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POOnly retrieve specific columns when using Critera queries?
 

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  1. POOnly retrieve specific columns when using Critera queries?
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    <p>I'm propositioning NHibernate for a project we're doing at my company and I'd like to know if NHibernate can be optimized to only retrieve specific columns on a table when using the Criteria query language.</p> <p>For example. Let's say I have a table with 30 columns on it and this is mapped to an object using NHibernate that is a 1-for-1 match against the table. However, for a particular function of the system I only care about two of those columns.</p> <p>Now, I know I can use HQL and do a <code>CreateQuery</code> that will accomplish this but that requires I create a constructor for each combination of fields I'd like to selectively retrieve. This could be a huge pain from a maintenance standpoint since I won't catch missing constructors till runtime.</p> <p>I like the Criteria query language since it produces parametrized SQL instead of straight SQL queries from HQL. I see there is an "Exclude" model for not including certain columns but in most cases I will include more columns than exclude.</p> <p>Thanks to the comment below I looked into projections and this still isn't quite the ideal situation for me. When using the following:</p> <pre><code>var list = session .CreateCriteria(typeof (Task)) .SetProjection(Projections .ProjectionList() .Add(Projections.Property("Id"))) .List(); </code></pre> <p>I end up with the variable <code>list</code> just being ints, I'd prefer to have my full Task object but with all the fields set to their default values. Is this even possible? Everything I see so far says no.</p>
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    1. USBartoszKP
    1. USMatthew Bonig
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      1. USMagnus Bertilsson
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    1. COPlease see the update to my post in answer to you question.
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      1. USDanielg
 

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