如何将HashMap传递给gsp页面然后再传回控制器？

Question

I have values that I need to pass around in the structure of

type1 : value1, value2, value3
type2 : value4, value5, value6
type3 : value7, value8, value8

So I made a HashMap<String, ArrayList<String>>() in my controller and I pass it to my gsp file like this:

def queryMap = new HashMap<String, ArrayList<String>>()
//fill in data
render(template: "/item/myPage", model: [queryMap: queryMap])

Then in my gsp page I would like to pass it back to my controller like this:

<g:link action="myNewPage" controller="item" params='[queryMap: "${queryMap}"]'>fun</g:link>

Then in myNewPage controller method I would like to get the map like this:

def queryMap = params.queryMap as HashMap

But for some reason my map is not getting passed around correctly? How can I properly pass a map with a list to my gsp file then back to my controller?

If you need nay more information let me know.

Answer 1

Use as below without interpolating queryMap (without ${} )

<g:link action="myNewPage" 
        controller="item" 
        params="[queryMap: queryMap]">fun</g:link>

Moreover, you do not need to infer the type as HashMap , by default it is. I would also agree to @Isammoc about coming up with an appropriate data model (by using form etc.) instead of flowing over the model back and forth.

Answer 2

You may try to serialize the whole map and then pass it around and deserialize when you need it. You could convert the whole Map into JSON and pass it as a String.