面试题：CouchDB中Map函数如何对嵌套数据结构进行高效转换

Question

假设在CouchDB中有一个文档，其数据结构为{"name":"John","hobbies":[{"name":"reading","books":["book1","book2"]}, {"name":"traveling","places":["city1","city2"]}]}，请编写一个Map函数，将其转换为以爱好名称为键，相关具体内容为值的新数据结构。

Answer 1

function(doc) {
  if (doc.hobbies) {
    doc.hobbies.forEach(function(hobby) {
      emit(hobby.name, hobby);
    });
  }
}