Learn X in Y minutes

/////////////////////////////////////////////////////////
/////////////////// Getting Started /////////////////////
/////////////////////////////////////////////////////////

// Start up the mongo database server
// NOTE - You will need to do this in a separate terminal as the process will 
// take over the terminal. You may want to use the --fork option
mongod // --fork

// Connecting to a remote Mongo server
// mongo "mongodb+srv://host.ip.address/admin" --username your-username

// Mongoshell has a proper JavaScript interpreter built in
3 + 2 // 5

// Show available databases
// MongoDB comes with the following databases built-in: admin, config, local
show dbs

// Switch to a new database (pre-existing or about to exist)
// NOTE: There is no "create" command for a database in MongoDB. 
// The database is created upon data being inserted into a collection
use employees

// Create a new collection
// NOTE: Inserting a document will implicitly create a collection anyways,
// so this is not required
db.createCollection('engineers')
db.createCollection('doctors')

// See what collections exist under employees
show collections

/////////////////////////////////////////////////////////
// Basic Create/Read/Update/Delete (CRUD) Operations: ///
/////////////////////////////////////////////////////////

/////////////// Insert (Create) /////////////////////////

// Insert one employee into the database
// Each insertion returns acknowledged true or false
// Every document has a unique _id value assigned to it automatically
db.engineers.insertOne({ name: "Jane Doe", age: 21, gender: 'Female' })

// Insert a list of employees into the `engineers` collection
// Can insert as an array of objects
db.engineers.insert([
  { name: "Foo Bar", age: 25, gender: 'Male' },
  { name: "Baz Qux", age: 27, gender: 'Other' },
])

// MongoDB does not enforce a schema or structure for objects
// Insert an empty object into the `engineers` collection
db.engineers.insertOne({})

// Fields are optional and do not have to match rest of documents
db.engineers.insertOne({ name: "Your Name", gender: "Male" })

// Types can vary and are preserved on insertion
// This can require additional validation in some languages to prevent problems
db.engineers.insert({ name: ['Foo', 'Bar'], age: 3.14, gender: true })

// Objects or arrays can be nested inside a document
db.engineers.insertOne({
  name: "Your Name",
  gender: "Female",
  skilledIn: [
    "MongoDB",
    "NoSQL",
  ],
  "date-of-birth": {
    "date": 1993-07-20T09:44:18.674Z,
    "age": 26
  },
})

// We can override the _id field
// Works fine
db.engineers.insertOne({
  _id: 1,
  name: "An Engineer",
  age: 25,
  gender: "Female",
})

// Be careful, as _id must ALWAYS be unique for the collection otherwise 
// the insertion will fail
// Fails with a WriteError indicating _id is a duplicate value
db.engineers.insertOne({
  _id: 1,
  name: "Another Engineer",
  age: 25,
  gender: "Male",
})

// Works fine as this is a different collection
db.doctors.insertOne({
  _id: 1,
  name: "Some Doctor",
  age: 26,
  gender: "Other",
})

/////////////////// Find (Read) ////////////////////////
// Queries are in the form of db.collectionName.find(<filter>)
// Where <filter> is an object

// Show everything in our database so far, limited to a 
// maximum of 20 documents at a time
// Press i to iterate this cursor to the next 20 documents
db.engineers.find({})

// We can pretty print the result of any find() query
db.engineers.find({}).pretty()

// MongoDB queries take in a JS object and search for documents with matching 
// key-value pairs
// Returns the first document matching query
// NOTE: Order of insertion is not preserved in the database, output can vary
db.engineers.findOne({ name: 'Foo Bar' })

// Returns all documents with the matching key-value properties as a cursor 
// (which can be converted to an array)
db.engineers.find({ age: 25 })

// Type matters when it comes to queries
// Returns nothing as all ages above are integer type
db.engineers.find({ age: '25' })

// find() supports nested objects and arrays just like create()
db.engineers.find({
  name: "Your Name",
  gender: "Female",
  skilledIn: [
    "MongoDB",
    "NoSQL",
  ],
  "date-of-birth": {
    "date": 1993-07-20T09:44:18.674Z,
    "age": 26
  },
})

///////////////////////// Update ////////////////////////
// Queries are in the form of db.collectionName.update(<filter>, <update>)
// NOTE: <update> will always use the $set operator.
// Several operators are covered later on in the tutorial.

// We can update a single object
db.engineers.updateOne({ name: 'Foo Bar' }, { $set: { name: 'John Doe', age: 100 }})

// Or update many objects at the same time
db.engineers.update({ age: 25 }, { $set: { age: 26 }})

// We can use { upsert: true } if we would like it to insert if the document doesn't already exist,
// or to update if it does
// Returns matched, upserted, modified count
db.engineers.update({ name: 'Foo Baz' },
  { $set:
    {
      age: 26,
      gender: 'Other'
    }
  },
  { upsert: true }
)

/////////////////////// Delete /////////////////////////
// Queries are in the form of db.collectionName.delete(<filter>)

// Delete first document matching query, always returns deletedCount
db.engineers.deleteOne({ name: 'Foo Baz' })

// Delete many documents at once
db.engineers.deleteMany({ gender: 'Male' })

// NOTE: There are two methods db.collection.removeOne(<filter>) and 
// db.collection.removeMany(<filter>) that also delete objects but have a
// slightly different return value.
// They are not included here as they have been deprecated in the NodeJS driver.

/////////////////////////////////////////////////////////
//////////////////// Operators //////////////////////////
/////////////////////////////////////////////////////////

// Operators in MongoDB have a $ prefix. For this tutorial, we are only looking 
// at comparison and logical operators, but there are many other types of
// operators

//////////////// Comparison Operators ///////////////////

// Find all greater than or greater than equal to some condition
db.engineers.find({ age: { $gt: 25 }})
db.engineers.find({ age: { $gte: 25 }})

// Find all less than or less than equal to some condition
db.engineers.find({ age: { $lt: 25 }})
db.engineers.find({ age: { $lte: 25 }})

// Find all equal or not equal to
// Note: the $eq operator is added implicitly in most queries
db.engineers.find({ age: { $eq: 25 }})
db.engineers.find({ age: { $ne: 25 }})

// Find all that match any element in the array, or not in the array
db.engineers.find({ age: { $in: [ 20, 23, 24, 25 ]}})
db.engineers.find({ age: { $nin: [ 20, 23, 24, 25 ]}})

//////////////// Logical Operators ///////////////////

// Join two query clauses together
// NOTE: MongoDB does this implicitly for most queries
db.engineers.find({ $and: [
  gender: 'Female',
  age: {
    $gte: 18
  }
]})

// Match either query condition
db.engineers.find({ $or: [
  gender: 'Female',
  age: {
    $gte: 18
  }
]})

// Negates the query
db.engineers.find({ $not: {
  gender: 'Female'
}})

// Must match none of the query conditions
db.engineers.find({ $nor [
  gender: 'Female',
  age: {
    $gte: 18
  }
]})

/////////////////////////////////////////////////////////
//////////////// Database Operations: ///////////////////
/////////////////////////////////////////////////////////

// Delete (drop) the employees database
// THIS WILL DELETE ALL DOCUMENTS IN THE DATABASE!
db.dropDatabase()

// Create a new database with some data
use example
db.test.insertOne({ name: "Testing data, please ignore!", type: "Test" })

// Quit Mongo shell
exit

// Import/export database as BSON:

// Mongodump to export data as BSON for all databases
// Exported data is found in under "MongoDB Database Tools/bin/dump"
// NOTE: If the command is not found, navigate to "MongoDB Database Tools/bin" 
// and use the executable from there mongodump

// Mongorestore to restore data from BSON
mongorestore dump

// Import/export database as JSON:
// Mongoexport to export data as JSON for all databases
mongoexport --collection=example

// Mongoimport to export data as JSON for all databases
mongoimport  --collection=example