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POChange EF entity with descendant proxy class
 

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    <p>I have .Net 4.0 application which use EntityFramework 5.0 to access data from MS SQL database.</p> <p>I use database first approach. All tableas are mapped to POCO entities, which has additional properties which contains entities which is recieved from web service.</p> <p>Database:</p> <pre><code>WH_Product (Id, NomenklatureId, SeriesId, Quantity) </code></pre> <p>Service have such data:</p> <pre><code>Nomenklature (Id, Name, Producer...) Series (Id, Number, Date...) </code></pre> <p>POCO entity:</p> <pre><code>Product (Id, NomenklatureId, Nomenklature, SeriesId, Series, Quantity) </code></pre> <p>I have a problem with Repository realisation. I need to implement lazy loading for Nomenklature and Series properties. </p> <p>I make ProductProxy class which implements such loading like this:</p> <pre><code>public class ProductProxy:Product { private Nomenklature _nomenklature; public override Nomenklature Nomenklature { get { if (_nomenklature==null) { _nomenklature = &lt;code for load Nomenklature from webService by base.NomenklatureId&gt; } return _nomenklature; } } private Series _series; public override Series Series { get { if (_series==null) { _series = &lt;code for load Series from webService by base.NomenklatureId&gt; } return _series; } } } </code></pre> <p>Then change Person class to PersonProxy class in DbContext.</p> <pre><code>public class ProductContext:DbContext { ... public DbSet&lt;PersonProxy&gt; Person {get; set;} ... } </code></pre> <p>The load method:</p> <pre><code>public List&lt;Person&gt; GetPersons() { using (var ctx = new ProductContext()) { var persons = ctx.Person.AsEnumerable().Cast&lt;Person&gt;().ToList(); return persons; } } </code></pre> <p>Question: Is this a better way to realize GetPersons method without AsEnumerable().Cast()? Is this another way of changing the entity type with the descendant proxy type?</p>
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    1. COWith WCF data services you can use Expand: http://stackoverflow.com/questions/12438481/wcf-data-services-expand-as-linq-statement
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      1. USGert Arnold
    2. COI'm not the web service owner and service have no OData interface.
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    3. COAre you accessing these fields on every queried entity object? If so, I would move the loading logic to ctx.ObjectMaterialized event handler, which would leave original POCO intact without the need for descendant.
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      1. USJacek Gorgoń
 

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