mongodb-cheatsheet.md

Working with MongoDB - A Cheatsheet

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Getting into the MongoDB SHELL

1. Fire up MongoDB (or check that it's running)

MacOS: brew services status mongodb/brew/mongodb-community to check status > OR brew services restart mongodb/brew/mongodb-communit to start/restart

2. Get into the MongoDB Shell: mongo <database-name> ( is optional)

$ mongo mongo-crud
MongoDB shell version v4.2.0
connecting to: mongodb://127.0.0.1:27017/mongo-crud?compressors=disabled&gssapiServiceName=mongodb

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MongoDB Shell Commands

• Display current database: db
• See all databases: show databases OR show dbs
• Switch databases: use <database-name>
• See all the collections in a database: show collections

Query Commands:

• Find all documents in a collection: db.collectionName.find()

  • If my collection name is people: db.people.find()
  • Pretty print: db.people.find().pretty()

• Find all item(s) that match a certain field/value pair in a collection: db.collectionName.find({ field: 'search/desired value' })

• Find the first match for a query in a collection: db.collectionName.findOne({ field: 'wanted value' })

  • Use /partial value/ instead of 'wanted value' to find all values containing the partial value eg. db.collectionName.find({ family_name: /Rod/ }) returns 'Rodriguez' and 'Rodgers'

• Find the number of matches of a given query: db.collectionName.find({ field: 'wanted value' }).count()

• Sort query: db.collectionName.find(<query>).sort({ field: -1 }) (-1 is descending, 1 is ascending)

• Limit query: db.collectionName.find(<query>).limit(3) will gave back only 3 or fewer matches

• *DANGER: * Drop the whole database: db.dropDatabase()

• *DANGER: * Drop the whole collection: db.collectionName.drop()

• Delete ONE item from a collection: db.collection.deleteOne(<query>) OR db.collectionName.remove({<query>, true})

• Delete ALL items from a collection: db.collectionName.deleteMany({}) OR db.collectionName.remove({})

• Delete ALL MATCHES of a query from a collection: db.collectionName.deleteMany(<query>) OR db.collectionName.remove(<query>)

Update Documents:

• To add/update/set fields: db.collectionName.update(<query>, { set: <update-object> }, <options>)
• To remove fields: db.collectionName.update(<query>, { $unset: <field-match-query> }, options)
  • Pass {multi: true } as <options> to update multiple matches
• db.collectionName.updateMany(<query>, { $set: <update-object> }, <options>)
• db.collectionName.updateOne(<query>, { $set: <update-object> }, <options>)
• db.collectionName.replaceOne(<query>, { $set: <update-object> }, <options>)

Insert Documents:

• To insert one: db.collectionName.insertOne(<document-object>)
• To insert many: db.collectionName.insertMany([ <doc-obj>, <doc-obj>, <doc-obj> ])
• To insert: db.collectionName.insert(<doc-obj>) OR db.collectionName.insert([ <doc-obj>, <doc-obj>, <doc-obj> ])