微信小程序picker下拉绑定数据

页面部分，wxml中写入以下代码

<picker mode = "selector" bindchange="bindPickerChange" value="{{project[idx].id}}" range="{{project}}" range-key="{{'val'}}">
    <view class="picker picker1">
      {{project[idx].val}}<text class='down'></text>
    </view>
</picker>

js部分

data: {
    idx:0,
    project:[
      {
        id: 0,
        val: '互联网'
      },
      {
        id: 1,
        val: '建材'
      },
      {
        id: 2,
        val: '法律'
      },
    ]
},
// 改变下拉选项
bindPickerChange: function (event){
    this.setData({   //给变量赋值
      idx: event.detail.value,
    })
},

let id = this.data.project[this.data.idx].id