Node.js MongoDB Select From
Select One
To select data from a table in MongoDB, we can use the
findOne() method.
The findOne() method returns the first
occurrence in the selection.
The first parameter of the findOne() method
is a query object. In this example we use an empty query object, which selects
all records in a table (but returns only the first record).
Example
Select the first record in the customers table:
var http = require('http');
var MongoClient = require('mongodb').MongoClient;
var url = "mongodb://localhost:27017/mydb";
MongoClient.connect(url, function(err, db) {
if (err) throw err;
db.collection("customers").findOne({}, function(err, result) {
if (err) throw err;
console.log(result.name);
db.close();
});
});
Run example »
Save the code above in a file called "demo_mongodb_findone.js" and run the file:
Run "demo_mongodb_findone.js"
C:\Users\Your Name>node demo_mongodb_findone.js
Which will give you this result:
Company Inc.
Select All
To select data from a table in MongoDB, we can also use the
find() method.
The find() method returns all
occurrences in the selection.
The first parameter of the find() method
is a query object. In this example we use an empty query object, which selects
all records in a table.
Example
Select the first record in the customers table:
var MongoClient = require('mongodb').MongoClient;
var url = "mongodb://localhost:27017/mydb";
MongoClient.connect(url, function(err, db) {
if (err) throw err;
db.collection("customers").find({}).toArray(function(err, result) {
if (err) throw err;
console.log(result);
db.close();
});
});
Run example »
Save the code above in a file called "demo_mongodb_find.js" and run the file:
Run "demo_mongodb_find.js"
C:\Users\Your Name>node demo_mongodb_find.js
Which will give you this result:
[
{ _id:
58fdbf5c0ef8a50b4cdd9a84 , name: 'John', address: 'Highway 71'},
{ _id:
58fdbf5c0ef8a50b4cdd9a85 , name: 'Peter', address: 'Lowstreet 4'},
{
_id: 58fdbf5c0ef8a50b4cdd9a86 , name: 'Amy',
address: 'Apple st 652'},
{ _id: 58fdbf5c0ef8a50b4cdd9a87 , name: 'Hannah', address:
'Mountain 21'},
{ _id: 58fdbf5c0ef8a50b4cdd9a88 , name: 'Michael', address: 'Valley 345'},
{ _id: 58fdbf5c0ef8a50b4cdd9a89 , name: 'Sandy', address: 'Ocean blvd 2'},
{
_id: 58fdbf5c0ef8a50b4cdd9a8a ,
name: 'Betty', address: 'Green Grass 1'},
{ _id:
58fdbf5c0ef8a50b4cdd9a8b , name: 'Richard',
address: 'Sky st 331'},
{ _id: 58fdbf5c0ef8a50b4cdd9a8c , name: 'Susan', address: 'One way
98'},
{ _id: 58fdbf5c0ef8a50b4cdd9a8d , name: 'Vicky', address: 'Yellow Garden 2'},
{ _id: 58fdbf5c0ef8a50b4cdd9a8e , name: 'Ben', address: 'Park Lane 38'},
{
_id: 58fdbf5c0ef8a50b4cdd9a8f , name: 'William',
address: 'Central st 954'},
{ _id: 58fdbf5c0ef8a50b4cdd9a90 , name: 'Chuck', address:
'Main Road 989'},
{ _id: 58fdbf5c0ef8a50b4cdd9a91 , name: 'Viola', address: 'Sideway
1633'}
]
The Result Object
As you can see from the result of the example above, the result can be converted into an array containing each row as an object.
To return e.g. the address of the third record, just refer to the third array object's address property:
Example
Return the address of the third record:
console.log(result[2].address]);
Which will produce this result:
Apple st 652
