Tuesday, 5 May 2009

LINQ to SQL only goes so far.

I have just finished re-writing my ailing photography website. I have taken the opportunity to write it afresh using ASP.Net MVC and LINQ to SQL. Whilst the latter is hugely more sensible than programming against a database it did highlight a flaw quite early on.

'Entities' in LINQ to SQL (i.e. database tables / views) are connected to each other via Associations. These map 1-1 with the Relationships in your database. Unfortunately, you can't customise these objects thus denying the developer and means to filter entities. Example:

I have 2 main entities in my application: Albums and Photos. An Album can contain many Photos and a Photo must be part of one, and only one, Album. I then added an IsExcluded property to the Photo entity. Unfortunately, I can't set the Association between the 2 to recognise this filter.

Solution 1: Create a new View called 'IncludedPhotos' and use that in the domain model.
Solution 2: Move to LINQ to Entities.

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