Removing Multiple Documents

The Model object’s remove() method allows you to delete multiple documents in a collection by using a single call to the database. The syntax for the remove() method on Model objects is shown below:

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

The query parameter defines the query used to identify which objects to delete. The options parameter specifies the write preferences, and the callback parameter accepts an error as the first argument and the number of documents deleted as the second.

A nice thing about deleting at the model level is that you delete multiple documents in the same operation, saving the overhead of multiple requests. Also, you can use the Query object to define which objects to update.

Listing 16.9 shows an example of using the remove() method to delete words that match the regex /grati.*/ expression. Notice that the code pipes multiple query options onto the Query object before line 13 executes it. The listing displays the number of documents removed, and then another find() request is made, this time using the regex /grat.*/ to show that only those matching the remove query actually are deleted. Figure 16.9 shows the output for Listing 16.9.

Listing 16.9 mongoose_remove_many.js: Deleting 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:/grat.*/}, function(err, docs){
07     console.log("Before delete: ");
08     for (var i in docs){
09       console.log(docs[i].word);
10     }
11     var query = Words.remove();
12     query.where('word').regex(/grati.*/);
13     query.exec(function(err, results){
14       console.log(" %d Documents Deleted.", results);
15       Words.find({word:/grat.*/}, function(err, docs){
16         console.log(" After delete: ");
17         for (var i in docs){
18           console.log(docs[i].word);
19         }
20         mongoose.disconnect();
21       });
22     });
23   });
24 });

Figure 16.9 Deleting multiple documents in a collection by using Mongoose.