MongoDB
Setting Up MongoDB in c9
MongoDB is preinstalled in your workspace. To run MongoDB, run the following below (passing the correct parameters to it). Mongodb data will be stored in the folder data.
$ mkdir data
$ echo 'mongod --bind_ip=$IP --dbpath=data --nojournal --rest "$@"' > mongod
$ chmod a+x mongod
You can start mongodb by running the mongod script on your project root:
$ ./mongod
How can I customize the mongo shell prompt?
You can change the mongo shell prompt by setting the prompt variable.
This makes it possible to display additional information in the prompt.
Set prompt to any string or arbitrary JavaScript code that returns a string.
This example set the shell prompt to display the hostname and the database issued:
var host = db.serverStatus().host;
var prompt = function() { return db+"@"+host+"> "; }
The mongo shell prompt should now reflect the new prompt:
[email protected]>
MongoDB Documents
MongoDB documents are composed of field-and-value pairs. The value of a field can be any of the BSON data types, including other documents, arrays, and arrays of documents.
Queries
In MongoDB, the db.collection.find() method retrieves documents from a collection.
The db.collection.find() method returns a cursor
to the retrieved documents.
[~/local/src/javascript/mongoose/mongo-example-todos(develop)]$ mongo
MongoDB shell version: 3.0.2
connecting to: test
> show dbs
amazeriffic 0.078GB
chuchu 0.078GB
local 0.078GB
test 0.078GB
> use chuchu
switched to db chuchu
> show collections
cards
system.indexes
> db.cards.find({})
{ "_id" : ObjectId("5714999742131919ac3b0d5e"), "rank" : "ace", "suit" : "spades ♠", "chuchu" : [ { "a" : "hello", "b" : "world!", "_id" : ObjectId("5714999742131919ac3b0d5f") } ], "__v" : 0 }
{ "_id" : ObjectId("5714999742131919ac3b0d60"), "rank" : "2", "suit" : "hearts ♥", "chuchu" : [ { "a" : "hola", "b" : "mundo", "_id" : ObjectId("5714999742131919ac3b0d61") } ], "__v" : 0 }
{ "_id" : ObjectId("5714999742131919ac3b0d62"), "suit" : "clubs ♣", "rank" : "3", "chuchu" : [ { "a" : "hola", "b" : "mundo", "_id" : ObjectId("5714999742131919ac3b0d63") } ], "__v" : 0 }
You can include additional parameters to make the search more precise:
> db.cards.find({suit: /♥/})
{ "_id" : ObjectId("5714999742131919ac3b0d60"), "rank" : "2", "suit" : "hearts ♥", "chuchu" : [ { "a" : "hola", "b" : "mundo", "_id" : ObjectId("5714999742131919ac3b0d61") } ], "__v" : 0 }
If you want to only return a specific set of fields with the result,
you can include a map as the second parameter to find():
> db.cards.find({suit: /♥/}, {rank: true})
{ "_id" : ObjectId("5714999742131919ac3b0d60"), "rank" : "2" }
Note that the _id field will always be included by default unless you specifically state that you don't want it included.
We can use query operators to search for things that are within ranges. These include greater than (or equal to) and less than (or equal to).
> db.scores.find({cal: {$gt: 5, $lt: 8}})
{ "_id" : ObjectId("57150257224028006668b658"), "name" : "Nayla", "cal" : 6 }
{ "_id" : ObjectId("57150349224028006668b65f"), "name" : "Juan 6", "cal" : 6 }
{ "_id" : ObjectId("57150349224028006668b660"), "name" : "Juan 7", "cal" : 7 }
> db.scores.find({name: { $regex: /[eo]/}})
{ "_id" : ObjectId("57150232224028006668b656"), "name" : "Pedro", "cal" : 5 }
{ "_id" : ObjectId("57150257224028006668b657"), "name" : "Antonio", "cal" : 5 }
Insertando Datos
An interesting thing to note is that if you use use on a database that doesn't exist, one is created automatically.
> use tutu
switched to db tutu
> show dbs
amazeriffic 0.078GB
chuchu 0.078GB
local 0.078GB
test 0.078GB
> show collections
> db.scores.insert({name: "Juana", cal: 10})
WriteResult({ "nInserted" : 1 })
> show collections
scores
system.indexes
> show dbs
amazeriffic 0.078GB
chuchu 0.078GB
local 0.078GB
test 0.078GB
tutu 0.078GB
...
> db.scores.insert([{name: "Antonio", cal: 5}, {name: "Nayla", cal: 6}])
> db.scores.find({})
{ "_id" : ObjectId("57150162224028006668b655"), "name" : "Juana", "cal" : 10 }
{ "_id" : ObjectId("57150232224028006668b656"), "name" : "Pedro", "cal" : 5 }
{ "_id" : ObjectId("57150257224028006668b657"), "name" : "Antonio", "cal" : 5 }
{ "_id" : ObjectId("57150257224028006668b658"), "name" : "Nayla", "cal" : 6 }
> for(var i=0;i<10;i++) { db.scores.insert({name: "Juan "+i, cal: i}) }
> db.scores.find({})
{ "_id" : ObjectId("57150162224028006668b655"), "name" : "Juana", "cal" : 10 }
{ "_id" : ObjectId("57150232224028006668b656"), "name" : "Pedro", "cal" : 5 }
{ "_id" : ObjectId("57150257224028006668b657"), "name" : "Antonio", "cal" : 5 }
{ "_id" : ObjectId("57150257224028006668b658"), "name" : "Nayla", "cal" : 6 }
{ "_id" : ObjectId("57150349224028006668b659"), "name" : "Juan 0", "cal" : 0 }
{ "_id" : ObjectId("57150349224028006668b65a"), "name" : "Juan 1", "cal" : 1 }
{ "_id" : ObjectId("57150349224028006668b65b"), "name" : "Juan 2", "cal" : 2 }
{ "_id" : ObjectId("57150349224028006668b65c"), "name" : "Juan 3", "cal" : 3 }
{ "_id" : ObjectId("57150349224028006668b65d"), "name" : "Juan 4", "cal" : 4 }
{ "_id" : ObjectId("57150349224028006668b65e"), "name" : "Juan 5", "cal" : 5 }
{ "_id" : ObjectId("57150349224028006668b65f"), "name" : "Juan 6", "cal" : 6 }
{ "_id" : ObjectId("57150349224028006668b660"), "name" : "Juan 7", "cal" : 7 }
{ "_id" : ObjectId("57150349224028006668b661"), "name" : "Juan 8", "cal" : 8 }
{ "_id" : ObjectId("57150349224028006668b662"), "name" : "Juan 9", "cal" : 9 }
Actualizando Datos
To update a record, use the update() function, but include a find
query as the first parameter and use the $setoperator in the second parameter:
> db.scores.update({name: /juan 1/i}, {$set: {cal: 5}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.scores.find({name: /juan 1/i})
{ "_id" : ObjectId("57150349224028006668b65a"), "name" : "Juan 1", "cal" : 5 }
> db.scores.update({name: /juan [5-9]/i}, {$set: {cal: 4.5}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.scores.find({name: /juan [5-9]/i})
{ "_id" : ObjectId("57150349224028006668b65e"), "name" : "Juan 5", "cal" : 4.5 }
{ "_id" : ObjectId("57150349224028006668b65f"), "name" : "Juan 6", "cal" : 6 }
{ "_id" : ObjectId("57150349224028006668b660"), "name" : "Juan 7", "cal" : 7 }
{ "_id" : ObjectId("57150349224028006668b661"), "name" : "Juan 8", "cal" : 8 }
{ "_id" : ObjectId("57150349224028006668b662"), "name" : "Juan 9", "cal" : 9 }
Es necesario especificar $set de lo contrario el segundo argumento es interpretado como argumento
de sustitución:
> db.scores.update({name: /juan 2/i}, {cal: 8})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.scores.find({cal: {$eq: 8}})
{ "_id" : ObjectId("57150349224028006668b65b"), "cal" : 8 }
{ "_id" : ObjectId("57150349224028006668b661"), "name" : "Juan 8", "cal" : 8 }
the second parameter in the update() function is actually the new version of the complete document.
Since you only wanted to update the cal field, what actually happened was that the document that was found was replaced with the new version that consists of only the cal field.
To reiterate, the reason this happens at all is because with NoSQL such as MongoDB, the document does not have a set number of fields (as a relational database does).
When you want to update a document, but the document itself may or may not exist.
Pass {upsert: true} as the third parameter to the update() function:
> db.scores.update({name: "Juan 10"}, {name: "Juan 10", cal:10})
WriteResult({ "nMatched" : 0, "nUpserted" : 0, "nModified" : 0 })
> db.scores.update({name: "Juan 10"}, {name: "Juan 10", cal:10}, {upsert: true})
WriteResult({
"nMatched" : 0,
"nUpserted" : 1,
"nModified" : 0,
"_id" : ObjectId("57151147c5b206ceaf9ada5a")
})
> db.scores.find({cal: 10, name: /10/})
{ "_id" : ObjectId("57151147c5b206ceaf9ada5a"), "name" : "Juan 10", "cal" : 10 }
Suprimiendo Datos
Deleting documents works almost exactly like find(), except instead of finding and returning results, it deletes those documents that match the search criteria:
> db.scores.remove({ name: 'Maria' })
If you want the nuclear option, you can use the drop() function, which will remove
every document in a collection:
> db.scores.drop()
MongoDB en Node.js
Empezando
[~/src/mongodb/getting-started]$ curl https://raw.githubusercontent.com/mongodb/docs-assets/primer-dataset/primer-dataset.json -o primer-dataset.json
[~/DSI/EXAMENES/170516(master)]$ mongod
2016-05-15T11:42:19.621+0100 I JOURNAL [initandlisten] journal dir=/data/db/journal
2016-05-15T11:42:19.625+0100 I JOURNAL [initandlisten] recover : no journal files present, no recovery needed
2016-05-15T11:42:19.678+0100 I JOURNAL [durability] Durability thread started
...
[~/src/mongodb/getting-started]$ mongoimport --db test --collection restaurants --drop --file primer-dataset.json
2016-05-15T11:42:58.735+0100 connected to: localhost
2016-05-15T11:42:58.736+0100 dropping: test.restaurants
2016-05-15T11:43:00.559+0100 imported 25359 documents
The mongoimport connects to a mongod instance running on localhost on port number 27017.
To import data into a mongod instance running on a different host or port, specify the hostname or port by including the --host and the --port options in your mongoimport command.
[~/src/mongodb/getting-started]$ npm install mongodb
[~/src/mongodb/getting-started]$ node hellomongo.js | less
Connected correctly to server.
Inserted a document into the restaurants collection.
{ _id: ObjectID { _bsontype: 'ObjectID', id: 'W8R³÷mWG\u001dÇ0-' },
address:
{ building: '2780',
coord: [ -73.98241999999999, 40.579505 ],
street: 'Stillwell Avenue',
zipcode: '11224' },
borough: 'Brooklyn',
cuisine: 'American ',
grades:
[ { date: Tue Jun 10 2014 01:00:00 GMT+0100 (WEST),
grade: 'A',
score: 5 },
{ grade: 'A',
score: 7,
date: Wed Jun 05 2013 01:00:00 GMT+0100 (WEST) },
{ score: 12,
date: Fri Apr 13 2012 01:00:00 GMT+0100 (WEST),
grade: 'A' },
{ date: Wed Oct 12 2011 01:00:00 GMT+0100 (WEST),
grade: 'A',
score: 12 } ],
name: 'Riviera Caterer',
restaurant_id: '40356018' }
{ _id: ObjectID { _bsontype: 'ObjectID', id: 'W8R³÷mWG\u001dÇ0.' }
var MongoClient = require('mongodb').MongoClient;
var assert = require('assert');
var url = 'mongodb://localhost:27017/test';
MongoClient.connect(url, function(err, db) {
assert.equal(null, err);
console.log("Connected correctly to server.");
db.close();
});
var insertDocument = function(db, callback) {
db.collection('restaurants').insertOne( {
"address" : {
"street" : "2 Avenue",
"zipcode" : "10075",
"building" : "1480",
"coord" : [ -73.9557413, 40.7720266 ]
},
"borough" : "Manhattan",
"cuisine" : "Italian",
"grades" : [
{
"date" : new Date("2014-10-01T00:00:00Z"),
"grade" : "A",
"score" : 11
},
{
"date" : new Date("2014-01-16T00:00:00Z"),
"grade" : "B",
"score" : 17
}
],
"name" : "Vella",
"restaurant_id" : "41704620"
}, function(err, result) {
assert.equal(err, null);
console.log("Inserted a document into the restaurants collection.");
callback();
});
};
MongoClient.connect(url, function(err, db) {
assert.equal(null, err);
insertDocument(db, function() {
db.close();
});
});
var findRestaurants = function(db, callback) {
var cursor =db.collection('restaurants').find( );
cursor.each(function(err, doc) {
assert.equal(err, null);
if (doc != null) {
console.dir(doc);
} else {
callback();
}
});
};
MongoClient.connect(url, function(err, db) {
assert.equal(null, err);
findRestaurants(db, function() {
db.close();
});
});