Hi, Is it available on some public repo somewhere?
/Roger From: [email protected] [mailto:[email protected]] On Behalf Of Peter Schojer Sent: den 18 december 2015 09:29 To: nhibernate-development <[email protected]> Subject: [nhibernate-development] Re: Envers.Linq (and HQL+ full Criteria support): First prototype Newest Version: - now rewrite SQL queries work properly - bug with parameter resolving was fixed - ValidityAuditStrategy is now supported (in terms of read performance way faster than defaultauditstrategy, simply try a query with at least three joins and take a look at the rewritten query). Proxies are still not supported though, so always a use a converter/ResultTransformer. To get started check the testsuite. Edit Globals.cs to use either default or validity strategy, and update your db connection. best regards, Peter Am Mittwoch, 30. September 2015 13:17:11 UTC+2 schrieb Peter Schojer: I recently started a project to extend Envers with common Nhibernate querying functionality like HQL, Criteria or linq. The goal is to make querying between history and current as transparent and easy as possible. The current implementation is nowhere complete but with a few days of work I am already able to use HQL, Criteria and Linq to query Envers. To make further progress and overcome some of the shortcomings I could need some help though :-) Linq Query example: var query = Session.Query<User>().Where(x => x.Name == User1Version2Name && x.Addresses.Count > 0).ToList(1); For Linq I added a ToList(int versionNumber) extension method. Providing a versionNumber lower equal 0 executes queries against the current tables, otherwise AuditTables are queried. Nice and simple. No need to write queries twice for Envers and Nhibernate. Similar overloads exist for Criteria and HQL (QueryOver not done yet): var query = Session.CreateCriteria<User>().Add(Restrictions.Eq("Name", "test")).List<User>(1); var query = Session.CreateQuery("Select Id from User where Name = :name").SetParameter("name", User1Version2Name).List<int>(1); How does it work: The current implementation uses an interceptor to rewrite the generated sql from current tables to audit tables. Biggest advantage: - simple and easy to implement, no need to write own Linq provider - makes use of Nhibernates Linq provider, benefits from any future work/bugfix done there Biggest disadvantage: - executed SQL and returned data types (object + proxies!) do not match the data types from the expression tree Take this Query example: Session.Query<User>().Where(x => x.Name == "name2" && x.Addresses.Count > 0).ToList(1); We build up an expression tree for table User. In reality we are returning an AuditUser object with Version=1 (Version is part of the key). Those two types are unrelated (and also all proxy types created when evaluating a record). I am currently searching for a way to fix that. First idea, an expression tree visitor rewriting data types. This type information could be parsed from Envers (?) but I donot know enough about Envers. Are types dynamically generated at startup? Or does envers simple uses a generic type containing two properties: RevisionInfo Rev, TObject Obj. That would make rewriting the query impossible. Also dynamically changing the types after the SQL was generated is (I think) not possible for interceptors. Or maybe somehow intercept proxy/object generation? As a workaround, I have some ugly reflection hacks in place which guarantee that returned objects/created proxies are never cached in a session. So all version queries behave as if they are executed on a stateless session (try to access a proxy object -> exception). This at least prevents errors due to caching. But I'd really prefer to get rid of those hacks :-) SourceCode is attached. VS2013 project. Just let Nuget restore the packages, then adapt your connectionString in Setup/Globals.cs and see unit tests for example usage. best regards, Peter -- --- You received this message because you are subscribed to the Google Groups "nhibernate-development" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]<mailto:[email protected]>. For more options, visit https://groups.google.com/d/optout. -- --- You received this message because you are subscribed to the Google Groups "nhibernate-development" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
