面试题：CouchDB中嵌套数据的基础查询问题

Question

假设在CouchDB中有一个文档，结构如下：{"_id":"example_doc","name":"John","hobbies":[{"name":"reading","books":["book1","book2"]},{"name":"traveling","places":["Paris","London"]}]}。请编写一个CouchDB视图函数，用于查询所有爱好为reading的文档，并返回相关的书籍列表。

Answer 1

function (doc) {
  if (doc.hobbies) {
    doc.hobbies.forEach(function (hobby) {
      if (hobby.name === "reading") {
        emit(doc._id, hobby.books);
      }
    });
  }
}