how to store multifield nodes as JSON in aem 6.5 (coral 3) ?

Hey thanks for reply but that way it's will be stored as an array like comma separated 

I have fixed by jqury dialog logic i will capture multifield data and concert into json and store into text field please refer below code 

console.log("client multifields....");
(function(document, $, ns) {
"use strict";
$(document).on("click", ".cq-dialog-submit", function(e) {
var attributelist =$("input[name='./fname']").attr("data-attribute1").split(",");

console.log("attributelist"+attributelist.size);
var parentlabel = "./"+ $("input[name='./fname']").attr("data-parentlabel");

var $formminmax = $(this).closest("form.foundation-form");

var field = $formminmax.find("[data-granite-coral-multifield-name='"+parentlabel+"']");
var totalLinkCount = field.children('coral-multifield-item').length;
var test = field.children('coral-Form-fieldwrapper').name;

var jsonObj = [];

for (var i = 0; i < totalLinkCount; i++) {
var item = {}
console.log("pp"+'itemXX'.replace('XX',i));

for (var j=0; j < attributelist.length; j++) {
var itemname = './bookdetailswithmap/item'+i+'/./'+attributelist[j];
item [attributelist[j]] =field.find($("[name='"+itemname+"']")[0]).val();
}
jsonObj.push(item);
}
var obj2 = {"parentlabel": jsonObj };
snippet.log(obj2.personalization.name);
$('.fnameclass').val(JSON.stringify(jsonObj));
});
})(document, Granite.$, Granite.author);