Why databases back GraphQL - See It in Action

Why Databases Back GraphQL

📖 Scenario: You are building a simple GraphQL API for a bookstore. The data about books is stored in a database. You want to understand how the database supports the GraphQL queries by providing the data.

🎯 Goal: Create a basic GraphQL schema and simulate how the database data is structured and accessed to back the GraphQL queries.

📋 What You'll Learn

Create a list of books with exact titles and authors

Add a configuration variable for filtering books by minimum year

Write a GraphQL query resolver that returns books filtered by the minimum year

Complete the GraphQL schema with the query type and resolver

💡 Why This Matters

🌍 Real World

GraphQL APIs rely on databases to store and retrieve data efficiently. Understanding this connection helps build better APIs.

💼 Career

Backend developers often write GraphQL resolvers that fetch data from databases. This project shows the basic flow from data storage to API response.

1

DATA SETUP: Create the initial data structure

Create a list called books with these exact entries: {"title": "The Great Gatsby", "author": "F. Scott Fitzgerald", "year": 1925}, {"title": "1984", "author": "George Orwell", "year": 1949}, and {"title": "To Kill a Mockingbird", "author": "Harper Lee", "year": 1960}.

GraphQL

# Your code here

Hint

Use a list of dictionaries to store the books with their title, author, and year.

2

CONFIGURATION: Add a filter variable

Create a variable called min_year and set it to 1930 to filter books published from this year onward.

GraphQL

books = [
    {"title": "The Great Gatsby", "author": "F. Scott Fitzgerald", "year": 1925},
    {"title": "1984", "author": "George Orwell", "year": 1949},
    {"title": "To Kill a Mockingbird", "author": "Harper Lee", "year": 1960}
]
# Your code here

Hint

This variable will help filter the books by their publication year.

3

CORE LOGIC: Filter books by minimum year

Create a list called filtered_books that contains only the books from books where the year is greater than or equal to min_year.

GraphQL

books = [
    {"title": "The Great Gatsby", "author": "F. Scott Fitzgerald", "year": 1925},
    {"title": "1984", "author": "George Orwell", "year": 1949},
    {"title": "To Kill a Mockingbird", "author": "Harper Lee", "year": 1960}
]

min_year = 1930
# Your code here

Hint

Use a list comprehension to select books with year >= min_year.

4

COMPLETION: Define GraphQL schema and resolver

Define a GraphQL type Query with a field books that returns a list of books. Implement a resolver function called resolve_books that returns the filtered_books list.

GraphQL

books = [
    {"title": "The Great Gatsby", "author": "F. Scott Fitzgerald", "year": 1925},
    {"title": "1984", "author": "George Orwell", "year": 1949},
    {"title": "To Kill a Mockingbird", "author": "Harper Lee", "year": 1960}
]

min_year = 1930

filtered_books = [book for book in books if book["year"] >= min_year]
# Your code here

Hint

Define the GraphQL schema string and a resolver function that returns the filtered books.