Mongodb | And Mongoose Freecodecamp

| SQL | MongoDB | |--------------|---------------| | Database | Database | | Table | Collection | | Row | Document | | Column | Field | 2. Mongoose Setup Install npm install mongoose Connect to MongoDB const mongoose = require('mongoose'); mongoose.connect('mongodb://localhost:27017/myApp', useNewUrlParser: true, useUnifiedTopology: true );

"_id": ObjectId("..."), "name": "Alice", "age": 25, "hobbies": ["reading", "coding"]

// Create const addBook = (title, author, pages, done) => const book = new Book( title, author, pages ); book.save((err, data) => done(err, data)); ;

const db = mongoose.connection; db.on('error', console.error.bind(console, 'connection error:')); db.once('open', () => console.log('Connected to DB')); const personSchema = new mongoose.Schema( name: type: String, required: true , age: Number, favoriteFoods: [String] ); const Person = mongoose.model('Person', personSchema); 💡 Model name = singular + capitalized. Mongoose will look for lowercase plural collection ( people ). 4. CRUD Operations (fCC exercises) Create & Save a Document const createPerson = (done) => const alice = new Person( name: 'Alice', age: 25, favoriteFoods: ['pizza'] ); alice.save((err, data) => if (err) return done(err); done(null, data); ); ; Create Many const arrayOfPeople = [ name: 'Bob', age: 30, favoriteFoods: ['burger'] , name: 'Carol', age: 22, favoriteFoods: ['sushi'] ]; Person.create(arrayOfPeople, (err, people) => if (err) return done(err); done(null, people); ); Find // Find by name Person.find( name: 'Alice' , (err, data) => done(err, data)); // Find one by _id Person.findById('65a1b2c3d4e5f67890abcdef', (err, data) => done(err, data)); Update // Find and update Person.findByIdAndUpdate( '65a1b2c3d4e5f67890abcdef', $set: age: 26 , new: true , (err, updatedDoc) => done(err, updatedDoc) ); Delete // Remove one by id Person.findByIdAndRemove('65a1b2c3d4e5f67890abcdef', (err, removedDoc) => done(err, removedDoc); ); // Remove many Person.remove( name: 'Bob' , (err, result) => done(err, result)); 5. Advanced Queries (Chain helpers) const queryChain = (done) => Person.find( favoriteFoods: 'pizza' ) .sort( name: 1 ) // ascending by name .limit(2) .select('-age') // exclude age field .exec((err, data) => done(err, data)); ; 6. Middleware & Validation Pre-save middleware personSchema.pre('save', function(next) console.log(`$this.name is being saved`); next(); ); Custom validator const userSchema = new mongoose.Schema( email: type: String, validate: validator: (v) => /.+\@.+\..+/.test(v), message: 'Invalid email format' ); 7. Common freeCodeCamp Challenges (quick reference) | Challenge | Method | |-----------|--------| | Create & save | new Model() + .save() | | Create many | Model.create([...]) | | Find by name | Model.find( name ) | | Find by ID | Model.findById(id) | | Update by ID | Model.findByIdAndUpdate(id, update, options) | | Delete by ID | Model.findByIdAndRemove(id) | | Chain helpers | .sort().limit().select().exec() | 8. Example Mini Project (fCC style) // Setup mongoose.connect(process.env.MONGO_URI); // Schema const bookSchema = new mongoose.Schema( title: type: String, required: true , author: String, pages: Number );

const Book = mongoose.model('Book', bookSchema);