fabric js无法读取未定义的属性“ src”

Question

当我想使用for循环更改源图像并切换大小写以检测图像对象的ID时，我有一个src属性为undefined的代码。这是我的代码。

function buildTable(results) {
  var data = results.data;
  let gbr;

  for (i = 0; i < data.length; i++) {

    var c = "<canvas id='can" + i + "' class='printCanvas' ></canvas><br>";
    $("body").append(c);
    canvas2[i] = new fabric.Canvas('can' + i + '');
    canvas2[i].setWidth(298);
    canvas2[i].setHeight(420);

    if (data[i] != "") {
      var row = data[i];
      var cells = row.join(",").split(",");
      // console.log(cells);    
    }

    canvas2[i].loadFromJSON(canvas.toJSON(['id', 'qrcode']), function() {}, function(o, object) {
      switch (object.id) {
        case 'id':
          object.text = cells[1];
          break;
        case 'daerah':
          object.text = cells[3];
          break;
        case 'tgl':
          object.text = cells[2];
          break;
        case 'qrcode':
          gbr = object;
          object.setSrc(makeQR(cells[1]), canvas.renderAll());
          break;
        default:
          break;
      }
      console.log(gbr.src);

    });

    canvas2[i].renderAll();
  }

}

错误原因是由以下代码引起的

console.log(gbr.src);