Question

I would like to create a generic update method in a ObjectContext, using a generic class. I need to loop all properties and update them based in a generic entity that i pass to my generic update method. The update method:

public void Update(T entity)
{
    if (entity == null)
    {
        throw new ArgumentNullException("entity");
    }

    var propertiesFromNewEntity = entity.GetType().GetProperties();

    // I've a method that return a entity by Id, and all my entities inherits from
    // a AbstractEntity that have a property Id.
    var currentEntity = this.SelectById(entity.Id).FirstOrDefault();

    if (currentEntity == null)
    {
        throw new ObjectNotFoundException("The entity was not found. Verify if the Id was passed properly.");
    }

    var propertiesFromCurrentEntity = currentEntity.GetType().GetProperties();

    for (int i = 0; i < propertiesFromCurrentEntity.Length; i++)
    {
        propertiesFromCurrentEntity.SetValue(propertiesFromNewEntity.GetValue(i), i);
    }
}

But this doesn’t work because the properties are passed by value, Right? So, there is a way to modify the current entity properties?

OBS: After Update, Insert and Remove methods my framework calls myContext.SaveChanges().

Answer 1

Assuming you want to set values from entity to currentEntity (otherwise, just use the reverse).

propertiesFromCurrentEntity[i].SetValue(
    currentEntity, propertiesFromNewEntity[i].GetValue(entity, null), null);