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POAccessing attributes on fields using extension method
 

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    <p>I want to check custom attributes on my class members (fields only) by using an extension method.</p> <pre><code>public class DatabaseIdAttribute : Attribute { public int ID { get; set; } public DatabaseIdAttribute(int id) { this.ID = id; } } public class MyClass { [DatabaseId(1)] double Height {get;set;} [DatabaseId(2)] double Width {get;set;} double Area { get { return this.Height * this.Width; } } </code></pre> <p>I want to use LINQ expression in the extension method to access the class field instead of passing magic strings.</p> <pre><code>var myClass = new MyClass(); var attribute = myClass.GetAttribute&lt;DatabaseIdAttribute&gt;(c =&gt; c.Height); </code></pre> <p>Is it possible to achieve?</p> <p>[EDIT]</p> <p>For the time being, I have achieved the following with the help of @leppie </p> <pre><code> public static MemberInfo GetMember&lt;T, R&gt;(this T instance, Expression&lt;Func&lt;T, R&gt;&gt; selector) { var member = selector.Body as MemberExpression; if (member != null) { return member.Member; } return null; } public static T GetAttribute&lt;T&gt;(this MemberInfo member) where T : Attribute { return member.GetCustomAttributes(false).OfType&lt;T&gt;().SingleOrDefault(); } </code></pre> <p>which enables to get the attribute in the following way</p> <pre><code>var c = new MyClass(); var attribute = c.GetMember(m =&gt; m.Height).GetAttribute&lt;DatabaseIdAttribute&gt;(); </code></pre> <p>but I want to be able to access it in the following way</p> <pre><code>var c = new MyClass(); var attribute = c.GetAttribute&lt;DatabaseIdAttribute&gt;(m =&gt; m.Height); </code></pre>
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    1. COYes, it is possible, and trivial. What have you tried?
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    2. COYes, it does seem trivial, but i'm unable to find an example. That is why I asked here.
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    3. CODo not use `object`, else there will be a conversion involved. Use an additional generic parameter (ie `R`). Also, the member could be a `PropertyInfo` too (which it is in this case). `MemberInfo` might suffice here if you are only interested in the attribute.
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