PagerTagLib.groovy

PagerTagLib.java

package com.example

import org.springframework.web.servlet.support.RequestContextUtils as RCU

class PagerTagLib {

  /**
     * Creates next/previous links to support pagination for the current controller
     * This is developed to avoid problems with the PostgreSQL count(*) bug.
     * http://sql-info.de/postgresql/postgres-gotchas.html#1_7
     * 
     * <g:pager total="${accountListInstance.size()}" params="${params}" />
     */
    def pager = { attrs ->
        def writer = out
        if (attrs.total == null) {
            throwTagError("Tag [pager] is missing required attribute [total] which is the total showing for the current page")
        }

        def messageSource = grailsAttributes.messageSource
        def locale = RCU.getLocale(request)

	  	def total = attrs.int('total') ?: 0
	  
        def action = (attrs.action ? attrs.action : (params.action ? params.action : "list"))
        def offset = params.int('offset') ?: 0
        def max = params.int('max')

        if (!offset) offset = (attrs.int('offset') ?: 0)
        if (!max) max = (attrs.int('max') ?: 10)

        def linkParams = [:]
        if (attrs.params) linkParams.putAll(attrs.params)
        linkParams.offset = offset - max
        linkParams.max = max
        if (params.sort) linkParams.sort = params.sort
        if (params.order) linkParams.order = params.order

        def linkTagAttrs = [action:action]
        if (attrs.controller) {
            linkTagAttrs.controller = attrs.controller
        }
        if (attrs.id!=null) {
            linkTagAttrs.id = attrs.id
        }
        linkTagAttrs.params = linkParams

        // determine paging variables
	  	def isFirstStep = (offset == 0)
	  	def isLastStep = (total < max)

        // display previous link when not on firststep
        if (!isFirstStep) {
            linkTagAttrs.class = 'prevLink'
            linkParams.offset = offset - max
            writer << link(linkTagAttrs.clone()) {
                (attrs.prev ? attrs.prev : messageSource.getMessage('paginate.prev', null, messageSource.getMessage('default.paginate.prev', null, 'Previous', locale), locale))
            }
        }

        // display next link when not on laststep
        if (!isLastStep) {
            linkTagAttrs.class = 'nextLink'
            linkParams.offset = offset + max
            writer << link(linkTagAttrs.clone()) {
                (attrs.next ? attrs.next : messageSource.getMessage('paginate.next', null, messageSource.getMessage('default.paginate.next', null, 'Next', locale), locale))
            }
        }
    }

}