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POCannot access the parameter of a Menu.param from a Lift Snippet
 

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  1. POCannot access the parameter of a Menu.param from a Lift Snippet
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    <p>I'm trying to extract the parameter from a Lift Menu.param within a snippet so that I can use it to create a named Comet. However, I get a NullPointerException when I try to pass the parameter to the snippet using SnippetDisptach in my Boot.scala, as suggested here: <a href="http://comments.gmane.org/gmane.comp.web.lift/44299" rel="nofollow">http://comments.gmane.org/gmane.comp.web.lift/44299</a> </p> <p>I've created the Menu item as follows:</p> <pre><code>object AnItemPage { // create a parameterized page def menu = Menu.param[Item]("Item", "Item", s =&gt; fetchItem(s), item =&gt; item._id.toString) / "item" private def fetchItem(s:String) : Box[Item] = synchronized { ItemDAO.findById(ObjectId.massageToObjectId(s)) } } </code></pre> <p>I've added the menu to SiteMap. I've also created a Snippet which I would like to pick up the Item parameter. (I'm using fmpwizard's InsertNamedComet library here):</p> <pre><code> class AddCometItemPage(boxedItem: Box[Item]) extends InsertNamedComet with DispatchSnippet{ val item : Item = boxedItem.openOr(null) override lazy val name= "comet_item_" + item._id.toString override lazy val cometClass= "UserItemCometActor" def dispatch = null } </code></pre> <p>My next step is to crate an instance of this class as demonstrated by David Pollak here: <a href="http://comments.gmane.org/gmane.comp.web.lift/44299" rel="nofollow">http://comments.gmane.org/gmane.comp.web.lift/44299</a></p> <p>This is what I have added to my Boot.scala:</p> <pre><code>LiftRules.snippetDispatch.append { case "item_page" =&gt; new AddCometItemPage(AnItemPage.menu.currentValue) } </code></pre> <p>My item.html references this snippet:</p> <pre><code> &lt;div class="lift:item_page"&gt; </code></pre> <p>I get the following null pointer exception when I compile and run this:</p> <pre><code>Exception occurred while processing /item/5114eb4044ae953cf863b786 Message: java.lang.NullPointerException net.liftweb.sitemap.Loc$class.siteMap(Loc.scala:147) net.liftweb.sitemap.Menu$ParamMenuable$$anon$9.siteMap(Menu.scala:170) net.liftweb.sitemap.Loc$class.allParams(Loc.scala:123) net.liftweb.sitemap.Menu$ParamMenuable$$anon$9.allParams(Menu.scala:170) net.liftweb.sitemap.Loc$class.net$liftweb$sitemap$Loc$$staticValue(Loc.scala:87) net.liftweb.sitemap.Menu$ParamMenuable$$anon$9.net$liftweb$sitemap$Loc$$staticValue(Menu.scala:170) net.liftweb.sitemap.Loc$$anonfun$paramValue$2.apply(Loc.scala:85) net.liftweb.sitemap.Loc$$anonfun$paramValue$2.apply(Loc.scala:85) net.liftweb.common.EmptyBox.or(Box.scala:646) net.liftweb.sitemap.Loc$class.paramValue(Loc.scala:85) net.liftweb.sitemap.Menu$ParamMenuable$$anon$9.paramValue(Menu.scala:170) net.liftweb.sitemap.Loc$$anonfun$currentValue$3.apply(Loc.scala:114) net.liftweb.sitemap.Loc$$anonfun$currentValue$3.apply(Loc.scala:114) net.liftweb.common.EmptyBox.or(Box.scala:646) net.liftweb.sitemap.Loc$class.currentValue(Loc.scala:114) net.liftweb.sitemap.Menu$ParamMenuable$$anon$9.currentValue(Menu.scala:170) bootstrap.liftweb.Boot$$anonfun$lift$8.apply(Boot.scala:107) bootstrap.liftweb.Boot$$anonfun$lift$8.apply(Boot.scala:106) net.liftweb.util.NamedPF$$anonfun$applyBox$1.apply(NamedPartialFunction.scala:97) net.liftweb.util.NamedPF$$anonfun$applyBox$1.apply(NamedPartialFunction.scala:97) net.liftweb.common.Full.map(Box.scala:553) net.liftweb.util.NamedPF$.applyBox(NamedPartialFunction.scala:97) net.liftweb.http.LiftRules.snippet(LiftRules.scala:711) net.liftweb.http.LiftSession$$anonfun$net$liftweb$http$LiftSession$$findSnippetInstance$1.apply(LiftSession.scala:1506) net.liftweb.http.LiftSession$$anonfun$net$liftweb$http$LiftSession$$findSnippetInstance$1.apply(LiftSession.scala:1506) net.liftweb.common.EmptyBox.or(Box.scala:646) net.liftweb.http.LiftSession.net$liftweb$http$LiftSession$$findSnippetInstance(LiftSession.scala:1505) net.liftweb.http.LiftSession$$anonfun$locateAndCacheSnippet$1$1$$anonfun$apply$88.apply(LiftSession.scala:1670) net.liftweb.http.LiftSession$$anonfun$locateAndCacheSnippet$1$1$$anonfun$apply$88.apply(LiftSession.scala:1669) </code></pre> <p>Has anybody any idea where I'm going wrong? I've not been able to find a lot of information on Menu.param.</p> <p>Thank you very much for your help.</p> <p>f</p>
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    1. COHey fin :) Which version of Lift/Scala are you running? 2.4 or 2.9 or 2.5-SNAPSHOT on 2.10 or something like that? :)
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    2. COHi Franz. I'm using Scala 2.9.1 with lift 2.5-M2. Thanks very much for looking at this!
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    3. COHm, this behavior is really weird. Have you tried the lift google groups? My guess is that it's a bug, but please ask in the groups first before opening an issue. Sadly my lift netty port isnt far enough to test it with that. :)
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      1. USFranz Bettag
 

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