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POMVP: 3rd party controls, How much logic can be put in View layer
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  1. POMVP: 3rd party controls, How much logic can be put in View layer
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    copied!<p>I'm learning MVP pattern, but still have some doubts.</p> <p><a href="http://www.martinhunter.co.nz/articles/MVPC.pdf" rel="nofollow">Martin Hunter</a> in his MVC/MVP overview wrote:</p> <blockquote> <p>In MVP, the view becomes an ultra-thin component whose purpose is purely to provide a presentation to the user. The view catches and handles events raised by the user, but forwards these directly to the presenter who knows how to deal with them.</p> <p>(...)</p> <p>However, with MVP the view catches events raised and forwards them to the controller (presenter)</p> </blockquote> <p>This is fine with buttons and text boxes, but what in case there are some more complex controls? Lets say I'm using 3rd party components, like Devexpress's TreeList control. Assume I want to dinamically build sub-nodes when user clicks expand button "+". Not using any pattern I could code this like that:</p> <pre><code>private void BeforeExpand_EventHandler(object sender, BeforeExpandEventArgs e) { TreeList treeList = sender as TreeList; MyModelObject nodeObj = e.Node.Tag as MyModelObject; treeList.BeginUnboundLoad(); //Create sub-nodes depending on nodeObj treeList.EndUnboundLoad(); } </code></pre> <p>As you can see there are some View-objects, like BeforeExpandEventArgs, TreeListNode, some specific actions like BeginUnboundLoad(), and so on. In that case my View layer cannot be "ultra thin". I cannot pass directly to Presenter objects like BeforeExpandEventArgs because it would affect the Presenter with some View stuff. </p> <p>My question is then: <strong>How much logic I can put into View layer</strong>? For example, is code presented below ok? </p> <pre><code>private void BeforeExpand_EventHandler(object sender, BeforeExpandEventArgs e) { TreeList treeList = sender as TreeList; MyModelObject nodeObj = e.Node.Tag as MyModelObject; treeList.BeginUnboundLoad(); e.Node.Nodes = this.presenter.GetNodes(nodeObj); treeList.EndUnboundLoad(); } </code></pre>
 

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