Demo input

gistfile1.html.erb

<button type="button" name="submit" class="btn-save btn-primary btn">Save</button>

<script>
  $(document).ready(function() {
    $('.btn-save').on('click', function() {
      $.ajax({
        type: 'POST',
        url: '/workspaces/<%= params[:id] %>',
        data: {
          _method: "patch",
          nodeDataArray: [
            {"key":"G1", "isGroup":true, "pos":"0 0", "size":"200 200", "name":"A Group 1"},
            {"key":"G2", "isGroup":true, "pos":"200 0", "size":"200 200", "name":"A Group 2"},
            {"key":"Sec-1", "isGroup":true, "pos":"0 200", "size":"200 200", "name":"A Group 3"},
            {"key":"Sec-2", "isGroup":true, "pos":"200 200", "size":"200 200", "name":"A Group 4"},
            {"key":"b", "color":"#81D4FA", "size":"50 50", "pos":"50 50", "group":"G1", "name":"user 1", "type":"1", "user_id":"3"},
            {"key":"g", "color":"#B2FF59", "size":"100 50", "pos":"250 50", "group":"G2", "name":"user 2", "type":"1", "user_id":"4"},
            {"key":"g2", "color":"#B2FF59", "pos":"250 100", "group":"G12", "size":"50 50", "name":"user 3", "type":"1", "user_id":"5"},
            {"key":"g3", "color":"#B2FF59", "pos":"300 100", "group":"G2", "size":"50 50", "name":"user 4", "type":"1", "user_id":"6"},
          ]
        },
        dataType: 'json',
        success: function(data) {
          console.log(data);
        },
        error: function(data) {
          console.log(data);
        }
      });
    });
  });
</script>