antd的表单验证如何验证图片上传

Question

const CreateForm = Form.create()(props => {
  const { modalVisible, form, handleAdd, handleModalVisible,formValues } = props;
  const { getFieldsValue, getFieldProps } = form;


  const okHandle = () => {
    form.validateFields((err, fieldsValue) => {
      console.log(err)
      console.log(fieldsValue)
      if (err) return;
      form.resetFields();
      handleAdd(fieldsValue);
    });
  };

  form.imgUrl = '';

  const onOkUpload = (res)=>{
    form.imgUrl = res.id||'';
    console.log(form.imgUrl)
  }

  const validator = (rule, value, callback) => {
    console.log(form.imgUrl)
    if(!form.imgUrl){
      callback('请上传图片')
    }
    callback()
  }
return (
    <Modal
      title="广告发布"
      visible={modalVisible}
      onOk={okHandle}
      onCancel={() => handleModalVisible()}
    >
      <FormItem labelCol={{ span: 5 }} wrapperCol={{ span: 15 }} label="广告图片">
        {form.getFieldDecorator('img', {
          valuePropName: 'fileList',
          getValueFromEvent:normFile,
        })(<UploadOne  onOk={onOkUpload} />)}
      </FormItem>
    </Modal>

(<UploadOne onOk={onOkUpload} />上传组件 ok吧url传出来,但是form 不知道如何验证