树结构数据转换

function transformTreeData (flatArrs, parentItem) {

  var children = flatArrs.filter((item, index) => {
    return item.parentId == parentItem.id;
  }).map(record => {
    record.label = record.name
    record.value = record.id
    record.key = record.id
    return record
  });
  parentItem.children = children;
  for (var i in children) {
    this.transformTreeData(flatArrs, children[i]);
  }
  return parentItem.children
},

transformTreeData（array, {id: 0}）

array数组格式：
[{
　　id: 1, parentId: 0
}]