Monday 29 October 2012

Ubuntu 12.10 - Unable to suspend

I'm having an issue where after I upgraded to the latest version 12.10, the suspend function stopped working. Upon looking at the /var/log/syslog, this is what I found: libupower-glib-CRITICAL: up_client_get_can_suspend: assertion `UP_IS_CLIENT (client)' failed And it looks like there's a bug filed for it: https://bugs.launchpad.net/ubuntu/+source/gnome-session/+bug/1066057 I guess the guys are still trying to solve it...
Posted by at 0 comments

Wednesday 24 October 2012

Knockoutjs - using the same variable with the 'with' binding and nested 'text' binding

I'm working on a demo for a meetup presentation next week, and initially I had something like this: 
 <!DOCTYPE html>  
 <html>  
 <head>  
 <script type="text/javascript" src="js/knockout-2.1.0.js"></script>  
 </head>  
      <body>  
      <p>Choose your costume:   
           <select data-bind="options: availableCostumes, optionsCaption: 'Choose one...', value: selectedCostume"></select>  
      </p>  
      <div data-bind="with: selectedCostume">  
           On Halloween this year, I will be a <span data-bind="text: makeScaryCostume"></span>.  
      </div>  
      </body>  
      <script type="text/javascript">  
        function CostumeViewModel() {  
           var self = this;  
           self.selectedCostume = ko.observable(null);  
           self.availableCostumes = ko.observableArray(['Pirate', 'Ghost', 'Banana']);  
             self.makeScaryCostume = ko.computed(function() {  
                    return "very scary " + self.selectedCostume();  
             }, self);  
        };  
      ko.applyBindings(new CostumeViewModel());  
      </script>  
 </html>
However, whenever I run this, the following error message happens: 
 Uncaught Error: Unable to parse bindings.  
 Message: ReferenceError: makeScaryCostume is not defined;  
 Bindings value: text: makeScaryCostume knockout-2.1.0.js:48  
 a.a.extend.parseBindingsString knockout-2.1.0.js:48  
 a.a.extend.getBindings knockout-2.1.0.js:48  
 a.h.disposeWhenNodeIsRemoved
The problem is that the 'with' binding creates a context for the nested elements, so within that inner div, it doesn't have access to the view model. The solution is to use the built-in $root reference, which refers to the view model. From there you can use the computed method. 
      <div data-bind="with: selectedCostume">  
           On Halloween this year, I will be a <span data-bind="text: $root.makeScaryCostume"></span>.  
      </div
Posted by at 0 comments

Sunday 14 October 2012

Grails UrlMappings.groovy - Mapping a top level controller excludes dbconsole fix

One of the requirements in my app that I'm working on the side involves adding a rewriting rule that maps any top level context to the ProfileController. Initially, it looks like this: 
 class UrlMappings {  
      static mappings = {  
           "/${screenName}" (controller: 'profile', action: 'profile')  
      }  
 }
So far so good. Unfortunately this poses a problem when I wanted to goto the dbconsole, which is a tool exposed by Grails in development mode to check the contents of the H2 in-mem database. Since everything maps to that controller, even the dbconsole went there. There is a solution, and that involves the use of the `constraints` param. We simply just have to add a notEqual validator of 'dbconsole' so that it skips the controller mapping. Since the /dbconsole is defined as a servlet-mapping in web.xml, it will filter to that context after Grails decides it cannot handle that uri.
So here is the solution: 
 class UrlMappings {  
      static mappings = {  
           "/${screenName}" {  
                controller = 'profile'  
                action = 'profile'  
                constraints { screenName(notEqual: 'dbconsole') }}  
      }  
 }
Posted by at 1 comments

Friday 12 October 2012

HTML element: be careful of using element.value where there are newlines!

I'm working on a project where it uses a dirty check mechanism to warn the users on the page to save their data, and it uses element.value to retrieve the value for all form fields, and compare against the values at the time that the user navigates away from the page. This works great but unfortunately I found that element.value and $(element).val() does not always equal each other. You see, in OS specific systems, if there is a new line character, it will interpret it as \r\n, where as other OSes will interpret it as \n. By wrapping the element in jQuery, it will `normalize` the data for you so you don't have to worry about the subtle differences. For us it was essential that they have to be consistent, which is why one should use the jQuery implementation of .val() instead of element.value.
Posted by at 0 comments

Monday 8 October 2012

Grails exception after changing UrlMappings.groovy

I got this strange exception after changing the UrlMappings.groovy in one of my Grails applications today:


 plugins.AbstractGrailsPluginManager Plugin [controllers:2.1.0] could not reload changes to file [/home/tchan/repo/privategram/grails-app/controllers/com/privategram/DashboardController.groovy]: Unable to locate constructor with Class parameter for class org.codehaus.groovy.grails.commons.DefaultGrailsControllerClass  
 java.lang.RuntimeException: Unable to locate constructor with Class parameter for class org.codehaus.groovy.grails.commons.DefaultGrailsControllerClass  
      at java.lang.Thread.run(Thread.java:662)  
 Caused by: java.lang.reflect.InvocationTargetException  
      ... 1 more  
 Caused by: java.lang.NullPointerException  
      ... 1 more  
 [/privategram].[default] Servlet.service() for servlet [default] in context with path [/privategram] threw exception  
 java.lang.RuntimeException: java.lang.RuntimeException: Unable to locate constructor with Class parameter for class org.codehaus.groovy.grails.commons.DefaultGrailsControllerClass  
      at org.codehaus.groovy.grails.web.mapping.filter.UrlMappingsFilter.checkDevelopmentReloadingState(UrlMappingsFilter.java:298)  
      at org.codehaus.groovy.grails.web.mapping.filter.UrlMappingsFilter.doFilterInternal(UrlMappingsFilter.java:199)  
      at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)  
      at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)  
      at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)  
      at org.codehaus.groovy.grails.web.sitemesh.GrailsPageFilter.obtainContent(GrailsPageFilter.java:200)  
      at org.codehaus.groovy.grails.web.sitemesh.GrailsPageFilter.doFilter(GrailsPageFilter.java:151)  
      at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)  
      at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)  
      at javax.servlet.FilterChain$doFilter.call(Unknown Source)  
      at org.grails.plugin.resource.DevModeSanityFilter.doFilter(DevModeSanityFilter.groovy:44)  
      at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)  
      at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)  
      at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:369)  
      at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:109)  
      at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:83)  
      at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:381)  
      at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:97)  
      at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:381)  
      at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:78)  
      at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:381)  
      at org.springframework.security.web.authentication.rememberme.RememberMeAuthenticationFilter.doFilter(RememberMeAuthenticationFilter.java:112)  
      at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:381)  
      at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:54)  
      at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:381)  
      at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:187)  
      at org.codehaus.groovy.grails.plugins.springsecurity.RequestHolderAuthenticationFilter.doFilter(RequestHolderAuthenticationFilter.java:40)  
      at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:381)  
      at org.codehaus.groovy.grails.plugins.springsecurity.MutableLogoutFilter.doFilter(MutableLogoutFilter.java:79)  
      at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:381)  
      at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:79)  
      at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:381)  
      at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:168)  
      at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:346)  
      at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:259)  
      at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)  
      at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)  
      at org.codehaus.groovy.grails.web.servlet.mvc.GrailsWebRequestFilter.doFilterInternal(GrailsWebRequestFilter.java:69)  
      at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)  
      at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)  
      at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)  
      at org.codehaus.groovy.grails.web.filters.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:69)  
      at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)  
      at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)  
      at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)  
      at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)  
      at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)  
      at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:346)  
      at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:259)  
      at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)  
      at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)  
      at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:225)  
      at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:169)  
      at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)  
      at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)  
      at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)  
      at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)  
      at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:999)  
      at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:565)  
      at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:309)  
      at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)  
      at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)  
      at java.lang.Thread.run(Thread.java:662)  
 Caused by: java.lang.RuntimeException: Unable to locate constructor with Class parameter for class org.codehaus.groovy.grails.commons.DefaultGrailsControllerClass  
      ... 1 more  
 Caused by: java.lang.reflect.InvocationTargetException  
      ... 1 more  
 Caused by: java.lang.NullPointerException  
      ... 1 more
I doubled checked my UrlMappings again and they seemed fine, so I was pretty certain it was something to do with the reloading, and sure enough, after restarting the app, everything was okay. I guess they didn't tell you that not everything is reloadable?

Posted by at 0 comments
Subscribe to: Posts (Atom)