Entity Framework 4 / POCO
I've been programming for a while and have used LINQ-To-SQL and LINQ-To-Entities before (although when using entities it has been on a Entity/Table 1-1 relationship - ie not much different than L2SQL)
I've been doing a lot of reading about Inversion of Control, Unit of Work, POCO and repository patterns and would like to use this methodology in my new applications.
Where I'm struggling is finding a clear, concise beginners guide for EF4 which doesn't assume knowledge of EF1.
The specific questions I need answered are:
Code first / model first? Pros/cons in regards to EF4 (ie what happens if I do code first, change the code at a later date and need to regenerate my DB model - Does the data get preserved and transformed or dropped?)
Assuming I'm going code-first (I'd like to see how EF4 converts that to a DB schema) how do I actually get started? Quite often I've seen articles with entity diagrams stating "So this is my entity model, now I'm going to ..." - Unfortunately, I'm unclear if they're created the model in the designer, saved it to generate code then stopped any further auto-code generation -or- They've coded (POCO)? classes and the somehow imported them into the deisgner view?
I suppose what I really need is an understanding of where the "magic" comes from and how to add it myself if I'm not just generating an EF model directly from a DB.
I'm aware the question is a little vague but I don't know what I don't know - So any input / correction / clarification appreciated.
Needless to say, I don't expect anyone to sit here and teach me EF - I'd just like some good tutorials/forums/blogs/etc. for complete entity newbies
These articles might be of interest...the series really gets into the advantages and disadvantages of a POCO approach.
http://blogs.msdn.com/b/adonet/archive/2009/05/21/poco-in-the-entity-framework-part-1-the-experience.aspx
http://blogs.msdn.com/b/adonet/archive/2009/05/28/poco-in-the-entity-framework-part-2-complex-types-deferred-loading-and-explicit-loading.aspx
http://blogs.msdn.com/b/adonet/archive/2009/06/10/poco-in-the-entity-framework-part-3-change-tracking-with-poco.aspx
In these articles the author mentions future articles that describe best practices in implementing Repository and Unit of Work patterns, but I can't find them. These articles are well written and I'd like to read more from this author.
I've come across this: http://blogs.msdn.com/adonet/pages/feature-ctp-walkthrough-code-only-for-the-entity-framework.aspx
Which gives you step-by-step for code first. It does require the CTP 3 for EF4 (Download linked from that article).
This is pretty close to what I was after (although ideally a solution that doesn't rely on a CTP would've been preferable)
I do recommend that you take a half hour or so and generate a stable EF1.0 model in your current VS. That will get you a long way towards understanding the metaphors and concepts of EF 4.0. Just whip up a simple Customer, Products and Orders db...I recommend doing your own and not using Northwind.
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