Loops in GSP

Loops are one of the most important and useful part of every programming language. Grails provides various loops in controller and view. Following are the loops in GSP:

• each: each tag is used to iterate over each element of a list.

  <g:each in="${books}" status="i">
      <p>Index: ${i}</p>
      <p>Title: ${it.title}</p>
      <p>Author: ${it.author}</p>
  </g:each>
  

  where

  • in – The object to iterate over
  • status (optional) – The name of a variable to store the iteration index in.
  • var (optional) – The name of the item. Defaults “it”.
• while: while is used to executes a condition until the condition returns false.

  <g:while test="${i < 5}">
      <%i++%>
      <p>Current i = ${i}</p>
  </g:while>
  

  where

  • test – The conditional expression
• unless: unless is used to renders its body unless all of the specified conditions (test and/or environment) are true.

  <g:unless test="${name == 'fred'}">
      Hello ${name}!
  </g:unless>
  
  <g:unless env="production">
      debug: $someDebug
  </g:unless>
  

  where

  • test – The expression to test
  • env – An environment name

  Note:- If both are supplied, they are combined using AND.

Hope this helps 🙂 .