To use the mongo shell in terminal

• type
• mongo
• prompt should change from bash $ to >

Show DBs

• show dbs

Show which db is in use

• db

Switch to a database (will also create the database, if it does not exist)

• use databseName

Create a collection

• db.createCollection(‘collectionName’)

Show collections in database

• show collections

Show data or show documents

• db.collectionName.find()
• Make it pretty `db.collectionName.find().pretty()

Find something specific

• From the docs db.collectionName.find ( <field> : <value> )
  • How you would actually type it out:
  • db.collectionName.find( { school: “General Assembly”})
• More from the docs : https://docs.mongodb.com/manual/reference/method/db.collection.find/

Find one

• db.collectionName.findOne()
• find one and show only the name and school fields
  • db.collectionName.findOne({}, { name: 1 , school :1 })
• find one and exclude the id field
  • db.collectionName.findOne( {} , { _id : 0 })

• db.collectionName.remove ({state : ’NY’})

• db.collectionName.drop()

• use dbToBeDropped
• db.dropDatabase()

⌃ C or exit or quit()

⌃ C

Gracefully exit out of terminal (still need to close window after executing, but will delete expired sessions) exit

Problem exiting mongod?

In terminal

1. ps -A | grep mongod
2. find the line that just mentions mongod, but not grep
3. take note of the number on the left
4. type kill 1774 or whatever that number is. Try mongod again.
5. If that doesn't work, go to /data/db and rm mongod.lock. Try mongod again.

https://docs.mongodb.com/manual/crud/

See Options Table below, to understand the parameters in each method

From the Mongo Documentation

What these parameters mean in the methods listed above

When using update, you must use at least one of these operators, or else your document will be destroyed

Mongo docs for update (fields, arrays and modifiers)

• A few common update operators:
• $inc : increment the value
• $rename : renames a field
• $set : set the value of a field
• $unset : remove the specified field from a document

• Note : failing to use an operator, will cause the document to be overwritten and 'destroyed'

• Note : Modifying arrays for updates use their own operators like $pull, $pop, $push (scroll down in the above doc to see)

Example:

db.students.findOneAndUpdate({ name: 'Karolin'}, {$set:{graduated: true}})

When searching for specific docs, these selectors can help you find what you want

Mongo docs for query selectors

• You can use query selectors like
• $eq : matches values that are equal to a specified value
• $ne : matches all values that are not equal to the specified value
• $gt : matches values that are greater than a specified value
• $gte : matches values that are greater than or equal to a specified value
• $in : matches any of the values specified in an array
• $nin : matches none of the values specified in an array
• $lt : matches values that are less than a specified value
• $lte : matches values that are less than or equal to a specified value
• You can use logical operators like $and, $not, $nor and $or
• You can select if a field exists using $exists

Example:

db.students.find({state:{$ne:'NY'}})

This will find all the students who do NOT live in NY state.

var schema = new Schema({
  name:    String,
  binary:  Buffer,
  living:  Boolean,
  updated: { type: Date, default: Date.now },
  age:     { type: Number, min: 18, max: 65 },
  mixed:   Schema.Types.Mixed,
  _someId: Schema.Types.ObjectId,
  decimal: Schema.Types.Decimal128,
  array: [],
  ofString: [String],
  ofNumber: [Number],
  ofDates: [Date],
  ofBuffer: [Buffer],
  ofBoolean: [Boolean],
  ofMixed: [Schema.Types.Mixed],
  ofObjectId: [Schema.Types.ObjectId],
  ofArrays: [[]],
  ofArrayOfNumbers: [[Number]],
  nested: {
    stuff: { type: String, lowercase: true, trim: true }
  },
  map: Map,
  mapOfString: {
    type: Map,
    of: String
  }
})

// example use

var Thing = mongoose.model('Thing', schema);

var m = new Thing;
m.name = 'Statue of Liberty';
m.age = 125;
m.updated = new Date;
m.binary = new Buffer(0);
m.living = false;
m.mixed = { any: { thing: 'i want' } };
m.markModified('mixed');
m._someId = new mongoose.Types.ObjectId;
m.array.push(1);
m.ofString.push("strings!");
m.ofNumber.unshift(1,2,3,4);
m.ofDates.addToSet(new Date);
m.ofBuffer.pop();
m.ofMixed = [1, [], 'three', { four: 5 }];
m.nested.stuff = 'good';
m.map = new Map([['key', 'value']]);
m.save(callback);