| Mongo data type | Stores | Example |
|---|---|---|
| null | null value & non existent field | {"x": null} |
| boolean | true, false | {"processed": true} |
| 32 Bit Integer | JavaScript Number | |
| 64 Bit Integer | JavaScript Number | |
| 64 Bit Float | JavaScript Number | |
| date | ISO Date | Use new Date() ISODate("2017-07-24T10:21:33.430Z"), |
| Arrays | {"x": [1,2,3]} | |
| objects | {"x": {y: "z"}} | |
| code | JavaScript code | {"x": function() {}} |
4 Byte Timestamp
3 Bytes Auto Incr
3 Bytes Machine ID
2 Bytes Process ID
> help
db.help() help on db methods
db.mycoll.help() help on collection methods
sh.help() sharding helpers
rs.help() replica set helpers
help admin administrative help
help connect connecting to a db help
help keys key shortcuts
help misc misc things to know
help mr mapreduce
show dbs show database names
show collections show collections in current database
show users show users in current database
show profile show most recent system.profile entries with time >= 1ms
show logs show the accessible logger names
show log [name] prints out the last segment of log in memory, 'global' is default
use <db_name> set current database
db.foo.find() list objects in collection foo
db.foo.find( { a : 1 } ) list objects in foo where a == 1
it result of the last line evaluated; use to further iterate
DBQuery.shellBatchSize = x set default number of items to display on shell
exit quit the mongo shell// insert_records.js
var i = 10000;
while (--i > 0) {
db.logs.insert({createdAt: new Date(), value: Math.random() * i})
}
// execute insert
mongo <database> <jsfile> // Create single document
db.person.insert({firstName: 'John', lastName: 'Doe', verified: false})
// Bulk insert documents
db.person.insert([
{ firstName: 'Jack', lastName: 'Doe', verified: false },
{ firstName: 'Jill', lastName: 'Doe', verified: false }
])// Remove all documents
db.persons.remove()
var persons = [
{firstName: 'John', lastName: 'Doe', isVerified: false },
{firstName: 'Jill', lastName: 'Doe', isVerified: false },
{firstName: 'John', lastName: 'Doe', isVerified: true },
{firstName: 'Jill', lastName: 'Doe', isVerified: true }
]
db.persons.insert(persons)
// remove using a query
db.persons.remove({isVerified: true })
// Drop the collection
db.persons.drop()// Update a document
db.persons.update({firstName: 'John'}, {age: 27})
db.persons.update({_id:ObjectId(<your _id here>)}, {age: 27})
// update parts of a document
db.persons.update({firstName: 'John', lastName: 'Doe'}, {$set: {age: 27}})
db.persons.update({firstName: 'John', lastName: 'Doe'}, {$unset: {age: 1}})
// Update subdocuments
db.persons.update({firstName: 'John', lastName: 'Doe'}, {$set: {friends.0.name: 'Mira'}})
// What happens ?
db.persons.update({}, {n: 33})
db.persons.update({}, {n: 33}, {multi: true})
Modifiers
// $inc
db.persons.update({}, {$inc: {age: 1}}, {multi: true})
// Array Modifiers
// $push
db.persons.update({firstName: 'John', lastName: 'Doe'}, {$push: {friends: "Jill Doe"}})
// $ne -- Dont push if value is present
db.persons.update({firstName: 'John', lastName: 'Doe', friends: {$ne: "Jill Doe"}}, {$push: {friends: "Jill Doe"}})
// $addToSet prevent duplicates
db.persons.update({firstName: 'John', lastName: 'Doe'}, {$addToSet: {friends: "Jill Doe"}})
// Multiple values
db.persons.update({firstName: 'John', lastName: 'Doe'}, {$addToSet: {friends: {$each: ["Jill Doe", "Jack Doe"]}}})// Update a document
// $pop -- Positional
db.persons.update({firstName: 'John', lastName: 'Doe'}, {$pop: {friends: 1}})
db.persons.update({firstName: 'John', lastName: 'Doe'}, {$pop: {friends: -1}})
// $pull -- remove by criteria
db.persons.update({firstName: 'John', lastName: 'Doe'}, {$pull: {friends: 'Jill Doe'}})
// Upsert
db.persons.update({firstName: 'Jeff', lastName: 'Doe'}, {firstName: 'Jeff', lastName: 'Doe', age: 32}, {upsert: true})
Command line tools
mongoexport --db myapp --collection persons --out persons_export.json
mongoimport --db myapp --collection persons --file persons.json
mongoimport --db myapp --drop --collection persons --file persons.json
// Find All
db.persons.find({})
// Find using queries
db.persons.find({age: 27})
db.persons.find({age: 27, firstName: 'Joe'})
// Projections
db.persons.find({}, {firstName: 1, age: 1})
// Conditions
// $lt, $lte, $gt, $gte, $ne
db.persons.find({age: {$gte: 21, $lte: 30})
db.persons.find({age: {$ne: 0})
// OR Queries
// $in, $nin
db.persons.find({lastName: {$in: ['Doe', 'Miller']})
db.persons.find({lastName: {$in: ['Miller']})
// $or
// Or with multiple keys
db.persons.find({$or: [{lastName: 'Doe'}, {age: {$gte: 10}}]})
// $not
db.persons.find({lastName: {$not: {$ne: 'Doe'}}})// Find nulls
db.persons.find({z: null})
db.persons.find({z: {$eq: null, $exists: true}})
// Regular Expression
db.persons.find({firstName: /john/i})
// Arrays
db.persons.find({friends: 'Jill'})
// Arrays more than one match
db.persons.find({friends: {$all: ['Jill', 'Jim']})
// Size
db.persons.find({friends: {$size: 3}})
// Slice
db.persons.find({friends: {$slice: 1}})
db.persons.find({friends: {$slice: -1}})
// Querying Embedded documents
db.persons.find({'address.postCode': 600020})
// $where queries
db.persons.find({$where: function () { return this.firstName === 'Jack'}})
db.persons.find({$where: "this.firstName === 'Jack'")// Limits, skips and sorts
db.persons.find({}).limit(10)
db.persons.find({}).skip(10)
// Pagination
db.persons.find({}).limit(10).skip(10)
// Sorting
db.persons.find({}).sort({age: 1})const fs = require('fs');
const Chance = require('chance');
const chance = new Chance();
function generateRandomPerson () {
const gender = chance.gender();
const first = chance.first({gender: gender.toLowerCase()});
const last = chance.last();
return {
firstname: first,
lastname: last,
email: first + '.' + last + '@example.com',
dob: chance.date({year: chance.pickone([1981, 1983, 1985])})
};
}
var stream = fs.createWriteStream("persons.json");
stream.once('open', function(fd){
// stream.write('[');
for(var i=0; i < 5000; i++) {
// i === 0 ? stream.write('') : stream.write(',');
stream.write(JSON.stringify(generateRandomPerson()));
stream.write('\n');
}
// stream.write(']');
stream.end();
});// mongoimport
mongoimport --db myapp --drop --collection persons --file persons.json
db.persons.group(
{
key: { firstname: 1 },
reduce: function( curr, result ) {
result.total += 1;
},
initial: { total : 0 }
}
)
db.persons.group({
keyf: function(doc) {
return { year: doc.dob.getFullYear() + '_' + doc.firstname };
},
cond: { dob: { $gt: new Date('1980/01/01') } },
reduce: function( curr, result ) {
result.total += 1;
result.count++;
},
initial: { total : 0, count: 0 }
})
db.persons.aggregate([
{$match: { dob: {$gte: new Date('1985/01/01')}}},
{$project: { year: {$year: "$dob"}, firstname: "$firstname"}},
{$group: {_id: {"year": "$year", firstname: "$firstname"}, count: {$sum: 1}}}
])var mapper = function () {
emit(this.lastname, 1)
}
var reducer = function (name, instances) {
return Array.sum(instances)
}
db.persons.mapReduce(
mapper,
reducer,
{
out: "mr_bylastname"
}
)