NestJS Enterprise Backend APIs · Pelajaran

Dasar-Dasar GraphQL

Pahami konsep inti GraphQL, termasuk kueri, mutasi, langganan, dan bahasa definisi skema (SDL).

Dasar-Dasar GraphQL adalah pelajaran NestJS Enterprise Backend APIs gratis di CoddyKit. Ini adalah pelajaran 1 dari 3. Kamu bisa membaca pelajaran lengkapnya di bawah secara gratis — lalu praktikkan langsung di browser dengan editor kode bawaan dan tutor AI 24/7. Ini adalah bagian dari jalur belajar NestJS Enterprise Backend APIs, dan progresmu tersinkronisasi di web dan aplikasi CoddyKit. Kursus NestJS Enterprise Backend APIs mencakup 3 pelajaran total.

Bagian dari pelajaran ini belum diterjemahkan dan ditampilkan dalam bahasa Inggris.

What is GraphQL?

Welcome to GraphQL! It's a powerful query language for APIs and a runtime for fulfilling those queries with your existing data.

Think of it as asking for exactly what you need, nothing more, nothing less. This helps make your APIs efficient and flexible.

GraphQL vs. REST APIs

Traditionally, REST APIs often require multiple requests to fetch all necessary data, leading to "over-fetching" or "under-fetching".

Over-fetching: Getting more data than you need.
Under-fetching: Needing multiple requests to get all data.

GraphQL solves this by letting clients define the exact data structure they want in a single request.

The Core: GraphQL Schema

At the heart of every GraphQL API is its schema. This schema acts as a contract between the client and the server.

It defines all the data types and operations (queries, mutations, subscriptions) that clients can perform. It's like a blueprint for your API.

Defining Schemas with SDL

GraphQL schemas are written using the Schema Definition Language (SDL). It's a simple, human-readable syntax.

SDL allows you to specify your API's capabilities and data structures clearly. It's language-agnostic, meaning it works with any backend language.

schema {
  query: Query
}

type Query {
  hello: String
}

Building Blocks: Object Types

The most fundamental component of a GraphQL schema is the Object Type. It represents a type of object you can fetch from your service.

Each object type has fields, which are specific pieces of data it can hold. Fields can also be other object types!

type User {
  id: ID!
  name: String!
  email: String
  posts: [Post!]
}

type Post {
  id: ID!
  title: String!
  content: String
}

Data Types: Scalars & Lists

Scalar types are the basic building blocks that resolve to a single value, like String, Int, Float, Boolean, and ID (a unique identifier).

List types allow a field to return a list of a certain type, indicated by []. The ! means a field is Non-Null, so it must always return a value.

type Product {
  id: ID!         # Non-null ID
  name: String!   # Non-null String
  price: Float!   # Non-null Float
  tags: [String!] # List of non-null Strings
  inStock: Boolean
}

Fetching Data with Queries

Queries are how clients request data from a GraphQL server. You specify the exact fields you want to receive.

This ensures you only get the data you ask for, avoiding over-fetching common in REST APIs.

query GetProductNames {
  products {
    id
    name
  }
}

Dynamic Queries with Arguments

Fields in GraphQL can take arguments, allowing you to pass parameters to customize the data fetched. This is useful for filtering or finding specific items.

Arguments are defined in the schema and used by the client when making a query.

query GetProductById {
  product(id: "prod123") {
    id
    name
    price
  }
}

Modifying Data with Mutations

While queries are for reading data, mutations are for writing, updating, or deleting data on the server.

Like queries, mutations also specify what data to return after the operation, ensuring immediate feedback on changes.

mutation CreateNewProduct {
  createProduct(name: "New Gadget", price: 99.99) {
    id
    name
  }
}

Real-time Updates: Subscriptions

Subscriptions are a special type of operation that allows clients to receive real-time updates from the server when specific events occur.

This is perfect for features like live chat, notifications, or real-time dashboards. It typically uses WebSockets.

Schema Fundamentals Check

Consider the following GraphQL SDL snippet for an Author type:

type Author {
  id: ID!
  name: String!
  books: [Book!]
}

Which of the following statements are true about the books field?

GraphQL Fundamentals Recap

Great job! You've learned the core concepts of GraphQL:

It's a query language for APIs, offering precise data fetching.
The schema defines the API's capabilities using SDL.
You use queries to read, mutations to write, and subscriptions for real-time data.

Next, we'll see how to integrate GraphQL into a NestJS application!

Pertanyaan yang Sering Diajukan

Apakah pelajaran “Dasar-Dasar GraphQL” gratis?

Ya — teks lengkap “Dasar-Dasar GraphQL” gratis dibaca di sini di web. Untuk praktiknya secara interaktif (editor kode bawaan dan tutor AI 24/7) dan buka sisa kursus NestJS Enterprise Backend APIs, upgrade ke CoddyKit PRO. Kursus NestJS Enterprise Backend APIs mencakup 3 pelajaran total.

Apa yang akan aku pelajari di “Dasar-Dasar GraphQL”?

Pahami konsep inti GraphQL, termasuk kueri, mutasi, langganan, dan bahasa definisi skema (SDL). Kamu berlatih NestJS Enterprise Backend APIs dengan kode praktik yang langsung kamu jalankan di browser, dan tutor AI 24/7 menjawab pertanyaanmu saat kamu mengerjakan pelajaran ini.

Apakah aku perlu pengalaman untuk memulai NestJS Enterprise Backend APIs?

Tidak diperlukan pengalaman sebelumnya. NestJS Enterprise Backend APIs di CoddyKit dirancang untuk pemula hingga pelajar tingkat lanjut, jadi kamu bisa memulai di sini atau dari awal dan belajar sesuai kecepatan kamu sendiri. Ini adalah pelajaran 1 dari 3.

Berapa lama pelajaran “Dasar-Dasar GraphQL” memakan waktu?

Sebagian besar pelajaran CoddyKit memakan waktu sekitar 5–10 menit. Setiap pelajaran ringkas dan interaktif, jadi kamu membuat kemajuan stabil dan melanjutkan dari tempat kamu tinggalkan di web dan aplikasi.

Bisakah aku menulis dan menjalankan kode dalam pelajaran NestJS Enterprise Backend APIs ini?

Ya. Setiap pelajaran NestJS Enterprise Backend APIs menyertakan editor kode bawaan, jadi kamu menulis dan menjalankan kode nyata langsung di browser dan mendapatkan umpan balik AI instan — tidak diperlukan penyiapan lokal.

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