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[https://htcvtc59.github.io/mongodbNote]

10917 MongoDB for Node.js Developers Using Shell to access Mongo in Terminal
mongod 'database' : 'mongodb://localhost/Insta'

Using Shell via Terminal show dbs | use | show collections

Create, Insert, Update, Find, Remove

db.createCollection('') db..insert({ title: 'car 1', make: 'honda', year: '2010' }); db.categories.update({name:'Technology'}, {$set: {description: 'learn more about tech stuff'}}) db.users.update({email: "[email protected]"}, { $set: {"role" : "admin"}}, {$upsert: true}); db.users.update({email: '[email protected]'}, {$set:{email:'[email protected]'}}) db.things.find() //connector to interact with database //Using my DB find all the things db.things.remove ({}) db.things.insert({ "a" : 1, "b" : 2, "c" : 3 }) db.things.find({ "a" : 1 }) //finds documents with only specified field db.things.find().pretty() //prints a more readable data set for (var i = 0; i<10; i++) { db.things.insert({ "x" : i }) } //goes through 10 docs inserts 'x' db.test_users.remove( {"_id": ObjectId("563e24b14dc3382c17c7d006")}); - remove by ID

Comparison Query Operators $gt greater than $gte greater than or equal to $in exists in $lt less than $lte less than or equal to $ne not equal to $nin does not exist

What is MongoDB? Non-relational, Stores in JSON documents, Horizontally Scaled Schemaless -> 2 docs don't need to have the same schema Brings together: Scalability & Peformance + Functionality Document is instance of the model

Does Not Support: Joins and Transactions (across multiple documents)

The Process Client makes a request that goes to server. Node.JS processes and returns something. If your app neds to store persistent data then use Mongo. App makes a request and Mongo responds when completed.

Mongo Shell (administration interface) Like mongo & node it is a C++ controlled using V8. You can open a terminal and make requests to mongo which will get a reponse. Useful for doing things like: asking questions about configuration, seeing what is stored or debugging app.

Driver This is what is used to communicate between Node and Mongo. Use API to move/insert doc

Intro to JSON Basic Structure -- {"a" : 1} Value Types -- string, bool, number Basic Nesting -- arrays, nested objects Deep Nesting -- combines arrays with objects

var course = db.deepnested.findOne() course //access the JSON object course.students course.students[0].name //call the element course['students'][0].name course.students[0].name = "Sue"

Asynchronous vs Synchronous (Mongo is Sync, and Node is Async) Names for handling operations that don't require active work on running thread When using Asynchronous your able to run calls to the app parallel

Node.js function(err, doc) - - common convention for the callback -> take err as 1st param, value as 2nd

node app.js // 'Called findOne!' { name: 'MongoDB' } npm install // installs the modules located in package.json (node_modules directory) npm remove X | npm insall [email protected]

Creating/Accessing files make the folder and add/edit source code as .JS file. Navigate via cd + folder.

node app.js //or location of the file 'Hello World' app.js file creates a server and tells it what to do when receiving request

Using Commands cd (+ folder opens directory) | ls (shows files in folder) | cls (clears prompt) mkdir (+ name creates folder) | ctrl+C (if cmd froze) |

Express 2 ways Express can get data from client side of an application: use GET and SET

MongoDB is Schemaless -- Don't need to have same keys in same document, provides flexibility to add/subtract/change

JSON Revisited Arrays - list of things [] Dictionaries - associated maps {} {name: "value", city: "value", interests: [1, 2, 3]

Modeling our Blog in Mongo posts: {title:"free classes", body:"...", author:"me", date:"8/13", comments:[{name:"Joe", email: "me@me", comment: "hi"{....}], {tags: ["cycling", "education", "startups"]} authors: {_id: "myId", password:"234"}

Week 2 CRUD - create = Insert, read = Find, update = Update, delete = Delete -- Operation exists as methods/functions

Connecting to the Mongo Shell

cd \Program Files\MongoDb 2.6 Standard\bin -- Use ^ arrow to reload previous statement. Use Ctrl + A go to beginning, Home or End

Inserting Docs doc = {'name' : 'smith', 'age' : '30', 'profession' : 'hacker'} //use this in place of doc to direct insert

db.people.insert( doc ) //interprets as name of collection inside current database db.people.find() //see what's there -- You get back a '_id' : ObjectId -- which is the primary field db.people.findOne({'name' : 'jones' }) //finds document with named parameters db.people.findOne({'name' : true, '_id' : false}) //specifying certain fields to retrieve

The find field

db.scores.find({ student: 19 , type : "essay" }, {"score" : true , "_id" : false });

Query Operators

db.scores.find({score : { $gt : 95 }}); //score should be greater then 95 db.scores.find({score : { $gte : 95, $lte : 98 } , type : "essay"}); //between 95-98 w/ type essay db.people.find({ name : { $lt : "D" }});

Using $exists, $type + true or false - Use to return a list of users meet parameters

db.people.find ({ profession : { $exists : false }}); //say true or false db.people.find ({ name : { $type : 2 }}); //type for 'string' is 2 – search bson types

Regular Expressions - Allows you to do complicated string matching inside of fields

db.people.find({ name : { $regex : "a"}}); //find all people with an 'a' in their name db.people.find({ name : { $regex : "$e"}}); //ends with the letter 'e' db.people.find({ name : { $regex : "^A" }}); // ^ must begin with whatever follows

Using $or - Prefix operator (takes an array as an operand) Matches any that meet criteria

db.people.find({$or : [{ name : { $regex : 'e$' }}, {age : { $exists : true }}]});

Using $and

db.people.find({$and : [{name : { $gt : 'C' }}, {name : { $regex : "a"}}]});

Querying inside Arrays

db.accounts.insert({name : "howard", favorites : ["pretzels", "beer"]}); db.accounts.insert({ favorites : 'pretzels, name : {$gt : 'H'}});

Using $in and $all - Takes in an array //Returns documents with the Field queried

db.accounts.find({favorites : {$all : ['pretzels', 'beer']}}); //matches All elements in the field db.accounts.find({name : {$in : ['Howard', 'John"]}}); //returns docs with at least 1 element

-- If not including the $ operator the order must be the same as in the DB

Dot Notation

db.users.find({"email.work" : "[email protected]"}); db.catalog.find( { price : { $gt : 10000 } , "reviews.rating" : { $gte : 5 } } );

Querying Cursors

cur.next() //steps through to the next document Methods: hasNext(), next(), limit(), sort(), skip() cur.sort({name : -1 }); null; //shows names from Z-A then #'s cur.sort({name : -1}).limit(3); null; cur.sort({name : -1}).limit(3).skip(2); null; db.scores.find({type : 'exam"}).sort({score : -1}).skip(50).limit(20)

Counting - Counting up all documents that match a criteria

db.scores.count({ type : 'exam'}); db.scores.count({type : 'essay', score : {$gt : 90}});

Updating Documents -- Methods on a collection, replaces 1st with 2nd param

db.people.update({ name : 'Smith'}, {name : 'Thompson' , salary : 50000}); //replaces smith

Using $set Command -- Find all instances with Alice and set her age to 30 ({ name : "Alice" }, { $set : { age : 30 }})

Use $inc will increment by 1 ({ name : "Alice" }, { $inc : { age : 1 }}) //makes the age 31 ** You can $inc by any number (20)

Using the $unset Command //removes field

db.people.update ({name : "Jones" }, {$unset : {profession : 1}})

Using $push, $pop, $pull, $pushAll, $pullAll, $addToSet

db.arrays.update ({ _id : 0}, {$push : {a : 6}}) // will add 6 to the end of array db.arrays.update ({ _id : 0}, {$pop : {a : 1}}) // will remove last element in array db.arrays.update ({ _id : 0}, {$pop : {a : -1}}) // will remove first element in array db.arrays.update ({ _id : 0}, {$pushAll : {a : [7, 8, 9]}}) //adds 7, 8, 9 to end db.arrays.update ({ _id : 0}, {$pull : {a : 5}}) //removes value no matter location db.arrays.update ({ _id : 0}, {$pullAll : {a : [7, 8, 9]}}) //removes 7, 8, 9 from the array db.arrays.update ({ _id : 0}, {$addToSet : {a : 5}}) // will add 5 to the array if doesn't exist

Using $upsert //updates existing record or adds a new one

db.people.update({ name : 'George' }, {$set : {age : 40}}, {upsert : true})

Multi-Update //if you don't supply {multi} then only affects 1 document

db.people.update({}, {$set : {title : 'Dr'}}, {multi : true}) //open paren updates all docs w/ title

Removing from the Database

db.remove({ name : 'Alice'}) db.people.remove ({}) //empty removes all docs from collection db.people.drop() //faster way of removing All collections

Importing Files

mongoimport -d course -c grades grades.json //start mongod, import file to node cmd mongo //connect to mong use course //switched to db course collection db.grades.find() //prints out collection items

Examples: findOne() - returns the first document that meets requirements find (toArray) - returns all students with 100 using the toArray method find_cursors (each) - finds students with 100 and prints message find_lt_gt - find docs with grades between x and y

Importing JSON from other sites -- request = require('request'); -- request('http://reddit.json', function(error, response, body) var obj = JSON.parse(body); var stories = obj.data.children.map(function (story) { return story.data; }); db.collection('reddit').insert(stories, function (err, data) {

Using $regex

db.reddit.find({ 'title' : { '$regex' : 'NSA' }}, {'title' : 1, '_id' : 0}); //finds all docs with NSA in title Sort, Limit, Skip //Order doesn't matter cursor.sort([['grade', 1], ['student', -1]]); var options = { 'skip' : 1, 'limit' : 4, 'sort' : [['grade', 1], ['student', -1]] }; var cursor = grades.find({}, {}, options); //empty, projector, call var options

Find and Modify // find docs matching query, update and show result var query = { 'name' : 'comments' }; var sort = []; var operator = { '$inc' : { 'counter' : 1 } }; var options = { 'new' : true }; //we want the new doc to be returned db.collection('counters').findAndModify(query, sort, operator, options, function(err, doc) {

Week 3 Rich Documents Pre Join / Embed Data No Constraints Atomic Operations No Declared Schema (similar structure)

Week 4 Indexes -> indexes are collected as top level arrays which can be called in by order when doing query, sort or find.
(name, hair_color, dob) - start with name then optional use hair_color Create an Index

db.students.ensureIndex({student_id:1,class:-1}) //makes student ascending and class descend

Find an Index -- You can only use find() and/or sort() on a db when asking for first index

db.system.indexes.find() db.students.getIndexes() -- Displays the indexes db.students.dropInxex({'student_id':1}) //remove index

Multikey Indexes - an index w/ an array { name: 'Andrew', tags: ['cycling', 'tennis', 'football'], color: 'red' locations: ['NY', 'CA']} You can create a compound index on tags/color. But can't on 2 indexes that contain arrays

Adding a Unique Index

db.students.ensureIndex({student_id:1, class_id:1}, {unique:true})

Dropping Duplicate Index

db.things.ensureIndex({thing: 1}, {unique: true, dropDups: true})

Explain -- provides a break down of the data returned related to query

db.foo.find({c:1}).explain()

Geospatial Indexes - 2d Index -- 'location' : [x, y] -- ensureIndex({"location" : '2d', type : 1 }) -- db.stores.ensureIndex (creates index)

find({location:{$near:[x, y]}}).limit(20) -- returns in increasing distance

Geospatial Spherical - 2dsphere Uses geoJSON (Point, Polygon) longitude, latitude

db.places.ensureIndex({'location': '2dsphere'}) "location" : { "type" : "Point", "coordinates" : [-122.169129, 37.4434854] }, "type" : "Retail" } db.places.find({loc:{$near:{$geometry:{type:"point",coordinates:[122,33]},$maxDistance:2000}}}).pretty()

Text Searches

db.sentences.find({ $text: {$search:'dog' }}) //implies a logical OR operator

Find 'best' match first

db.sentences.find({$text:{$search:'dog tree obsidian'}}, {score:{$meta: 'textScore'}}).sort({score:{$meta:'textScore'}})

Simple Aggregation

db.products.aggregate([{$group:{"_id":"$category", "num_products":{"$sum":1}}}])

Aggregation Pipeline $project - reshape - 1 : 1 $match - filter - n : 1 $group - aggregate - n : 1 $sort - sort - 1 : 1 $skip - skips - n : 1 $limit - limits - n : 1 $unwind - normalize - 1 : n (expands items in array) $out - output - 1 : 1