Polymer linking via json - json

Question

Sorry this is such a basic newbie question; I can't find anything in the Polymer documents. Say I have a set of cards - like in the getting started tutorial - each with some info. Can I add a button supplying an anchor/link to more detail/ document/image/pdf... Is it possible to set those links into polymer via json?
Here is what I've tried:
Placing url links (tried absolute and relative) in json, like:(excerpt){
"uid": 4,
"text" : "Blah blah blah",
"Legal" : "Case",
"iconurl" : "../images/svgs/goto.svg",
"url":"http://www.bailii.org/ew/cases/EWHC/Admin/2013/314.html",
"username" : "BBCS",
"avatar" : "../images/svgs/complaint.svg",
"favorite": false,
"stage": "incident"
},
{
"uid": 5,
"text" : "Blah blah blah",
"Legal" : "Contact Guidance",
"iconurl" : "../images/svgs/goto.svg",
"url":"../assets/docs/stuff.pdf",
"username" : "SCSC",
"avatar" : "../images/svgs/complaint.svg",
"favorite": false,
"stage": "incident"
}
...and then, in post-list, imported paper-button and paper-icon-button, and used paper-icon-button to link to "iconurl", like so:
<paper-icon-button src="{{post.iconurl}}" onclick="_onclick()">Go</paper-icon-button>
This binding on src doesn't work. Nor does explicitly setting a custom icon on src:
e.g. src="../images/svgs/goto.svg" - but in both cases the text Go does appear as a paper button. If I place the icon source inside paper-icon-button css style as background-image then it does show up - repeatedly... as long as there is text also. No text; no image.
Then in script tag in post-list template I have placed an _onclick() function:
function _onclick(){
document.getElementById("{{post.url}}");
};
with and without handlebars...
Here is the full code for post-list.html. ( I have taken the postcard tutorial and am playing about with it...).
The paper-icon-button now works in this scenario. The greyed out version didn't. And as for my javascript attempts to bind to json - all commented out here below - well, nothing works.
<link rel="import" href="../components/polymer/polymer.html">
<link rel="import" href="../post-service/post-service.html">
<link rel="import" href="post-card.html">
<link rel="import"
href="../components/paper-button/paper-button.html">
<link rel="import"
href="../components/paper-icon-button/paper-icon-button.html">
<polymer-element name="post-list" attributes="show">
<template>
<style>
:host {
display: block;
width: 100%;
}
post-card {
margin-bottom: 30px;
}
paper-icon-button{
float:right;
margin-left: 30px;
margin-right: 20px;
color: #0dddad;
<!--background-image: url("../images/svgs/goto.svg");-->
}
</style>
<post-service id="service" posts="{{posts}}">
</post-service>
<div layout vertical center>
<template repeat="{{post in posts}}">
<post-card>
<img src="{{post.avatar}}" width="70" height="70">
<paper-icon-button
raisedButton
class="colored"
iconSrc="../images/svgs/eyeyeY.svg"
on-click="{{goLink}}"></paper-icon-button>
<!--<paper-icon-button src="../images/svgs/eyeyeO.svg" onclick="_onclick()">o</paper-icon-button>-->
<h2>{{post.username}}</h2>
<p>{{post.text}}</p>
<h4>{{post.Legal}}</h4>
</post-card>
</template>
</div>
</template>
<script>
Polymer({});
//Polymer('post-list', {
//goLink: function(e) {
//window.getElementById=e.target.open({{api/post.url}});
//return document.getElementById("post.url")
//document.location.href =e.target("{{post.url}}");
// };
//});
</script>
</polymer-element>