2. Whoami
Ynon Perek
http://ynonperek.com
ynon@ynonperek.com
Thursday, January 31, 13
3. Agenda
MongoDB Overview
Mongo Test Drive
Mongo Data Model
CRUD Operations
Working With Files
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4. MongoDB Overview
Data Store for
JSON Objects
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5. MongoDB Overview
Data Store for
JSON Objects
{
“Name” : “Rose Tyler”
}
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6. JSON Objects
A JSON Object is a collection of key/value pairs
Keys are simple strings
Values can be: Numbers, Strings, Arrays, Other Objects,
and more
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23. Connecting To The DB
There are two options to work with your new DB
You can use the web console
You can use the command line console
Let’s start with the web.
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24. Demo: Creating Documents
Create a few
documents on the web
console
Update the data
Delete some of them
Search by fields
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25. Mongo Data Model
Let’s model A blog post
in a blog app
What’s The Data ?
How Should You Save
It ?
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28. Lab
Create a DB for musical info
Create a collection called albums
Add info for 3 albums you like, including:
Album Name, Artist, Tracks, Release Date, Genres
Tracks is an array of objects
Genres is an array of strings
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29. CRUD Operations
Create, Read, Update and Destroy Data
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30. Mongo CRUD
Create is called insert
Read is called find
Update is called update
Destroy is called remove
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31. Mongo CRUD
From a developer’s perspective, MongoDB operations are
the same through the driver and through the console
In both cases, operations look like function calls or
method invocations
We’ll use mongo shell for the rest of this chapter
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32. Inserting Data
Use the command insert or save to insert a new object
db.collection.insert( obj );
db.collection.insert( array );
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33. Inserting Data
Inserting to a new collection creates the collection
Inserting an object with an _id key, it is used as the
object’s id (and must be unique).
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34. Reading Data
find and findOne perform read operations
Both take a query
find returns a cursor
findOne returns an object Optional: Fields to
fetch
db.collection.find( <query>, <projection> )
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35. Query Document
An empty (or missing) query document returns
everything
db.collection.find({})
db.collection.find()
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36. Query Document
Each key/value pair in the query document imposes a
condition on the results (objects that match).
db.movies.find({ “genre” : “indie” });
db.books.find({“pages” : { “$gt” : 100 }});
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37. Query Document
Query Object
Each key/value pair in the query document imposes a
condition on the results (objects that match).
db.movies.find({ “genre” : “indie” });
db.books.find({“pages” : { “$gt” : 100 }});
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38. Query Document
A compound query means a logical AND on the
conditions.
db.inventory.find(
{
“type” : “snacks”,
“available” : { “$lt” : 10 }
});
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39. Quiz: What Is Returned
from alterego publisher
Bruce
{ Earth DC
Wayne
“publisher” :
“DC”
} Peter
Earth Marvel
Parker
Krypton Clark Kent DC
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40. Quiz: What Is Returned
from alterego publisher
{ Bruce
“publisher” : Earth DC
Wayne
“DC”,
“from” :
“Earth” Peter
Earth Marvel
} Parker
Krypton Clark Kent DC
Thursday, January 31, 13
41. More Queries
You can use “$or” to have an OR expression
{
“$or” : [
{ “type” : “food” },
{ “type” : “drinks” }
]
}
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42. Sub Documents
If your document has sub-documents, it’s possible to
query by a full sub document or look for a partial match
Full sub-document query means subdocument is exactly
as specified in the query
Example:
{ ISBN : { “ISBN-10” : “1906465592”,
“ISBN-13” : “978-1906465599” }}
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43. Sub Documents
A partial query matches all objects that have at least the
required field (but may contain more)
Example:
{
“language.primary” : “english”
}
Value of language is an object, and it has a field called
primary
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44. Arrays
You can use an exact array match by providing the full
array in the query
Example:
{
tags : [ “funny”, “cute”, “cats” ]
}
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45. Arrays
You can query for an array that has at least one element
matching the query
Example:
{ “tags” : “funny” }
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46. Arrays
If you have a subdocument as the element of an array,
it’s possible to query by its fields using the dot notation.
Examples:
{ “tracks.4.name” : “Rose Mary Stretch” }
{ “tracks.name” : “Rose Mary Stretch” }
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47. Query Operators
Complex queries are performed with special operators.
These are reserved words starting with a $
Some of them: $gt, $gte, $lt, $lte, $ne, $in, $nin, $all,
$or, $not
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48. Comparator Queries
Value for key a is greater than 10
{ “a” : { “$gt” : 10 }}
Value for key b is not 7
{ “b” : { “$ne” : 7 }}
Value for key name is greater (dictionary sort) than
‘bird’
{ “name” : { “$gt” : “bird” }}
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49. Queries: $in, $nin
Use $in to specify a choice from multiple options
Value for grade is 85, 90 or 100
{ “grade” : { “$in” : [ 85, 90, 100 ] } }
Value for fruit is neither apple nor banana
{ “fruit” : { “$nin” : [“apple”, “banana” ] } }
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50. Quiz: What Is Selected
{ “reads” : { “$gt” : 10 },
“author” : { “$nin” : [“admin”, “manager”, “boss” ] } }
author reads title
How To Use
admin 99
Mongo
How To Make
Joe 120
Money
Windows
Jim 8
Manual
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51. Queries: $all
Select objects with array containing all elements
Example:
{ “tags” : { “$all” : [ “funny”, “cats” ] } }
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52. More Query Operators
“$size” - array has a specific number of elements
“$exists” - field present or missing
Example:
{ “friends” : { “$size” : 7 } }
{ “producer” : { “$exists” : false } }
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53. Aggregation
count() - returns how many objects found
distinct() - returns all distinct values for a key
Example:
db.posts.distinct( “tags” )
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56. Lab
Using the previously defined musical DB. Query for:
Albums released after/before 2008
Albums with 7 tracks
Albums by a specific genre
Albums by a specific track name
Display ALL different genres in the DB
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57. Update
Update operations modify existing data in the DB
Mongo supports two update commands:
update() and save()
Update is the more general (and complex)
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58. Update
The general form for update is:
db.collection.update(
<query>, <update>, <options> )
Which Entries What to do with
to update them
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59. Update
The second argument to update() is an operator object
It tells update what to do with the data
Some keys you can use: “$set”, “$inc” “$push”,
“$pushAll”, “$addToSet”, “$pop”, “$pull”, “$pullAll”
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60. Update: set
$set modifies a value or add a new value
Example:
db.posts.update(
{ title: “Why Is Your Cat Unhappy” },
{ $set : { “archived” : true } }
);
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61. Quiz: $set
What happens here ?
db.cats.update(
{ color: “white” },
{ “$set” : { “owners” : [“John”, “Jim”] } }
);
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62. Quiz: $set
Update owners array of the first cat with white color
If you want to update all objects, use multi
db.cats.update(
{ color: “white” },
{ “$set” : { “owners” : [“John”, “Jim”] } }
{ multi : true }
);
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63. Update: inc
$inc increases a numeric value
Example:
{ “$inc” : { “age” : 11 } }
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64. Quiz: $inc
What happens here ?
db.songs.update(
{ “title” : “Killing Lies” },
{ “$inc” : { “plays” : 1 } }
);
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65. Update: push and pushAll
push() and pushAll() add items to an existing array
If they array did not exists, it is created
Example:
db.creatures.update(
{ name: “The Doctor” },
{ “$push” : { companions : “Rose Tyler” } }
)
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66. Update: addToSet
The $addToSet adds a new item only if it wasn’t already
in the array
Example:
{ “$addToSet” : { “tags” : “funny” } }
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67. Update: pop
pop removes items of an array
Use a value of 1 to remove the last element
Use a value of -1 to remove the first element
Example:
{ “$pop” : { “companions” : 1 } }
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68. Update: pull
Remove a specific item from an array.
Can use $pullAll to remove all matching elements
Example:
{ “$pull” : { “companions” : “Rose Tyler” } }
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69. Updating with save()
The second update operation is save()
takes a document:
If the document has an id - update it
If not, insert it to the DB
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70. Deleting Data
remove() deletes objects from a collection
Takes a query and possibly a <justOne> arguments
Examples:
db.posts.remove({ “author” : “Father Angelo” })
db.music.remove({ “genres” : “pop” })
db.posts.remove({ “tags” : “funny” }, 1 );
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72. Lab
From the previous music database:
Add a new album with 4 tracks
Add a new track to that new album
Set property “plays” on all albums to 6
Increase it by 4 only for “indie” albums
Delete all “indie” music
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73. Mongoose
MongoDB + Node.JS
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74. What’s That
An Object Relational Mapper for Node.JS
Handles gory details so you don’t have to
Fat Models
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75. Agenda
Hello Mongoose
Schema and Data Types
Custom Validators
Querying Data
Poor Man’s Joins (Populate)
Mongoose Plugins
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76. Online Resources
http://mongoosejs.com/
https://github.com/LearnBoost/mongoose
http://www.youtube.com/watch?v=4fQsDiioj3I
irc: #mongoosejs on freenode
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77. Hello Mongoose
var mongoose = require('mongoose');
mongoose.connect('localhost', 'test');
var schema = mongoose.Schema({ name: 'string' });
var Cat = mongoose.model('Cat', schema);
var kitty = new Cat({ name: 'Zildjian' });
kitty.save(function (err) {
if (err) // ...
console.log('meow');
});
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78. Mongoose Objects
Schema Schema
Model Model Model
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79. Mongoose Objects
var mongoose = require('mongoose');
mongoose.connect('localhost', 'test'); { name: String}
var schema = mongoose.Schema(
{ name: 'string' });
Cat
var Cat = mongoose.model(
'Cat', schema);
var kitty = new Cat( kitty
{ name: 'Zildjian' });
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80. Schema Definitions
new Schema({
title: String,
A schema takes a
body: String,
description object
date: Date,
which specifies its keys
hidden: Boolean,
and their types meta: {
votes: Number,
Types are mostly favs: Number
normal JS }
});
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81. Schema Types
String
Number
Date
Buffer
Boolean
Mixed
ObjectId
Array
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82. Nested Objects
var PersonSchema = new Schema({
Creating nested objects name: {
first: String,
is easy
last: String
}
Just assign an object as });
the value
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83. Array Fields
var PersonSchema = new Schema({
Array fields are easy name: {
first: String,
last: String
Just write the type as a },
single array element hobbies: [String]
});
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84. Schema Use Case
Let’s start writing a
photo taking app var PhotoSchema = new Schema({
username: String,
Each photo is saved photo: String,
in the DB as a Data uploaded_at: Date
URL });
var Photo = mongoose.model(
Along with the
'Photo', PhotoSchema);
photo we’ll save the
username
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85. Creating New Objects
Create a new object
by instantiating the var mypic = new Photo({
username: 'ynon',
model photo: 'foo',
uploaded_at: new Date()
Pass the values to });
the ctor
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86. Creating New Objects
After the object is
ready, simply save it
mypic.save();
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87. What Schema Can Do For You
Add validations on var PhotoSchema = new Schema({
the fields username:
{ type: String, required: true },
Stock validators: photo:
{ type: String, required: true },
required, min, max
uploaded_at: Date
Can also create });
custom validators
Validation happens
on save
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88. What Schema Can Do For You
Provide default var PhotoSchema = new Schema({
values for fields username:
{ type: String, required: true },
Can use a photo:
function as { type: String, required: true },
default for uploaded_at:
{ type: Date, default: Date.now }
delayed
});
evaluation
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89. What Schema Can Do For You
Add methods to your documents
var EvilZombieSchema = new Schema({
name: String,
brainz: { type: Number, default: 0 }
});
EvilZombieSchema.methods.eat_brain = function() {
this.brainz += 1;
};
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90. Custom Validators
It’s possible to use your own validation code
var toySchema = new Schema({
color: String,
name: String
});
toySchema.path('color').validate(function(value) {
return ( this.color.length % 3 === 0 );
});
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91. Schema Create Indices
A schema can have some fields marked as “index”. The
collection will be indexed by them automatically
var PhotoSchema = new Schema({
username: { type: String, required: true, index: true },
photo: { type: String, required: true },
uploaded_at: { type: Date, default: Date.now }
});
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92. Schemas Create Accessors
A virtual field is not saved in the DB, but calculated from
existing fields. “full-name” is an example.
personSchema.virtual('name.full').get(function () {
return this.name.first + ' ' + this.name.last;
});
personSchema.virtual('name.full').set(function (name) {
var split = name.split(' ');
this.name.first = split[0];
this.name.last = split[1];
});
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94. Querying Data
Use Model#find / Model#findOne to query data
// executes immediately, passing results to callback
MyModel.find({ name: 'john', age: { $gte: 18 }},
function (err, docs) {
// do something with data
// or handle err
});
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95. Querying Data
You can also chain queries by not passing a callback
Pass the callback at the end using exec
var p = Photo.find({username: 'ynon'}).
skip(10).
limit(5).
exec(function(err, docs) {
console.dir( docs );
});
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97. Counting Matches
Use count to discover how many matching documents
are in the DB
Adventure.count({ type: 'jungle' }, function (err, count) {
if (err) ..
console.log('there are %d jungle adventures', count);
});
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98. Lab
Create a Schema called “Album”
Add fields: artist, year, tracks
Create a model and a document
Add validator for year
Save it in the DB
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99. Lab
Create 5 albums from years 2008, 2009, 2010, 2011,
2012
Query the 3 newest albums
Print the artist name and the number of tracks
Print the artist who has the most albums
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101. Start With Relationships
Execute the following to create an initial relationship
https://gist.github.com/4657446
Watch the data in the DB:
Album.artist = ObjectId("5106b6e6fde8310000000001")
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102. Use Query#populate
query#populate sends another query for the related
object
Album.findOne().exec(function(err, doc) {
// prints undefined
console.log( doc.artist.name );
});
Album.findOne().populate('artist').exec(function(err, doc) {
// prints Pink Floyd
console.log( doc.artist.name );
});
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103. Use Query#populate
Full method signature:
Query#populate( path, [fields], [model], [cond],
[options] )
cond is a query condition object ( i.e.
{ age: { $gte: 21 }}
options is a query options object ( i.e.
{ limit: 5 }
Helps when populating arrays
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104. Mongoose Plugins
A plugin connects to
the Schema and
extends it in a way
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105. Mongoose Plugins
A mongoose plugin is a simple function which takes
schema and options
Demo: lastModifiedPlugin
https://gist.github.com/4657579
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106. Mongoose Plugins
find or create plugin:
https://github.com/drudge/mongoose-findorcreate
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107. Mongoose Plugins
Hashed password field plugin:
https://gist.github.com/4658951
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108. Mongoose Plugins
Mongoose troops is a collection of useful mongoose
plugins:
https://github.com/tblobaum/mongoose-troop
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109. Thank You
Photos from: http://123rf.com
Slides available at: http://ynonperek.com
Thursday, January 31, 13