DotNetRocks #169, Second Take: O/RM
time to read 2 min | 279 words

I listened to the rest of the DotNetRocks episode 169 with Rocky Lhotka. This time, I wanted to comment about the part where Rocky talks about ORM. Before everything else, I would like to comment on something he said about Microsoft and O/RM.

He said that most O/RM are using Reflection, and that only Microsoft can solve this issue, because the can modify the CLR to allow direct access to private fields.

I wanted to note that there is already such a thing in .Net 2.0, and it is called LCG (Lightwieght Code Generation), and it basically means that you can inject a method into a class, which will have full access to all the class' members, regardless of visibility (just as any class on the object does). There is a patch for NHibernate that allows it to use this functionality in .Net 2.0, so you don't need to me Microsoft to use this.

I would also like to comment that NHibernte is already avoiding Reflection whenever possible, relying on runtime code generation to read and write to public properties / fields. 

I want to address another part of what he said, where he said that O/RM assumes that objects are structure the same way as the database is. Only the simplest O/RM assumes this. One of the important charactaristics of objects is not the data they contain, but what type of object you have, and what relations it has to other objects. A good O/RM will know to map the schema of a database to your object structure without impacting the design of the object.

In fact, I would go as far as to say that this is the criteria of good O/RM.

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