GraphQL Playground and tools - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is GraphQL Playground?

GraphQL Playground is an interactive tool that helps you write, test, and explore GraphQL queries and mutations easily in a friendly interface.

beginner

Name two popular tools used for testing GraphQL APIs.

Two popular tools are GraphQL Playground and GraphiQL. Both provide interactive environments to run and test GraphQL queries.

intermediate

How does GraphQL Playground help developers?

It helps by showing real-time query results, auto-completing fields, displaying schema documentation, and allowing easy debugging of GraphQL APIs.

intermediate

What feature in GraphQL Playground shows the structure of the API?

The Schema Explorer feature shows the API's types, queries, mutations, and subscriptions, helping users understand what data they can request.

beginner

Can GraphQL Playground be used with any GraphQL server?

Yes, GraphQL Playground can connect to any GraphQL server endpoint, making it a versatile tool for testing and exploring different GraphQL APIs.

What is the main purpose of GraphQL Playground?

A To interactively write and test GraphQL queries

B To store data in a database

C To design website layouts

D To compile GraphQL code into JavaScript

GraphQL Playground is designed to help users write and test GraphQL queries interactively.

Which feature in GraphQL Playground helps you understand the API's data structure?

A Query History

B Schema Explorer

C Mutation Runner

D Code Formatter

Schema Explorer shows the API's types and available queries, helping users understand the data structure.

GraphQL Playground can be used with which of the following?

A Any GraphQL server endpoint

B Only Apollo GraphQL servers

C Only REST APIs

D Only local databases

GraphQL Playground works with any GraphQL server endpoint.

Which of these is NOT a feature of GraphQL Playground?

A Auto-completion of query fields

B Real-time query results

C Schema documentation display

D Automatic database backups

GraphQL Playground does not perform database backups; it focuses on query testing and exploration.

GraphiQL is:

A A web server

B A database management system

C A tool similar to GraphQL Playground

D A programming language

GraphiQL is another interactive tool for testing GraphQL queries, similar to GraphQL Playground.

Explain what GraphQL Playground is and how it helps when working with GraphQL APIs.

Think about how you test and explore data requests in GraphQL.

List and describe two tools used to test GraphQL queries and mention one key feature of each.

Both tools help you write and run queries but may have slightly different interfaces.

Practice

1. What is the main purpose of GraphQL Playground?

easy

A. To write and test GraphQL queries easily without extra setup

B. To store large amounts of data permanently

C. To replace SQL databases with a new storage system

D. To create user interfaces for mobile apps

Solution

1. Step 1: Understand GraphQL Playground's role

   GraphQL Playground is a tool designed to help users write and test GraphQL queries interactively.

2. Step 2: Compare options with this role

   Only To write and test GraphQL queries easily without extra setup describes this purpose correctly; others describe unrelated functions.

3. Final Answer:

   To write and test GraphQL queries easily without extra setup -> Option A

4. Quick Check:

   GraphQL Playground = Query testing tool [OK]

Hint: Think: Playground means a place to try things out [OK]

Common Mistakes:

• Confusing Playground with database storage
• Thinking it builds app interfaces
• Assuming it replaces databases

2. Which of the following is the correct way to start a query in GraphQL Playground?

easy

A. SELECT * FROM user

B. query { user { id name } }

C. { user id name }

D. GET user { id, name }

Solution

1. Step 1: Recall GraphQL query syntax

   GraphQL queries start with the keyword query followed by the selection set in braces.

2. Step 2: Check each option's syntax

   query { user { id name } } uses correct GraphQL syntax. Options B and D use SQL or HTTP-like syntax, and C misses the query keyword and braces.

3. Final Answer:

   query { user { id name } } -> Option B

4. Quick Check:

   GraphQL queries start with 'query' [OK]

Hint: GraphQL queries start with 'query' keyword and braces [OK]

Common Mistakes:

• Using SQL syntax instead of GraphQL
• Omitting the 'query' keyword
• Missing braces around fields

3. Given this GraphQL query in Playground:

query { book(id: "1") { title author } }

What will the result look like if the book with id "1" has title "GraphQL Guide" and author "Anna"?

medium

A. { "book": { "title": "GraphQL Guide", "author": "Anna" } }

B. { "data": { "book": ["GraphQL Guide", "Anna"] } }

C. { "data": { "book": { "title": "GraphQL Guide", "author": "Anna" } } }

D. { "data": { "book": { "name": "GraphQL Guide", "writer": "Anna" } } }

Solution

1. Step 1: Understand GraphQL response format

   GraphQL responses wrap requested data inside a top-level "data" object matching the query structure.

2. Step 2: Match query fields with response

   The query asks for title and author fields of book. { "data": { "book": { "title": "GraphQL Guide", "author": "Anna" } } } matches this exactly with correct field names and structure.

3. Final Answer:

   { "data": { "book": { "title": "GraphQL Guide", "author": "Anna" } } } -> Option C

4. Quick Check:

   GraphQL response = data wrapper + requested fields [OK]

Hint: GraphQL results always wrap data inside a 'data' object [OK]

Common Mistakes:

• Omitting the 'data' wrapper in response
• Using wrong field names in response
• Returning arrays instead of objects

4. You wrote this query in GraphQL Playground:

query { user(id: 5) { name email } }

But you get an error. What is the likely cause?

medium

A. GraphQL Playground does not support arguments

B. The query keyword is missing

C. Field names must be uppercase

D. The id argument should be a string, so it needs quotes

Solution

1. Step 1: Check argument types in GraphQL

   GraphQL requires string arguments to be in quotes. Here, id is likely a string but given without quotes.

2. Step 2: Verify other options

   The query keyword is present, field names are case-sensitive but lowercase is valid, and Playground supports arguments. So only The id argument should be a string, so it needs quotes explains the error.

3. Final Answer:

   The id argument should be a string, so it needs quotes -> Option D

4. Quick Check:

   String args need quotes in GraphQL [OK]

Hint: Put quotes around string arguments in queries [OK]

Common Mistakes:

• Leaving string arguments unquoted
• Assuming Playground lacks argument support
• Changing field name case incorrectly

5. You want to explore a new GraphQL API using Playground. Which feature helps you see all available types and fields without writing a query?

hard

A. The Schema Explorer sidebar showing types and fields

B. The Query History panel listing past queries

C. The Response Formatter that beautifies output

D. The Variable Editor for setting query variables

Solution

1. Step 1: Identify features for schema exploration

   GraphQL Playground includes a Schema Explorer sidebar that lists all types, queries, mutations, and fields available in the API.

2. Step 2: Compare other options

   Query History shows past queries, Response Formatter beautifies output, Variable Editor manages variables. Only Schema Explorer shows API schema details.

3. Final Answer:

   The Schema Explorer sidebar showing types and fields -> Option A

4. Quick Check:

   Schema Explorer = view API types and fields [OK]

Hint: Use Schema Explorer to browse API structure easily [OK]

Common Mistakes:

• Confusing Query History with schema browsing
• Thinking Response Formatter shows schema
• Assuming Variable Editor lists fields