Error classification in GraphQL - Mini Project: Build & Apply

Error classification

📖 Scenario: You work as a data analyst for a customer support team. They want to classify error messages from their system logs into categories to understand common problems.

🎯 Goal: Build a simple GraphQL query that returns error messages and their classification categories from a predefined dataset.

📋 What You'll Learn

Create a list of error messages with their types

Add a variable to filter errors by a specific type

Write a GraphQL query to select errors matching the filter

Display the filtered error messages and their categories

💡 Why This Matters

🌍 Real World

Classifying error messages helps support teams quickly identify and fix common problems in software systems.

💼 Career

Understanding how to filter and query data with GraphQL is useful for backend developers and data analysts working with APIs.

1

Create the error messages dataset

Create a list called errors with these exact entries: { id: 1, message: "Timeout error", category: "Network" }, { id: 2, message: "Null pointer exception", category: "Code" }, { id: 3, message: "Disk full", category: "Storage" }, { id: 4, message: "Timeout error", category: "Network" }.

GraphQL

# Your code here

Hint

Use an array of objects with id, message, and category keys.

2

Add a filter variable for category

Create a variable called filterCategory and set it to the string "Network".

GraphQL

const errors = [
  { id: 1, message: "Timeout error", category: "Network" },
  { id: 2, message: "Null pointer exception", category: "Code" },
  { id: 3, message: "Disk full", category: "Storage" },
  { id: 4, message: "Timeout error", category: "Network" }
];

# Your code here

Hint

Use a constant string variable to hold the category filter.

3

Write a GraphQL query to filter errors by category

Write a GraphQL query called getErrorsByCategory that takes a category argument of type String! and returns id, message, and category fields for errors matching the argument.

GraphQL

const errors = [
  { id: 1, message: "Timeout error", category: "Network" },
  { id: 2, message: "Null pointer exception", category: "Code" },
  { id: 3, message: "Disk full", category: "Storage" },
  { id: 4, message: "Timeout error", category: "Network" }
];

const filterCategory = "Network";

# Your code here

Hint

Define a GraphQL query type with a category argument and filter the errors array in the resolver.

4

Display the filtered error messages and categories

Write a console.log statement that prints the result of calling resolvers.Query.getErrorsByCategory with { category: filterCategory } as argument.

GraphQL

const errors = [
  { id: 1, message: "Timeout error", category: "Network" },
  { id: 2, message: "Null pointer exception", category: "Code" },
  { id: 3, message: "Disk full", category: "Storage" },
  { id: 4, message: "Timeout error", category: "Network" }
];

const filterCategory = "Network";

const typeDefs = `
  type Error {
    id: Int
    message: String
    category: String
  }

  type Query {
    getErrorsByCategory(category: String!): [Error]
  }
`;

const resolvers = {
  Query: {
    getErrorsByCategory: (_, { category }) => errors.filter(error => error.category === category)
  }
};

# Your code here

Hint

Call the resolver function with null as first argument and an object with category: filterCategory as second argument, then print the result.