MongoDB Basics — Complete Guide
MongoDB Basics — Complete Guide: free step-by-step lesson with examples, common mistakes, and interview tips — part of MEAN Stack Tutorial on Toolliyo Academy.
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MEAN Stack Tutorial · Lesson 41 of 100
MongoDB Basics
Stack → Projects
Stack · 1 — Pieces · ~6 min · MEAN — & Databases
What is this?
MongoDB stores BSON documents in collections within databases — MeanVerse uses meanverse DB with accounts, users, orders collections.
Why should you care?
MEAN apps map JSON API payloads directly to documents without ORM impedance mismatch.
See it live — copy this example
Paste into your MeanVerse project (Angular + Express + MongoDB), then run with ng serve / node / mongosh as noted.
// mongosh
use meanverse
db.accounts.insertOne({
_id: ObjectId(),
tenantId: 't_acme',
name: 'Operating',
balanceCents: 250000,
currency: 'USD',
createdAt: new Date()
})
db.accounts.find({ tenantId: 't_acme' }).sort({ createdAt: -1 })What happened?
- insertOne adds document with optional ObjectId.
- find filter matches tenantId.
- sort -1 is newest first.
- Fields can vary per document.
Practice next
- Connect mongosh to local or Atlas cluster.
- Insert sample account and user documents.
- Query with find, projection { name: 1, balanceCents: 1 }.
- Add compound index on tenantId + name.
- Compare findOne vs find().limit(1) performance.
Remember
Database > collection > document hierarchy. Queries use JSON-like filter objects. Design for MeanVerse tenant isolation early.
E-commerce catalog
Products have variants array; SQL would need join tables.
Outcome: One product document embeds SKUs for fast PDP API.
Interview prep for this lesson
Practice these questions aloud after reading—each links to a full structured answer.
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