如何在mongo中更新数据

Question

So I am currently working on a project with mongodb and nodejs and I was wondering, how can you update data in mongodb via nodejs? My problem is that I want to keep the old data and add new. For example, here is the data currently in my mongodb

{
    "_id" : ObjectId("5a1c0c1c3b147ec2e31cceb3"), 
    "event_id" : "1", 
    "event_medium" : "null", 
    "event_tags" : ["#JustTesting"]
}

So I want to add new data to the event_tags array and still keep the old data.

So for example the end result would be this:

{
    "_id" : ObjectId("5a1c0c1c3b147ec2e31cceb3"), 
    "event_id" : "1",
    "event_medium" : "null", 
    "event_tags" : ["#JustTesting", "#Test", "#Something"]
}

Answer 1

Your starting point is the Update function in CRUD (Create,Read, Update, Delete) operations in Mongodb.

Your node program should have among others the update function where you set the _id field you want to update and load the content fields to be update in 'data' for example as below:

myModel.prototype.update = function (_id, data, callback) {
    const query = { _id: this.mongo.ObjectId(_id) };
    debug(' update:' + JSON.stringify(query));
    this.mongo.collection('mycollection').update(query, data, callback);
};

This piece of code should be put in your Model, if you use MVC pattern.

There is a lot to go. Honestly I recommend a more deep tutorial like parts 3 and 4 of this one for nodejs and Mongoose (mongo db driver): MDN tutorial for mongo/node/express

Answer 2

I assume you are using mongoose..

    eventModel.findOne({event_id:1 },
        function(err, eventObj){
        if(err){
          //handle error
        } else { 
          if(eventObj === null) {
            //event doesnot exist       
          }
          var tagList = eventObj.event_tags; 
          tagList.push('new_tag1');
          tagList.push('new_tag2');
          eventObj.event_tags = tagList;
          eventObj.save(function(err){
            if(err){
              //handle error
            } else {
              //success
            }
          })

Answer 3

You should use the update function of MongoDB for that. MongoDB knows different update operators , in your case you may use $push or $pushAll (the second is deprecated):

update one after the other with $push

YourCollection.update({ _id: 'xxx' }, { $push: { event_tags: '#Test' } });
YourCollection.update({ _id: 'xxx' }, { $push: { event_tags: '#Something' } });

or both at once with $pushAll (deprecated now)

YourCollection.update({ _id: 'xxx' }, { $pushAll: { event_tags: ['#Test', '#Something'] } });

To interact with MongoDB form your NodeJS app, I would use a library like this one .