MongoDB for .NET with NoRM DbReference clarification

In my last post. I mentioned DbReference and how I wasn’t fond that there didn’t appear to be any way to specify that a property was in fact a reference to another document inside an implementation of MongoConfigurationMap. To be fair, this is likely not a common need when dealing with document databases and likely not needed at all for what I’m considering using a document database for, the query piece of CQRS where I will persist a view model directly as it is displayed on the screen so that no translation or multiple reads are needed. Below is a sample of the current API in NoRM for DbReference. Then to retrieve an order and it’s products.

So if you use nHibernate you’re likely seeing the same things that bother me with this API. The class Order is not POCO, and you must explicitly pass a Func<IMongo> in order to load the related products. Ideally I think the API below makes more sense and keeps things cleaner.

Then the query to eager load the related documents.

To be honest I’m not sure how difficult my proposed change would be, but I may take some time to see what it would take regardless of my current needs. I want to understand more of the internals and what a better way to understand than to contribute.

MongoDB for .NET in 10 minutes with NoRM

Technorati Tags: MongoDB,NoRM

There is a lot of talk lately in the .NET community of using a document database instead of the traditional relational database. Although I’ve kept up on the reading I haven’t invested any time trying it out for myself. Today I decided to give it a shot and considering the amount of time it took me to get things up and running I’m impressed.

First off go install MongoDB. Download Page

The install couldn’t be much simpler for me. Extract the files and run the server.

Then go download the source for NoRM and compile.

Start up a new project and begin define your class(es).

 

Then define your mapping. This step is optional it appears, however, I’m a fan of the NHibernate style of keeping persistence depedencies like identifier types, etc out of your model so I’m starting off this way.

There currently doesn’t appear to be a lot of options for mappings, mostly because there isn’t a need for lots of options. However, I would like to specify DbReference<T> in this class as well. DbReference<T> is a way to specify that the relationship of <T> is another document. Unfortunately it doesn’t appear to be supported (unless I missed something). If I get further along using NoRM this is likely something I would want to add.

Next is a sample usage of the simple model defined.

Obviously this sample isn’t ground breaking. However, I was able to download and install, compile NoRM, and put together a sample in under 10 minutes. I would say try doing that with SQL Server. The install alone takes longer than 10 minutes.

Open questions that I have that I intend to cover in the coming weeks.

• What is NoRM doing under the covers?
  
• How easy will it be to extend the behavior I described earlier when relating to other documents?
  
• How does searching against a document database change things. Can I do things like p.FirstName.StartsWith(“f”)?
  
• How well will a document database fit in with event sourcing. If it does, is it enough to have “persisted index” approach to get the current document(s) or is better to still keep that code close to the command persisting the event?
  
• Do you readers have others?