How to update Model when binding to a ViewModel?

Question

I have an [HttpPost] action method signature like this:

[HttpPost]
public ActionResult Edit(ExistingPostViewModel model)
{
   // Save the edited Pos         


        

Answer 1

For simple things where you don't have to run any controls prior to implementing the update what you are doing is okay (db.get(), and then update).

When things get complicated, you have to load the entity, and then select and apply user's changes from the view model, property by property. In those cases, you end up writing Update methods, which gets the new data as input, and then you load the existing entity, then compare states, and take the required actions based on the view model data. Actually in this case, probably you wont have an Update method but will have behaviors, like CancelPost, AddComment, EditPost (which also logs the edit reason), AddTagsToPost etc.