node.js - Mongoose :将元素插入或替换到数组中

Question

我正在使用 Mongoose (node.js 中的 MongoDB)，阅读此答案后:

• Replace value in array

我还有一个问题:

• 是否可以在同一句话中做:将元素插入数组或如果该元素存在于数组中则替换？

也许是这样的？ (示例不起作用)

    Model.findByIdAndUpdate(id,
    {
     $pull: {"readers": {user: req.user.id}},
     $push:{"readers":{user: req.user.id, someData: data}}
    },{multi:true},callback)

消息错误:

errmsg: '异常:无法同时更新\'readers\' 和\'readers\'

引用:

• https://stackoverflow.com/a/15975515/4467741

谢谢!

Answer 1

在单个请求中根本不允许对同一属性路径进行多个操作，主要原因是操作本身在文档更新时引擎分配它们的方式中“没有特定顺序”，因此是应该报告为错误的冲突。

所以对此的基本抽象是您要执行“两个”更新操作，一个是“替换”存在的元素，另一个是“推送”不存在的新元素。

最好的实现方式是使用 "Bulk" operations ，虽然“技术上”仍然是“两个”更新操作，但无论满足哪个条件，它都只是一个“单个”请求和响应:

var bulk = Model.collection.initializeOrderedBulkOp();

bulk.find({ "_id": id, "readers.user": req.user.id }).updateOne({
    "$set": { "readers.$.someData": data } }
});

bulk.find({ "_id": id, "readers.user": { "$ne": req.user.id } }).updateOne({
    "$push": { "readers": { "user": req.user.id, "someData": data } }
});

bulk.execute(function(err,result) {
    // deal with result here
});

如果您真的“需要”结果中的更新对象，那么按照未找到数组元素的逻辑，这真的变成了“可能的”多重请求:

Model.findOneAndUpdate(
    { "_id": id, "readers.user": req.user.id },
    { "$set": { "readers.$.someData": data } },
    { "new": true },
    function(err,doc) {
        if (err) // handle error;
        if (!doc) {
            Model.findOneAndUpdate(
                { "_id": id, "readers.user": { "$ne": req.user.id } },
                { "$push": { "readers":{ "user": req.user.id, "someData": data } } },
                { "new": true },
                function(err,doc) {
                    // or return here when the first did not match
                }
            );
        } else {
            // was updated on first try, respond
        }
    }
);

再次使用您喜欢的方法，不使用类似 async 的嵌套回调。或某些描述的嵌套 promise 结果，以避免一个 Action 固有的基本缩进蔓延依赖于另一个 Action 的结果。

如果您真的需要，“批量”执行更新然后再“获取”数据基本上可能更有效。

---

完整 list

var async = require('async'),
    mongoose  = require('mongoose')
    Schema = mongoose.Schema;

mongoose.connect('mongodb://localhost/test');

var userSchema = new Schema({
  name: String
});

var dataSchema = new Schema({
  user: { type: Schema.Types.ObjectId, ref: 'User' },
  someData: String
},{ "_id": false });

var testSchema = new Schema({
  name: String,
  readers: [dataSchema]
});

var User = mongoose.model( 'User', userSchema ),
    Test = mongoose.model( 'Test', testSchema );

var userId = null,
    id = null;

async.series(

  [
    // Clean models
    function(callback) {
      async.each([User,Test],function(model,callback) {
        model.remove({},callback);
      },callback);
    },

    // Create a user
    function(callback) {
      User.create({ name: 'bill' },function(err,user) {
        userId = user._id;
        callback(err);
      });
    },

    function(callback) {
      Test.create({ name: 'Topic' },function(err,topic) {
        id = topic._id;
        console.log("initial state:");
        console.log(topic);
        callback(err);
      });
    },

    // 1st insert array 2nd update match 1 modified
    function(callback) {
      var bulk = Test.collection.initializeOrderedBulkOp();

      bulk.find({ "_id": id, "readers.user": userId }).updateOne({
        "$set": { "readers.$.someData": 1 }
      });

      bulk.find({ "_id": id, "readers.user": { "$ne": userId }}).updateOne({
        "$push": { "readers": { "user": userId, "someData": 1 } }
      });

      bulk.execute(function(err,result) {
        if (err) callback(err);
        console.log("update 1:");
        console.log(JSON.stringify( result, undefined, 2));
        Test.findById(id,function(err,doc) {
          console.log(doc);
          callback(err);
        });
      });
    },

    // 2nd replace array 1st update match 1 modified
    function(callback) {
      var bulk = Test.collection.initializeOrderedBulkOp();

      bulk.find({ "_id": id, "readers.user": userId }).updateOne({
        "$set": { "readers.$.someData": 2 }
      });

      bulk.find({ "_id": id, "readers.user": { "$ne": userId }}).updateOne({
        "$push": { "readers": { "user": userId, "someData": 2 } }
      });

      bulk.execute(function(err,result) {
        if (err) callback(err);
        console.log("update 2:");
        console.log(JSON.stringify( result, undefined, 2));
        Test.findById(id,function(err,doc) {
          console.log(doc);
          callback(err);
        });
      });
    },

    // clear array
    function(callback) {
      Test.findByIdAndUpdate(id,
        { "$pull": { "readers": {} } },
        { "new": true },
        function(err,doc) {
          console.log('cleared:');
          console.log(doc);
          callback(err);
        }
      );
    },

    // cascade 1 inner condition called on no array match
    function(callback) {
      console.log('update 3:');
      Test.findOneAndUpdate(
        { "_id": id, "readers.user": userId },
        { "$set": { "readers.$.someData": 1 } },
        { "new": true },
        function(err,doc) {
          if (err) callback(err);
          if (!doc) {
            console.log('went inner');
            Test.findOneAndUpdate(
              { "_id": id, "readers.user": { "$ne": userId } },
              { "$push": { "readers": { "user": userId, "someData": 1 } } },
              { "new": true },
              function(err,doc) {
                console.log(doc)
                callback(err);
              }
            );
          } else {
            console.log(doc);
            callback(err);
          }
        }
      );
    },

    // cascade 2 outer condition met on array match
    function(callback) {
      console.log('update 3:');
      Test.findOneAndUpdate(
        { "_id": id, "readers.user": userId },
        { "$set": { "readers.$.someData": 2 } },
        { "new": true },
        function(err,doc) {
          if (err) callback(err);
          if (!doc) {
            console.log('went inner');
            Test.findOneAndUpdate(
              { "_id": id, "readers.user": { "$ne": userId } },
              { "$push": { "readers": { "user": userId, "someData": 2 } } },
              { "new": true },
              function(err,doc) {
                console.log(doc)
                callback(err);
              }
            );
          } else {
            console.log(doc);
            callback(err);
          }
        }
      );
    }

  ],
  function(err) {
    if (err) throw err;
    mongoose.disconnect();
  }

);

输出:

initial state:
{ __v: 0,
  name: 'Topic',
  _id: 55f60adc1beeff6b0a175e98,
  readers: [] }
update 1:
{
  "ok": 1,
  "writeErrors": [],
  "writeConcernErrors": [],
  "insertedIds": [],
  "nInserted": 0,
  "nUpserted": 0,
  "nMatched": 1,
  "nModified": 1,
  "nRemoved": 0,
  "upserted": []
}
{ _id: 55f60adc1beeff6b0a175e98,
  name: 'Topic',
  __v: 0,
  readers: [ { user: 55f60adc1beeff6b0a175e97, someData: '1' } ] }
update 2:
{
  "ok": 1,
  "writeErrors": [],
  "writeConcernErrors": [],
  "insertedIds": [],
  "nInserted": 0,
  "nUpserted": 0,
  "nMatched": 1,
  "nModified": 1,
  "nRemoved": 0,
  "upserted": []
}
{ _id: 55f60adc1beeff6b0a175e98,
  name: 'Topic',
  __v: 0,
  readers: [ { user: 55f60adc1beeff6b0a175e97, someData: '2' } ] }
cleared:
{ _id: 55f60adc1beeff6b0a175e98,
  name: 'Topic',
  __v: 0,
  readers: [] }
update 3:
went inner
{ _id: 55f60adc1beeff6b0a175e98,
  name: 'Topic',
  __v: 0,
  readers: [ { someData: '1', user: 55f60adc1beeff6b0a175e97 } ] }
update 3:
{ _id: 55f60adc1beeff6b0a175e98,
  name: 'Topic',
  __v: 0,
  readers: [ { someData: '2', user: 55f60adc1beeff6b0a175e97 } ] }