<u-picker @confirm="getcitydata" @cancel="show=false" keyName="name" :show="show" ref="uPicker"
            :columns="columns" @change="changeHandler"></u-picker>

changeHandler(e) {
                var that = this;
                const {
                    columnIndex,
                    index,
                    // 微信小程序无法将picker实例传出来，只能通过ref操作
                    picker = this.$refs.uPicker
                } = e
                if (columnIndex === 0) {
                    this.loading = true
                    console.log(e)
                    getcity(e.value[0].id, {
                        custom: {
                            auth: true
                        }
                    }).then(res => {
                        if (res.code == 0) {
                            console.log(res.data)
                            // that.columns.push(res.data)
                            picker.setColumnValues(1, res.data)
                            this.loading = false
                        }
                    }).catch(err => {

                    })
                    // 模拟网络请求
                    // uni.$u.sleep(1500).then(() => {
                    //  picker.setColumnValues(1, this.columnData[index])
                    //  this.loading = false
                    // })
                }
            },
            province() {
                var that = this
                that.columns = []
                province({}, {
                    custom: {
                        auth: true
                    }
                }).then(res => {
                    if (res.code == 0) {
                        console.log(res.data)
                        that.columns.push(res.data)
                        that.getcity(res.data[0])
                    }
                }).catch(err => {

                })
            },
            getcity(e) {
                var picker = this.$refs.uPicker
                getcity(e.id, {
                    custom: {
                        auth: true
                    }
                }).then(res => {
                    if (res.code == 0) {
                        console.log(res.data)
                        // that.columns.push(res.data)

                        picker.setColumnValues(1, res.data)
                        this.loading = false
                    }
                }).catch(err => {

                })
            },
            getcitydata(e) {
                console.log(e.value[1].name)
                console.log(e.value[1].id)
                this.formdata.cityname = e.value[1].name
                this.formdata.cityId = e.value[1].cityId
                this.show = false
            }