Session: How to Subscribe to Events

This event is invoked as a part of SaveChanges but before it is actually sent to the server.
It should be defined with this signature:

private void OnBeforeStoreEvent(object sender, BeforeStoreEventArgs args);

The class BeforeStoreEventArgs:

public class BeforeStoreEventArgs
{
    public InMemoryDocumentSessionOperations Session;
    public string DocumentId;
    public object Entity;
    public IMetadataDictionary DocumentMetadata;
}

Example

Say we want to discontinue all of the products that are not in stock.

private void OnBeforeStoreEvent(object sender, BeforeStoreEventArgs args)
{
    var product = args.Entity as Product;
    if (product?.UnitsInStock == 0)
    {
        product.Discontinued = true;
    }
}

After we subscribe to the event, every stored entity will invoke the method.

// Subscribe to the event
session.Advanced.OnBeforeStore += OnBeforeStoreEvent;

session.Store(new Product
{
    Name = "RavenDB v3.5",
    UnitsInStock = 0
});
session.Store(new Product
{
    Name = "RavenDB v4.0",
    UnitsInStock = 1000
});

session.SaveChanges(); // Here the method is invoked

This event is invoked by Delete(id) or Delete(entity). It is only executed when SaveChanges() is called, but before the commands are actually sent to the server.
It should be defined with this signature:

private void OnBeforeDeleteEvent(object sender, BeforeDeleteEventArgs args);

The class BeforeDeleteEventArgs:

public class BeforeDeleteEventArgs
{
    public InMemoryDocumentSessionOperations Session;
    public string DocumentId;
    public object Entity;
    public IMetadataDictionary DocumentMetadata;
}

Example

To prevent anyone from deleting entities we can create a method as follows:

private void OnBeforeDeleteEvent(object sender, BeforeDeleteEventArgs args)
{
    throw new NotSupportedException();
}

and subscribe it to the session:

// Subscribe to the event
session.Advanced.OnBeforeDelete += OnBeforeDeleteEvent;

var product = session.Load<Product>("products/1-A");
var product2 = session.Load<Product>("products/2-A");

// OnBeforeDelete is triggered whether you
// call Delete() on an entity or on its ID
session.Delete(product);
session.SaveChanges(); // NotSupportedException will be thrown

session.Delete("products/2-A");
session.SaveChanges(); // NotSupportedException will be thrown

This event is invoked after the SaveChanges is returned.
It should be defined with this signature:

private void OnAfterSaveChangesEvent(object sender, AfterSaveChangesEventArgs args);

The class AfterSaveChangesEventArgs:

public class AfterSaveChangesEventArgs
{
    public InMemoryDocumentSessionOperations Session;
    public string DocumentId;
    public object Entity;
}

Example

If we want to log each entity that was saved, we can create a method as follows:

private void OnAfterSaveChangesEvent(object sender, AfterSaveChangesEventArgs args)
{
    if (Log.IsInfoEnabled)
        Log.Info($"Document '{args.DocumentId}' was saved.");
}

This event is invoked just before the query is sent to the server. It should be defined with this signature:

private void OnBeforeQueryEvent(object sender, BeforeQueryEventArgs args);

The class BeforeQueryEventArgs:

public class BeforeQueryEventArgs
{
    public InMemoryDocumentSessionOperations Session;
    public IDocumentQueryCustomization queryCustomization;
}

Example I

If you want to disable caching of all query results, you can implement the method as follows:

private void OnBeforeQueryEvent(object sender, BeforeQueryEventArgs args)
{
    args.QueryCustomization.NoCaching();
}

Example II

If you want each query to wait for non-stale results you can create an event as follows:

private void OnBeforeQueryEvent(object sender, BeforeQueryEventArgs args)
{
    args.QueryCustomization.WaitForNonStaleResults(TimeSpan.FromSeconds(30));
}

This event is invoked before conversion of an entity to blittable JSON document. E.g. it's called when sending a document to a server.
It should be defined with this signature:

private void OnBeforeConversionToDocumentEvent(object sender, BeforeConversionToDocumentEventArgs args);

The class BeforeConversionToDocumentEventArgs:

public class BeforeConversionToDocumentEventArgs
{
    public InMemoryDocumentSessionOperations Session;
    public string DocumentId;
    public object Entity;
}

Example

private void OnBeforeConversionToDocument(object sender, BeforeConversionToDocumentEventArgs args)
{
    if (args.Entity is Item item)
        item.Before = true;
}

This event is invoked after conversion of an entity to blittable JSON document.
It should be defined with this signature:

private void OnAfterConversionToDocumentEvent(object sender, AfterConversionToDocumentEventArgs args);

The class AfterConversionToDocumentEventArgs:

public class AfterConversionToDocumentEventArgs
{
    public InMemoryDocumentSessionOperations Session;
    public string DocumentId;
    public object Entity;
}

Example

private void OnAfterConversionToDocument(object sender, AfterConversionToDocumentEventArgs args)
{
    if (args.Entity is Item item)
    {
        if (args.Document.Modifications == null)
            args.Document.Modifications = new DynamicJsonValue();

        args.Document.Modifications["After"] = true;
        args.Document = args.Session.Context.ReadObject(args.Document, args.Id);

        item.After = true;
    }
}

This event is invoked before conversion of a JSON document to an entity. E.g. it's called when loading a document.

It takes the argument BeforeConversionToEntityEventArgs, that consists of a JSON document, its ID and type, and the session instance.

private void OnBeforeConversionToEntity(object sender, BeforeConversionToEntityEventArgs args)
{
    var document = args.Document;
    if (document.Modifications == null)
        document.Modifications = new DynamicJsonValue();

    document.Modifications["Before"] = true;
    args.Document = args.Session.Context.ReadObject(document, args.Id);
}

This event is invoked after conversion of a JSON document to an entity. It takes the argument AfterConversionToEntityEventArgs, that consists of a JSON document, its ID, the session instance and a converted entity.

private void OnAfterConversionToEntity(object sender, AfterConversionToEntityEventArgs args)
{
    if (args.Entity is Item item)
        item.After = true;
}