I am working on a ASP.NET MVC website using Nhibernate as my ORM. The project is similar to a wiki/blog engine and requires that as pages are edited they store a history of the edits in another table which can then be viewed and recovered. This is complicated somewhat in that each "page" can have collections associated with it that can also be edited/added/removed. I would also need to stored these changes.
I was wondering how this fits into an entity mapping scenario such as Nhibernate and how this might be implemented. If anyone knows of any articles on this, or has done this themselves then please let me know.
I was considering triggers but I would prefer not to mix data access technologies if possible. I also am using MySql so CDC would not be possible for me.
Thanks
Either implement an auditing interceptor or use the event system. The event system is newer, I haven't found any auditing examples yet...
Also see this related question:
Take a look at NHibernate.Envers https://bitbucket.org/RogerKratz/nhibernate.envers
Related
I need to be able to save all the data that gets updated like so.
User inserts a car Model (Make, Type, Year). Comes back and Updates the Year. I need to be able to save both so they have a history of all the work that they did. What is the best way to do that?
There are a number of ways to do this. One way is to write some SQL triggers and do it entirely in the database. Have a look here for some clues:
Another way is to do the auditing within the Entity Framework code. There is a nuget package called AuditDbContext with the source on Codeplex.
You need to decide if you want to do the auditing in EF or in SQL. Obviously if you need to audit everything and you might sometimes access the database from different applications which don't use the same EF datalayer (e.g. different technologies, etc), then SQL triggers might well be the way to go.
Maybe (if you are facing the "history" issue more often) the CQRS pattern is of interest for you; a good primer, Microsoft on CQRS. There is a framework build on .NET for this pattern (I have not tried it yet): NCQRS.
If you really just want the requirement in your question fulfilled now and you are using SQL Server 2010 or later, then Change Tracking may be another option. I would prefer that to triggers (but in the end all such dark processing logging solutions introduce additional risk).
My project is in ASP.NET MVC3, SQL Server 2008 and using Fluent NHibernate.
I now have a requirement to audit certain properties of a specific object.
i.e. recording the old and new value of the properties changed on that object and also create and delete events on the object itself.
I think there can be several ways to approach this task - database triggers, INotifyPropertyChanged interface, or any NHibernate provided features?
Alternatively any open source libraries that will make my life simpler.
However, what i am not sure about is which path to choose. I mean this is a very vast area where I can go on exploring and still can't come to any conclusion.
It will be really helpful if I can get some guidance as to which option will be best considering my requirement and I can look into it more from there.
Thanks a lot.
Maybe I'm a bit biased but...
Have you had a look at Envers? https://bitbucket.org/RogerKratz/nhibernate.envers
I think its quite usual task, but still solutions I saw look not so nice.
For example in Qt used approach based on MVC pattern -- you must assign all connections manually.
Or I remember one PHP engine where pages were creating from DB schema.
Which are other approaches? Which one you are prefer? What are the best practices?
Usually, there is not a one to one mapping from the database to the GUIThere are many subtle combinations that change between how you store the data and how that stored data is visualized and edited by the user.
however, you can automate a datamodel layer in your code with tools like Hibernate. You will still need to use the model as required to present your user interface.
I'm trying to get into using Fluent NHibernate, and I have a couple questions. I'm finding the documentation to be lacking.
I understand that Fluent NHibernate / NHibernate allows you to auto-generate a database schema. Do people usually only do this for Test/Dev databases? Or is that OK to do for a production database? If it's ok for production, how do you make sure that you're not blowing away production data every time you run your app?
Once the database schema is already created, and you have production data, when new tables/columns/etc. need to be added to the Test and/or Production database, do people allow NHibernate to do this, or should this be done manually?
Is there any REALLY GOOD documentation on Fluent NHibernate? (Please don't point me to the wiki because in following along with the "Your first project" code building it myself, I was getting run-time errors because they forget to tell you to add a reference. Not cool.)
Thanks,
Andy
I've been using Fluent NHibernate Automapping for a few months now. I'm by no means an expert, but can take a stab at your questions...
FNH Automapping does indeed create DB schemas from POCO classes, including lists of other objects (this was the reason I chose NHibernate in the first place).
When you change schemas, you have to rerun the automapping, which does drop the whole database, unfortunately. In my case, it's not a big problem because I'm importing existing binary data files, so I just have to re-import my data every time the schema changes. I've read that there's some data migration support available with NHibernate, but have no experience with this. (BTW, Subsonic will do data migration, but it's automapping functionality is far more rudimentary - at least it was when I evaluated it a few months ago)
FNH documentation is one of my pet peeves - they have not even added Intellisense help on the method names, etc. (But they get really huffy when you point that out - ask me how I know!) I've made a couple of edits to the wiki when I could, but there's so much more that could be done there. The best approach is to start with a working example (i.e.
this one from Nikola Malovic, and post questions to the support form if (when!) you run into trouble. In general, I've found the FNH community pretty helpful, and have been able to work through all my difficulties. They've also fixed a couple of bugs I've found.
Overall, using FNH has been a huge win for my project - highly recommended!
I don't use Fluent, but I can help with classic NHibernate.
yes, the creation of the schema is very recommendable for production use (Schema Export). When you do this is up to you. For instance, you could create the database by an installer. You shouldn't drop existing databases, but this is a decision of you application.
I don't understand this question. Do you mean you need to upgrade an existing database to a new database schema? This is unfortunately something you need to implement yourself. NH can't do much about this, because it is very specific to you data and the changes you made. There is also a Schema Update or something like this, which is not recommended for production use.
I don't use Fluent, so I can't help here.
Do any of the available ORMs support using a bit field to represent row removal?
More information. Working in C#. I need to delete this way to support synchronization of remote database changes to a central database. I'm looking for a possible ORM, but am also interested in approaches to the problem. So if anyone knows any ORM in any language/environment that addresses this problem I would be interested in looking at it. Thanks for the questions feel free to ask more if anything is unclear.
This may not apply if you're not using .NET, but the LightSpeed ORM has a built in feature called "soft delete". Basically, when you have a DeletedOn field on your table LightSpeed will insert the time it was deleted. It automatically handles this on normal selects (e.g. where Deleted == null) so that the deleted items are not seen again. You could then write a sync process that detects the deleted state by checking that field.
You can of course instruct the querying engine to include deleted results.
Mindscape LightSpeed ORM
I am making an assumption also that we're talking about the same thing here :-)
I recommend to implement logical delete externally in your application, cause it's not very complex, but it will be more flexible. See this article for details.