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PODynamically determining dependency based on user parameters
 

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    <h3>Problem</h3> <p>I currently have a factory that depends on a few parameters to properly decide which object to return. This factory is not yet bound to DI. As I understand it NInject uses providers as a factory.</p> <p>Here is what I currently have. I'll warn you it's not pretty.</p> <pre><code>public interface IRole { string Name { get; } } public class FooRole : IRole { public string Name { get { return "Foo Role"; } } } public class BarRole : IRole { public string Name { get { return "Bar Role"; } } } public class FooBarRoleModule : NinjectModule { public override void Load() { Bind&lt;IRole&gt;().ToProvider&lt;RoleProvider&gt;(); } } public class RoleProvider : Provider&lt;IRole&gt; { protected override IRole CreateInstance(IContext context) { var isNewParameter = context.Parameters .Where(x =&gt; x.Name == "isNew") .Select(x =&gt; x.GetValue(context)) .Cast&lt;bool&gt;() .FirstOrDefault(); if (isNewParameter) return new FooRole(); return new BarRole(); } } var role = kernel.Get&lt;IRole&gt;(new ConstructorArgument("isNew", true)); Console.WriteLine(role.Name); </code></pre> <p>I'm almost certain this is not the proper way of dynamically injecting dependencies, however it does work. And frankly, looking at what I've hacked together doesn't seem to make much sense.</p> <p>The reason I need to dynamically resolve the dependency is that during the life cycle of the application the end-user can assume several roles. The sample posted above is pretty simply but the parameters (currently only isNew) would determine would object to inject.</p> <h3>Question</h3> <p>What is the proper way to use a provider with parameters not known at run time? These parameters would be passed in whenever the user triggers the code that could give them a different role.</p> <p>Thank you.</p> <h3>Edit</h3> <pre><code>public class RoleFactory : IRoleFactory { public IRole Create(bool isNew) { if (isNew) return new BarRole(); return new FooRole(); } } </code></pre> <p>Bind it with <code>Bind&lt;IRoleFactory&gt;().To&lt;RoleFactory&gt;();</code> and use it like so.</p> <pre><code>var role = kernel.Get&lt;IRoleFactory&gt;(); Console.WriteLine(role.Create(true).Name); </code></pre> <p>This revised version does look better and makes more sense, however I believe I missed some key details in your post. Wanted to add that the <code>isNew</code> parameter would be true if the factory was called from for example a "Create New Event" button.</p>
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    1. COAbstract Factory is your friend: http://stackoverflow.com/questions/1943576/is-there-a-pattern-for-initializing-objects-created-via-a-di-container/1945023#1945023
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    2. COThanks, Mark. I will look at that link.
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    3. COI'm a little confused about the example you posted. You use `Create()` to accept parameter(s) to help create the proper object. Isn't that the same as having `Initialize()` in your factory? I've edited my question to include my revised code according to your answer.
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