页面刷新后如何在grails中保留下拉选择？

Question

I know that there are already some questions about dropdown selection retaining but please don't close this one.

I have a login page with language dropdown list. User chooses a language and the page is refreshed with the new language. The selection, of course, disappears and the lang parameter isn't moved to the whole application. Home page opens with the default language, not with the one user wants.

Here is my code:

.gsp file

    <g:select style="width: 60px; background-color: transparent; border: 0px;" 
    onchange="goToPage(this.value)" name="lang"              
    from="${LangCodeBook.list()}" value="" noSelection="['':'...']">
    </g:select>


    <script type="text/javascript">

       function goToPage(lang){
   if(lang=='GER'){ 
           window.location.href = "?lang=de_DE";
   }
   else if(lang=='RUS'){ 
           window.location.href = "?lang=ru_RU";
   }
   else if(lang=='ENG'){ 
           window.location.href = "?lang=en_GB";
   }
     }
   </script>

On the other side is MyEventListener.groovy and he saves into an object all the params (username, password, lang).

        def paramObject=RequestContextHolder.currentRequestAttributes().getParams()

The problem is that the lang param stays blank.

Please help. Thanks.

Answer 1

Just give the select control an id , read the lang value from the query string & set it as the selected value of the select control onload as shown below.

document.getElementById('lang').value= getParameterByName("lang");

<g:select style="width: 60px; background-color: transparent; border: 0px;" 
    onchange="goToPage(this.value)" name="lang" id="lang" 
    from="${LangCodeBook.list()}" value="" noSelection="['':'...']">
    </g:select>


    <script type="text/javascript">
       document.getElementById('lang').value= getParameterByName("lang");
       function goToPage(lang){
       if(lang=='GER'){ 
           window.location.href = "?lang=de_DE";
       }
       else if(lang=='RUS'){ 
           window.location.href = "?lang=ru_RU";
       }
       else if(lang=='ENG'){ 
           window.location.href = "?lang=en_GB";
       }
     }
     function getParameterByName(name) {
     name = name.replace(/[\[]/, "\\\[").replace(/[\]]/, "\\\]");
     var regexS = "[\\?&]" + name + "=([^&#]*)";
     var regex = new RegExp(regexS);
     var results = regex.exec(window.location.search);
     if (results == null) return "";
     else return decodeURIComponent(results[1].replace(/\+/g, " "));
     }
   </script>

Answer 2

very simple

Use Ajax and Session varible in grails controller ...

ajax function jquery on change function on the drop down box

<g:javascript>
        function onChange(){
        //id = $this.value;
        $.ajax({ 
        context: $(this),
        url:"${resource()}"+"/yourLanagueController/yourSelectionHolderAction",                             type:"POST",
        data:{"dropdownboxid":id}
        });
        }
        </g:javascript>

your controller and session variables

on login page some where make you session varible to null;

`def session.selectedlanagueid = null`

def yourSelectionHolderAction(params){

 //always hold one ID only so when u
//set session varible make to null first then add
            session.selectedlanagueid = null 
        if(params.id)
                 session.selectedlanagueid = id;

        render 'test' // or '' // or any valid json render result
    }

ALLOHA !!!