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POpersisting a property that relies on other properties and custom transforms
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  1. POpersisting a property that relies on other properties and custom transforms
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    copied!<p>I'm wondering how to persist a property that depends on both regular persisted properties (e.g. string, int) as well as some custom transforms of their own.</p> <p>For instance suppose I have</p> <pre><code>class A { public int Id {get; set;} public string SomeString {get; set;} public object SpecialProperty {get; set;} } </code></pre> <p>suppose that persisting SpecialProperty requires reading SomeString and depending on it's value, producing some byte[] which can then be stored in the database.</p> <p>My first thought was to use an IUserType, but this the method NullSafeGet(IDataReader rs, string[] names, object owner) is invoked before (or actually, during) SomeString is persisted (or not), so it is not set.</p> <p>My second thought was to use a ICompositeUserType and some rather convoluted setup using wrappers.</p> <p>My third thought was maybe I could implement ILifecycle and hook the OnLoad() method. But if I wanted to do that I would need to create a seperate property for the byte[] payload which I don't really want to store. This certainly seems the easiest to implement but also somewhat inelegant.</p> <p>e.g.</p> <pre><code>class A : ILifecycle { public int Id {get; set;} public string SomeString {get; set;} public object SpecialProperty {get; set;} private byte[] payloadData { get; set; } public void OnLoad(ISession s, object id) { SpecialProperty = customIn(SomeString, payloadData); payloadData = null; } static object customIn(string a, byte[] payload) { // ... } } </code></pre> <p>Does anybody know of an an easier and possibly more concise way?</p>
 

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