RavenDB and IDocumentStoreListener - asp.net-mvc

Question

I am trying to add an autoincrement to a simple model via an IDocumentStoreListener. I have found that the documentation regarding implementation of this feature is fairly sparse (any pointers would be greatly appreciated). I have been trying to follow this blog post but it appears to be out of date. When i try to implement
store = new EmbeddableDocumentStore
{
RunInMemory = true
}
.RegisterListener(new AuditableEntityListener(() => "Test User"))
.Initialize();
I get a build error stating "Cannot convert lambda expression to type Raven.Client.IDocumentStore because it is not a delegate type".
I managed to get it to build by using this code
store = new EmbeddableDocumentStore
{
RunInMemory = true
}
.RegisterListener(new AuditableEntityListener(store ))
.Initialize();
The code for the listener is as follows
public class PublicIdStoreListener : IDocumentStoreListener
{
HiLoKeyGenerator generator;
IDocumentStore store;
public PublicIdStoreListener(IDocumentStore store)
{
this.store = store;
generator = new HiLoKeyGenerator(store, "verifications", 1024);
}
public void AfterStore(string key, object entityInstance, RavenJObject metadata)
{
throw new NotImplementedException();
}
public bool BeforeStore(string key, object entityInstance, RavenJObject metadata)
{
var verification = entityInstance as VerifyAccountModel;
if (verification.PublicId == "0")
{
verification.PublicId = generator.GenerateDocumentKey(store.Conventions, entityInstance);
}
return false;
}
}
However, when i run the application it hits the PublicIdStoreListener when any document is stored, not just the VerifyAccountModel, which causes the application to throw an exception.
I was wondering if anyone can point me in the right direction on this as I am confused as to how this is actually supposed to be implemented. Thanks in advance.
EDIT
I updated the documentlistener to the following
public bool BeforeStore(string key, object entityInstance, RavenJObject metadata)
{
if (entityInstance.GetType() == new VerifyAccountModel().GetType())
{
var verification = entityInstance as VerifyAccountModel;
if (verification.PublicId == "0")
{
verification.PublicId = generator.GenerateDocumentKey(store.Conventions, entityInstance);
}
}
return true;
}
UPDATE
I figured out that i cant attach the store via RegisterListener in the same line that it is instantiated. It has to be done afterwards otherwise the store is still null when passed in. Thank you for your help.

Answer 1

I am not sure if there's a way to register the listener to only fire for certain types, but you can certainly structure your code to only process VerifyAccountModel entities.
var verification = entityInstance as VerifyAccountModel;
if (verification == null)
return false; // We can't do anything, just let it pass through
Also, my understanding is that you should return true when you make a change, false if no change was made. This determines whether the entity needs to be re-serialized. If that is correct, the whole thing might be restructured as follows.
var verification = entityInstance as VerifyAccountModel;
if (verification != null && verification.PublicId == "0")
{
verification.PublicId = generator.GenerateDocumentKey(store.Conventions, entityInstance);
return true; // change made, re-serialize
}
return false; // no change made