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diff --git a/mongodb.html.markdown b/mongodb.html.markdown new file mode 100644 index 00000000..959b57d0 --- /dev/null +++ b/mongodb.html.markdown @@ -0,0 +1,405 @@ +--- +language: MongoDB +filename: mongo.js +contributors: + - ["Raj Piskala", "https://www.rajpiskala.ml/"] +--- + +MongoDB is a NoSQL document database for high volume data storage. + +MongoDB uses collections and documents for its storage. Each document consists +of key-value pairs using JSON-like syntax, similar to a dictionary or JavaScript +object. + +Likewise, as MongoDB is a NoSQL database, it uses its own query language, Mongo +Query Language (MQL) which uses JSON for querying. + +## Getting Started + +### Installation + +MongoDB can either be installed locally following the instructions +[here](https://docs.mongodb.com/manual/installation/) or you can create a +remotely-hosted free 512 MB cluster +[here](https://www.mongodb.com/cloud/atlas/register). Links to videos with +instructions on setup are at the bottom. + +This tutorial assumes that you have the MongoDB Shell from +[here](https://www.mongodb.com/try/download/shell). You can also download the +graphical tool, MongoDB Compass, down below from the same link. + +### Components + +After installing MongoDB, you will notice there are multiple command line tools. +The three most important of which are: + +- `mongod` - The database server which is responsible for managing data and + handling queries +- `mongos` - The sharding router, which is needed if data will be distributed + across multiple machines +- `mongo` - The database shell (using JavaScript) through which we can configure + our database + +Usually we start the `mongod` process and then use a separate terminal with +`mongo` to access and modify our collections. + +### JSON & BSON + +While queries in MongoDB are made using a JSON-like\* format, MongoDB stores its +documents internally in the Binary JSON (BSON format). BSON is not human +readable like JSON as it's a binary encoding. However, this allows for end users +to have access to more types than regular JSON, such as an integer or float +type. Many other types, such as regular expressions, dates, or raw binary are +supported too. + +[Here](https://docs.mongodb.com/manual/reference/bson-types/) is the full list +of all types that are supported. + +- We refer JSON-like to mean JSON but with these extended types. For example, + you can make queries directly with a regular expression or timestamp in + MongoDB and you can receive data that has those types too. + +```js +///////////////////////////////////////////////////////// +/////////////////// 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.find(<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({ $gt: { age: 25 }}) +db.engineers.find({ $gte: { age: 25 }}) + +// Find all less than or less than equal to some condition +db.engineers.find({ $lte: { age: 25 }}) +db.engineers.find({ $lte: { age: 25 }}) + +// Find all equal or not equal to +// Note: the $eq operator is added implicitly in most queries +db.engineers.find({ $eq: { age: 25 }}) +db.engineers.find({ $ne: { age: 25 }}) + +// Find all that match any element in the array +db.engineers.find({ age: ${ in: [ 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 +``` + +## Further Reading + +### Setup Videos + +- [Install MongoDB - Windows 10](https://www.youtube.com/watch?v=85A6m1soKww) +- [Install MongoDB - Mac](https://www.youtube.com/watch?v=DX15WbKidXY) +- [Install MongoDB - Linux + (Ubuntu)](https://www.youtube.com/watch?v=wD_2pojFWoE) + +### Input Validation + +From the examples above, if input validation or structure is a concern, I would +take a look at the following ORMs: + +- [Mongoose (Node.js)](https://mongoosejs.com/docs/) - Input validation through + schemas that support types, required values, minimum and maximum values. +- [MongoEngine (Python)](http://mongoengine.org/) - Similar to Mongoose, but I + found it somewhat limited in my experience +- [MongoKit (Python)](https://github.com/namlook/mongokit) - Another great + alternative to MongoEngine that I find easier to use than MongoEngine + +For statically strongly typed languages (e.g. Java, C++, Rust), input validation +usually doesn't require a library as they define types and structure at compile +time. + +### Resources + +If you have the time to spare, I would strongly recommend the courses on +[MongoDB University](https://university.mongodb.com/). They're by MongoDB +themselves and go into much more detail while still being concise. They're a mix +of videos and quiz questions and this was how I gained my knowledge of MongoDB. + +I would recommend the following video series for learning MongoDB: + +- [MongoDB Crash Course - Traversy + Media](https://www.youtube.com/watch?v=-56x56UppqQ) +- [MongoDB Tutorial for Beginners - + Amigoscode](https://www.youtube.com/watch?v=Www6cTUymCY) + +Language-specific ones that I used before: + +- [Build A REST API With Node.js, Express, & MongoDB - Web Dev + Simplified](https://www.youtube.com/watch?v=fgTGADljAeg) +- [MongoDB with Python Crash Course - Tutorial for Beginners - + FreeCodeCamp](https://www.youtube.com/watch?v=E-1xI85Zog8) +- [How to Use MongoDB with Java - Random + Coder](https://www.youtube.com/watch?v=reYPUvu2Giw) +- [An Introduction to Using MongoDB with Rust - + MongoDB](https://www.youtube.com/watch?v=qFlftfLGwPM) + +Most of the information above was cross-referenced with the [MongoDB +docs](https://www.mongodb.com/). Here are the docs for each section: + +- [MongoDB Types](https://docs.mongodb.com/manual/reference/bson-types/) - List + of all types that MongoDB supports natively +- [MongoDB Operators](https://docs.mongodb.com/manual/reference/operator/) - + List of operators MongoDB supports natively +- [MongoDB CRUD](https://docs.mongodb.com/manual/reference/command/nav-crud/) - + Commands for create, read, update, delete + +If you've been enjoying MongoDB so far and want to explore intermediate +features, I would look at +[aggregation](https://docs.mongodb.com/manual/reference/command/nav-aggregation/), +[indexing](https://docs.mongodb.com/manual/indexes/), and +[sharding](https://docs.mongodb.com/manual/sharding/). + +- Aggregation - useful for creating advanced queries to be executed by the + database +- Idexing allows for caching, which allows for much faster execution of queries +- Sharding allows for horizontal data scaling and distribution between multiple + machines. |