如何将javascript变量传递到Groovy块中

Question

I need to manage a groovy list object in my javascript function. I have a groovy block into a javascript function. I tried with this:

var obj = ${mediaObjectInstanceList as grails.converters.JSON}[index];

and this:

var obj = ${mediaObjectInstanceList.get(index)};

but both are wrong. In the second I would specify the "index" int javascript variable out of the groovy block.

Answer 1

You can't do that in a way you defined it.

Though, there are lots of possibilities to accomplish that.

One of them is to define a JS-variable and fill it with groovy model values:

var myArray = new Array( 
<g:each in="${mediaObjectInstanceList}" var="obj" status="ix">
  ${status ? ',' : ''} '${obj}'
</g:each>
);

then you can traverse this array in JS using plain subscript notation:

var someVal = myArray[ index ];

Answer 2

As answered by injecteer, you can't do that. Mostly because :

• groovy blocks are executed server side : they can't be aware of variables in javascript only know by the browsers.
• javascript is executed client side, ie. browsers don't know the variable mediaObjectInstanceList (only known by your grails application).

Two (main) solutions :

• you don't know your index when the page is generated (no params in your request) => You have to generate the whole array server side (groovy) to be available at client side (javascript).

  var mediaObjectInstanceListInJS = new Array( ${mediaObjectInstanceList.collect { it as JSON}.join(',')} ); var someVal = mediaObjectInstanceListInJS[index];

• you already have the index server side (with params in your request) => you can get in groovy block only your selected object :

  var someVal = ${mediaObjectInstanceListInJS[params.index] as JSON} ;