选择或者默认值设置上也不显示日期，是空白的

<picker mode="date" value="{{account.ubirth}}" start="1900-01-01" end="2019-09-01" bindchange="bindDateChange">

    <view class="weui-input">{{account.ubirth}}</view>

</picker>

bindDateChange: function (e) {

    var account = this.data.account;

    account.ubirth = e.detail.value;

    this.setData({

    account: account

    });

}