面试题：CouchDB视图Map函数处理复杂嵌套数据的提取

Question

给定CouchDB文档结构如下{"user_info":{"name":"李四","contact":{"phone":"123456789","email":"[e-mail]"}},"orders":[{"order_id":"1","amount":100},{"order_id":"2","amount":200}]}。编写Map函数，提取出user_info中的name、email以及每个订单的order_id和amount，并合理组织输出格式以便后续Reduce操作使用。

Answer 1

function (doc) {
    if (doc.user_info && doc.orders) {
        var name = doc.user_info.name;
        var email = doc.user_info.contact.email;
        doc.orders.forEach(function(order) {
            emit(null, {
                name: name,
                email: email,
                order_id: order.order_id,
                amount: order.amount
            });
        });
    }
}