一加5T  微信版本8.0.22 系统版本 android 10 基础库：2.42.2 【手动关闭蓝牙设备】 预览的时候，可以监听到状态变化，但是真机调试的时候，无法检测到状态变化 代码: // 连接蓝牙低功耗设备             wx.createBLEConnection({               deviceId: deviceId,               timeout: 10000,               success(res) {                 if (res.errCode == 0) {                   that.setData({                     isConnected: true                   });                 } else {                   wx.showModal({                     title: '提示',                     content: "不能正常对蓝牙设备进行连接",                     showCancel: false                   })                 }                 // 该方法回调中可以用于处理连接意外断开等异常情况                 wx.onBLEConnectionStateChange(function(r) {                   console.log(`device ${r.deviceId} state has changed, connected: ${r.connected}`)                   if (!r.connected) {                     that.setData({                       isFinded: false,                       isConnected: false,                       isFailed: true                     })                   }                 })                 // 停止搜索蓝牙设备                 wx.stopBluetoothDevicesDiscovery();                 clearInterval(timer)                 clearInterval(timer2)               },               fail(res) {                 wx.hideLoading();                 if (res.errCode == 10012) {                   wx.showModal({                     title: '提示',                     content: "连接超时",                     showCancel: false                   })                 }               },               complete() {                 wx.hideLoading();               }             })

{ "_id": 1, "A": [ 1, 2 ], "B": [ 1, 2 ] } { "_id": 2, "A": [ 1, 2 ], "B": [ 2, 1, 2 ] } { "_id": 3, "A": [ 1, 2 ], "B": [ 1, 2, 3 ] } { "_id": 4, "A": [ 1, 2 ], "B": [ 3, 1 ] } { "_id": 5, "A": [ 1, 2 ], "B": [ ] } { "_id": 6, "A": [ 1, 2 ], "B": [ {}, [] ] } { "_id": 7, "A": [ ], "B": [ ] } { "_id": 8, "A": [ ], "B": [ 1 ] } 下面的代码使用 [代码]setDifference[代码]，找到只存在于 [代码]B[代码] 中的数字： db.collection('test') .aggregate() .project({ isBOnly: $.setDifference(['$B', '$A']) }) .end() { "_id": 1, "isBOnly": [] } { "_id": 2, "isBOnly": [3] } { "_id": 3, "isBOnly": [3] } { "_id": 4, "isBOnly": [5] } { "_id": 5, "isBOnly": [] } { "_id": 6, "isBOnly": [{}, []] } { "_id": 7, "isBOnly": [] } { "_id": 8, "isBOnly": [1] } 测试结果和官方给出的结果不一样啊 https://developers.weixin.qq.com/miniprogram/dev/wxcloud/reference-sdk-api/database/command/aggregate/AggregateCommand.setDifference.html