Why advanced features improve flexibility in GraphQL - See It in Action

Why advanced features improve flexibility

📖 Scenario: You are building a simple GraphQL API for a bookstore. The bookstore wants to manage its books and authors. Initially, you will create a basic data structure to hold books and authors. Then, you will add a configuration to filter books by a minimum rating. Next, you will write a GraphQL query to fetch books that meet the rating criteria. Finally, you will complete the schema with a query type that supports this filtering.

🎯 Goal: Build a GraphQL schema that demonstrates how advanced features like arguments and filtering improve flexibility in querying data.

📋 What You'll Learn

Create a list of books with exact fields and values

Add a variable for minimum rating filter

Write a GraphQL query that filters books by minimum rating

Complete the GraphQL schema with a query type supporting the filter

💡 Why This Matters

🌍 Real World

GraphQL APIs often need flexible queries to allow clients to request exactly the data they want with filters and arguments.

💼 Career

Understanding how to use arguments and define flexible schemas is essential for backend developers working with GraphQL to build scalable and maintainable APIs.

1

DATA SETUP: Create a list of books

Create a variable called books that is a list of dictionaries. Each dictionary should have these exact keys and values: {'id': 1, 'title': 'GraphQL Basics', 'author': 'Alice', 'rating': 4.5}, {'id': 2, 'title': 'Advanced GraphQL', 'author': 'Bob', 'rating': 4.8}, and {'id': 3, 'title': 'GraphQL in Practice', 'author': 'Charlie', 'rating': 4.2}.

GraphQL

# Create the list of books with exact entries
# Your code here

Hint

Use a list with dictionaries exactly as shown.

2

CONFIGURATION: Add a minimum rating filter

Create a variable called min_rating and set it to 4.5.

GraphQL

books = [
    {'id': 1, 'title': 'GraphQL Basics', 'author': 'Alice', 'rating': 4.5},
    {'id': 2, 'title': 'Advanced GraphQL', 'author': 'Bob', 'rating': 4.8},
    {'id': 3, 'title': 'GraphQL in Practice', 'author': 'Charlie', 'rating': 4.2}
]
# Create a variable called min_rating and set it to 4.5
# Your code here

Hint

Just assign 4.5 to min_rating.

3

CORE LOGIC: Write a GraphQL query with rating filter

Write a GraphQL query string called query that fetches books with a rating greater than or equal to min_rating. The query should be named GetBooks and accept a variable $minRating of type Float. It should request id, title, author, and rating fields for books filtered by rating_gte: $minRating.

GraphQL

books = [
    {'id': 1, 'title': 'GraphQL Basics', 'author': 'Alice', 'rating': 4.5},
    {'id': 2, 'title': 'Advanced GraphQL', 'author': 'Bob', 'rating': 4.8},
    {'id': 3, 'title': 'GraphQL in Practice', 'author': 'Charlie', 'rating': 4.2}
]

min_rating = 4.5

# Write a GraphQL query string named query with variable $minRating of type Float
# that fetches books with rating_gte: $minRating and fields id, title, author, rating
# Your code here

Hint

Use triple quotes for the query string and include the variable and filter exactly as shown.

4

COMPLETION: Define the GraphQL schema with query type

Define a GraphQL schema string called schema that includes a Book type with fields id (Int), title (String), author (String), and rating (Float). Also define a Query type with a books field that accepts an optional argument rating_gte of type Float and returns a list of Book. Assign the full schema SDL string to schema.

GraphQL

books = [
    {'id': 1, 'title': 'GraphQL Basics', 'author': 'Alice', 'rating': 4.5},
    {'id': 2, 'title': 'Advanced GraphQL', 'author': 'Bob', 'rating': 4.8},
    {'id': 3, 'title': 'GraphQL in Practice', 'author': 'Charlie', 'rating': 4.2}
]

min_rating = 4.5

query = '''
query GetBooks($minRating: Float) {
  books(rating_gte: $minRating) {
    id
    title
    author
    rating
  }
}
'''

# Define the GraphQL schema string called schema with Book and Query types
# Your code here

Hint

Write the schema SDL string exactly with Book and Query types as shown.