Updating Multiple Documents

The Model object provides an update() method that allows you to update multiple documents in a collection by using the update operators described in Table 14.2. The syntax for the update() method on Model objects is shown below:

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update(query, update, [options], [callback])

The query parameter defines the query used to identify which objects to update. The update parameter is an object that defines the update operation to perform on the document. The options parameter specifies the write preferences, and the callback parameter accepts an error as the first argument and the number of documents updated as the second.

A nice thing about updating at the model level is that you can use the Query object to define which objects should be updated. Listing 16.7 shows an example of using the update() method to update the size field of words that match the regex /grati.*/ to 0. Notice that line 11 defines an update object, but the code adds multiple query options onto the Query object before executing in line 14. Then the code makes another find() request, this time using the regex /grat.*/ to show that only what matches the update query actually changes. Figure 16.7 shows the output for Listing 16.7.

Listing 16.7 mongoose_update_many.js: Updating multiple documents in a collection by using Mongoose

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01 var mongoose = require('mongoose'),
02 var db = mongoose.connect('mongodb://localhost/words'),
03 var wordSchema = require('./word_schema.js').wordSchema;
04 var Words = mongoose.model('Words', wordSchema);
05 mongoose.connection.once('open', function(){
06   Words.find({word:/grati.*/}, function(err, docs){
07     console.log("Before update: ");
08     for (var i in docs){
09       console.log(docs[i].word + " : " + docs[i].size);
10     }
11     var query = Words.update({}, {$set: {size: 0}});
12     query.setOptions({multi: true});
13     query.where('word').regex(/grati.*/);
14     query.exec(function(err, results){
15       Words.find({word:/grat.*/}, function(err, docs){
16         console.log(" After update: ");
17         for (var i in docs){
18           console.log(docs[i].word + " : " + docs[i].size);
19         }
20         mongoose.disconnect();
21       });
22     });
23   });
24 });

Figure 16.7 Updating multiple documents in a collection by using Mongoose.