Groovy and Grails books

The catalog of Groovy and Grails books keeps growing, so if you are in the market for some, check out these sources:

Pragmatic programmer


Apress


Manning


On Amazon:

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mappings closure does not exists for class UrlMappings

I've just started working on a new grails application, and early in the piece I hit this error: 2008-03-05 18:39:20.715::WARN: Failed startup of context org.mortbay.jetty.webapp.WebAppContext@1fcb845{/jtchat,/home/prule/workspace/jtchat/web-app} org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.codehaus.groovy.grails.plugins.web.taglib.ApplicationTagLib': Initialization of bean failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'grailsUrlMappingsHolder': Cannot resolve reference to bean 'urlMappingsTargetSource' while setting bean property 'targetSource'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'urlMappingsTargetSource': Cannot resolve reference to bean 'grailsUrlMappingsHolderBean' while setting constructor argument; nested exception is org.springframework.beans....
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Over typing -Dskip.junit=true

I generally prefer Maven2, but I'm currently on a project using a custom ant build script - and I'm over having to type -Dskip.junit=true when I just want to generate a quick jar without running the tests. To easily switch off tests, I modified ant.bat so that it looks for a command line parameter 'st' and if found, it will substitute it with -Dskip.junit=true. In Ant 1.7.0, you just need to change line 68 in block ':setupArgs' from set ANT_CMD_LINE_ARGS=%ANT_CMD_LINE_ARGS% %1 to if ""%1""==""st"" (set ANT_CMD_LINE_ARGS=%ANT_CMD_LINE_ARGS% -Dskip.junit=true) else (set ANT_CMD_LINE_ARGS=%ANT_CMD_LINE_ARGS% %1) So, the whole block reads (from line 65): :setupArgs if ""%1""=="""" goto doneStart if ""%1""==""-noclasspath"" goto clearclasspath if ""%1""==""st"" (set ANT_CMD_LINE_ARGS=%ANT_CMD_LINE_ARGS% -Dskip...
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When tests become hard

A friend contacted me for advice. He was having trouble writing a test for some code. I asked him to send me the code and the test so I could see what was going on. I encounter this problem quite frequently, so I thought I'd post one of my responses... Okay, here is where I think you are going wrong, and when writing tests becomes hard, it’s usually because of this. It’s important to layer your applications. Web/Services/DB – at least conceptually. What you have is a class that does everything. Web and Service. No-one can reuse your file processing logic without using the web, not even tests! A nice way to code would be to: Write a UNIT test that attempts to process a file. It passes in a file X and asserts that the result is Y. It won’t compile because you haven’t written the file processing code yet! Now you write the service which processes the file The test will compile and run now, but probably fail because you forgot something. Now you can fix your service And ...
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