeof(PropertyDescriptor<,>).MakeGenericType(typeof(T), propertyInfo.PropertyType));
prop.Selector = (dynamic)exp;