Modify sub documents after matching parent document and sub document

问题

I have a scenario that I have a document inside which I have a sub collection. Now, I want to modify/update one of the sub document from the sub collection. I want to match the parent document and the sub document first before modifying the sub document. I am using mongoose/node.js and MongoDB

Here is my schema:-

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

var HostSchema   = new Schema({

    aid         :       String,
    cars        :       [{
                                carid : String,
                                status_code: Number                 
                        }]
});

module.exports = mongoose.model('Host', HostSchema);

Here is my code:-

router.route('/xxx/').post(function(req, res) {

    Host.findOne({
        _id : req.body.xid
    }, {
        cars : {
            carid : req.body.yid
        } 
    }, function(err, host) {
        if (err) {
            res.send(err);
        } else {
            // What to do?
        }
    });
});

I am able to print the whole sub collection but instead I want only one document matched from the sub collection should be printed. My goal is to modify the status_code field in the document of the sub collection

回答1:

My goal is to modify the status_code field in the document of the sub collection

You need to use the $ positional operator to update the sub document that matches the query.

Host.update({"_id":req.body.xid,"cars.carid":req.body.yid},
            {$set:{"cars.status_code":50}},function(err,numEffected){
            console.log(numEffected);
})

来源：https://stackoverflow.com/questions/27433032/modify-sub-documents-after-matching-parent-document-and-sub-document