CRUD（增删改查）

CRUD为数据库的最常见的4种基本操作，即增加(Create)、读取(Retrieve)(重新得到数据)、更新(Update)和删除(Delete)几个单词的首字母简写。主要被用在描述软件系统中数据库或者持久层的基本操作功能。

mongoose提供如下的crud方法

  • save
  • find | findOne
  • update
  • remove

下面我们使用user模型为例，给出具体例子

增加(Create)

文档

  1. Model#save(product,)
  3. @description Saves this document.
  5. Parameters:
  7. - product, <function(err, > Number)} [fn] optional callback
  9. Returns:
  10.     <Promise> Promise

具体代码

  1. const user = new User({
  2.   username: 'i5ting',
  3.   password: '0123456789'
  4. });
  6. user.save((err, u) => {
  7.     t.false(err);
  8.     t.is(u.username, 'i5ting');
  9. });

读取(Retrieve)

find：根据条件查询，返回的是数组

文档

  1. Model.find(conditions, [fields], [options], [callback])
  3. Finds documents
  5. Parameters:
  7. - conditions <Object>
  8. - [fields] <Object> optional fields to select
  9. - [options] <Object> optional
  10. - [callback] <Function>
  12. Returns:
  13.     <Query>

代码

  1. User.find({}, (err, docs) => {
  2.     t.false(err);
  3.     t.is(docs.length, 1);
  4.     t.is(docs[0].username, 'i5ting');
  5. });

findOne：根据条件查询，返回的是一条数据对象

文档

  1. Model.findOne([conditions], [fields], [options], [callback])
  3. Finds one document.
  5. Parameters:
  7. - [conditions] <Object>
  8. - [fields] <Object> optional fields to select
  9. - [options] <Object> optional
  10. - [callback] <Function>
  12. Returns:
  13.     <Query>

代码

  1. User.findOne({username: 'i5ting'}, (err, doc) => {
  2.     t.false(err);
  3.     t.is(doc.length, 1);
  4.     t.is(doc.username, 'i5ting');
  5. });

更新(Update)

findByIdAndUpdate：根据ID查找并更新

文档说明如下

  1. Model.findByIdAndUpdate(id, [update], [options], [callback])
  3. Issues a mongodb findAndModify update command by a documents id.
  5. show code
  7. Parameters:
  9. - id <ObjectId, HexId> an ObjectId or string that can be cast to one.
  10. - [update] <Object>
  11. - [options] <Object>
  12. - [callback] <Function>
  14. Returns:
  16.     <Query>

具体代码

  1.  User.findByIdAndUpdate(u._id, {
  2.     username: 'sang',
  3. }, (err, user) => {
  4.     t.false(err);
  5.     t.is(user.username, 'sang');
  6. });

findOneAndUpdate：根据查询条件查找并更新

  1. Model.findOneAndUpdate([conditions], [update], [options], [callback])
  3. Issues a mongodb findAndModify update command.
  5. Parameters:
  7. - [conditions] <Object>
  8. - [update] <Object>
  9. - [options] <Object>
  10. - [callback] <Function>
  12. Returns:
  13.     <Query>

具体代码

  1. User.findOneAndUpdate({
  2.     username: 'i5ting for update 2',
  3. }, {
  4.     username: 'sang',
  5. }, (err, user) => {
  6.     t.false(err);
  7.     t.is(user.username, 'sang');
  8. });

删除(Delete)

文档

  1. Model.remove(conditions, [callback])
  3. Removes documents from the collection.
  5. Parameters:
  7. - conditions <Object>
  8. - [callback] <Function>
  10. Returns:
  11.     <Promise> Promise

代码

  1. User.remove({username: 'i5ting for delete'}, (err, doc) => {
  2.     t.false(err);
  3.     t.is(doc.result.ok, 1);
  4.     t.is(doc.result.n, 1);
  5. });

执行测试

  1. $ cd db
  2. $ npm test
  4. > koa-db@1.0.0 test /Users/sang/workspace/17koa/book-source/db
  5. > ava crud -v
  8. 数据库连接成功
  9.   ✔ #save()
  10.   ✔ #find() return array
  11.   ✔ #findById() return array
  12.   ✔ #findOne() return user obj
  13.   ✔ #remove()
  14.   ✔ #findByIdAndUpdate()
  15.   ✔ #findOneAndUpdate()
  17.   6 tests passed

调试模式

调试模式是mongoose提供的一个非常实用的功能，用于查看mongoose模块对mongodb操作的日志，一般开发时会打开此功能，以便更好的了解和优化对mongodb的操作。

打开调试的核心代码是设置 debug 变量值为 true 即可

  1. var mongoose = require("mongoose");
  3. // 核心代码，是否开启测试
  4. mongoose.set('debug', true);
  6. var db = mongoose.connect("mongodb://127.0.0.1:27017/db_helloworld"); 
  8. db.connection.on("error", function (error) {  
  9.   console.log("数据库连接失败：" + error); 
  10. }); 
  12. db.connection.on("open", function () {  
  13.   console.log("数据库连接成功");
  14. });

执行测试如下

  1. $ cd db
  2. $ npm test
  4. > koa-db@1.0.0 test /Users/sang/workspace/17koa/book-source/db
  5. > ava crud -v
  8. 数据库连接成功
  9. Mongoose: users.remove({}) {}  
  10.   ✔ #save()
  11.   ✔ #find() return array
  12.   ✔ #findById() return array
  13.   ✔ #findOne() return user obj
  14.   ✔ #remove()
  15.   ✔ #findByIdAndUpdate()
  16.   ✔ #findOneAndUpdate()
  17. Mongoose: users.insert({ username: 'i5ting', password: '0123456789', _id: ObjectId("5734490640caa6d36906b8d4"), __v: 0 })   
  18. Mongoose: users.find({}) { fields: undefined }  
  19. Mongoose: users.findOne({ username: 'i5ting' }) { fields: undefined }  
  20. Mongoose: users.insert({ username: 'i5ting for delete', password: '0123456789', _id: ObjectId("5734490640caa6d36906b8d5"), __v: 0 })   
  21. Mongoose: users.insert({ username: 'i5ting for update 1', password: '0123456789', _id: ObjectId("5734490640caa6d36906b8d6"), __v: 0 })   
  22. Mongoose: users.insert({ username: 'i5ting for update 2', password: '0123456789', _id: ObjectId("5734490640caa6d36906b8d7"), __v: 0 })   
  23. Mongoose: users.remove({ username: 'i5ting for delete' }) {}  
  24. Mongoose: users.findAndModify({ _id: ObjectId("5734490640caa6d36906b8d6") }) [] { '$set': { username: 'sang' } } { new: false, upsert: false }
  25. Mongoose: users.findAndModify({ username: 'i5ting for update 2' }) [] { '$set': { username: 'sang' } } { new: false, upsert: false }
  27.   6 tests passed