Removing a Single Document from a Collection

You can delete a single document from a database by using the findAndRemove() method. This is very similar to the findAndModify() method in syntax and application. The following is the syntax for the findAndRemove() method:

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findAndRemove(query, sort, [options], callback)

The query parameter is a document that is used to identify the document to remove. The request matches the properties and values in the query parameter with the fields and values of the object, and only those that match the query parameter are modified.

The sort parameter is an array of [field, sort_order] pairs that specify which fields to sort on when finding the item to remove. sort_order is set to 1 for ascending and -1 for descending. The options parameter specifies the database change options described in Table 14.1. The first parameter of the callback function is an error, and the second parameter is the results of the document deletion.

Listing 14.8 shows how to delete a document by using the findAndRemove() method. Lines 9–18 implement the findAndRemove() method and the callback. The code searches on the items whose type is planetary. The sort order [['name', 1]] specifies to sort the items by name, in ascending order. Notice in the results shown in Figure 14.8 that the Cat's Eye entry was deleted, but the Helix entry was not because of the sort order.

Listing 14.8 doc_delete_one.js: Deleting single documents using findAndRemove()

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01 var MongoClient = require('mongodb').MongoClient;
02 MongoClient.connect("mongodb://localhost/", function(err, db) {
03   var myDB = db.db("astro");
04   myDB.collection("nebulae", function(err, nebulae){
05     nebulae.find(function(err, items){
06       items.toArray(function(err, itemArr){
07         console.log("Before Delete: ");
08         console.log(itemArr);
09         nebulae.findAndRemove({type:"Planetary"}, [['name', 1]],
10                               {w:1}, function(err, results){
11           console.log("Deleted: " + results);
12           nebulae.find(function(err, items){
13             items.toArray(function(err, itemArr){
14               console.log("After Delete: ");
15               console.log(itemArr);
16               db.close();
17             });
18           });
19         });
20       });
21     });
22   });
23 });

Figure 14.8 Deleting single documents by using findAndRemove().