How to load document out of database instead of memory

Question

Using Raven client and server #30155. I'm basically doing the following in a controller:

public ActionResult Update(string id, EditModel model)  
{
   var store = provider.StartTransaction(false);
   var document = store.Load<T>(id);
   model.UpdateEntity(document) // overwrite document property values with those of edit model.
   document.Update(store); // tell document to update itself if it passes some conflict checking
}

Then in document.Update, I try do this:

var old = store.Load<T>(this.Id);

if (old.Date != this.Date)
{
     // Resolve conflicts that occur by moving document period
}

store.Update(this);

Now, I run into the problem that old gets loaded out of memory instead of the database and already contains the updated values. Thus, it never goes into the conflict check.

I tried working around the problem by changing the Controller.Update method into:

public ActionResult Update(string id, EditModel model)  
    {
       var store = provider.StartTransaction(false);
       var document = store.Load<T>(id);
       store.Dispose();
       model.UpdateEntity(document) // overwrite document property values with those of edit model.
       store = provider.StartTransaction(false);
       document.Update(store); // tell document to update itself if it passes some conflict checking
    }

This results in me getting a Raven.Client.Exceptions.NonUniqueObjectException with the text: Attempted to associate a different object with id

Now, the questions:

1. Why would Raven care if I try and associate a new object with the id as long as the new object carries the proper e-tag and type?

2. Is it possible to load a document in its database state (overriding default behavior to fetch document from memory if it exists there)?

3. What is a good solution to getting the document.Update() to work (preferably without having to pass the old object along)?

Answer 1

1. Why would Raven care if I try and associate a new object with the id as long as the new object carries the proper e-tag and type?

RavenDB leans on being able to serve the documents from memory (which is faster). By checking for persisting objects for the same id, hard to debug errors are prevented.

EDIT: See comment of Rayen below. If you enable concurrency checking / provide etag in the Store, you can bypass the error.

2. Is it possible to load a document in its database state (overriding default behavior to fetch document from memory if it exists there)?

Apparantly not.

3. What is a good solution to getting the document.Update() to work (preferably without having to pass the old object along)?

I went with refactoring the document.Update method to also have an optional parameter to receive the old date period, since #1 and #2 don't seem possible.

Answer 2

RavenDB supports optimistic concurrency out of the box. The only thing you need to do is to call it.

session.Advanced.UseOptimisticConcurrency = true;

See: http://ravendb.net/docs/article-page/3.5/Csharp/client-api/session/configuration/how-to-enable-optimistic-concurrency