wedatajsoninput.user.js

// ==UserScript==
// @name           WedataJSONInput
// @namespace      http://d.hatena.ne.jp/murky-satyr
// @description    Fills the form by prompting json text.
// @include        http://wedata.net/databases/*/items/new
// @include        http://wedata.net/items/*/edit
// ==/UserScript==
with(document) with(getElementById('item').appendChild(createElement('a'))){
  href = 'javascript:';
  innerHTML = '<b>[JSON]</b>';
  addEventListener('click', function(){
    for(var [k, v] in Iterator(eval('('+ (prompt('JSON', '{}')
                                          .replace(/[^\}]*$/, ')')))))
      (getElementById('data['+k+']')||getElementById('name')||0).value = v;
  }, false);
}