Migration of data stored in RavenDB

.net, ravendb

Solution

My current solution is copying current entities to temporary ones, changing desired properties, storing such new entities in database, and finally removing old ones:

using (var session = _store.OpenSession())
{
    var users = session.Query<User>().ToList();
    foreach (var user in users)
    {
        var newuser = new User
                          {
                              Id = user.Email,
                              DisplayName = user.DisplayName
                          };

        session.Store(newuser);
        session.Delete(user);
    }
    session.SaveChanges();
}

Problem

I have entities stored in RavenDB (build #888). I need to change theirs IDs, because of database migration, connected with newer version of the application. I've written sample function I'm using: ``` public bool Migrate() { using (var session = _store.OpenSession()) { var users = session.Query<User>().ToList(); foreach (var user in users) { user.Id = user.Email; } session.SaveChanges(); } } ``` Execution of this code results in an exception: ``` Status: System.InvalidOperationException: Entity App.Models.Entities.User had document key 'mydomain-mylogin' but now has document key property 'mylogin@yahoo.com'. You cannot change the document key property of a entity loaded into the session at Raven.Client.Document.InMemoryDocumentSessionOperations.CreatePutEntityCommand(Object entity, DocumentMetadata documentMetadata) at Raven.Client.Document.InMemoryDocumentSessionOperations.PrepareForEntitiesPuts(SaveChangesData result) at Raven.Client.Document.InMemoryDocumentSessionOperations.PrepareForSaveChanges() at Raven.Client.Document.DocumentSession.SaveChanges() ``` How can it be done ?

Original source