async onLoad(e) {

        await test.where({

            _id: 'dc65fe3e5e7cacea000cd5b91a9bbccd'

        }).update({

            data: {

                'arr.0': _.remove()

            }

        })

​

        test.where({

            _id: 'dc65fe3e5e7cacea000cd5b91a9bbccd'

        }).update({

            data: {

                'arr': _.pull(null)

            }

        })

    }

const db = wx.cloud.database()

const test = db.collection('test')

const _ = db.command

const $ = _.aggregate