Code generation from schema in GraphQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a GraphQL type for a User with an ID field.

GraphQL

type User { id: [1] }

Drag options to blanks, or click blank then click option'

AInt

BString

CID!

DBoolean

Attempts:

3 left

💡 Hint

Common Mistakes

Using String instead of ID for unique identifiers.

Forgetting the exclamation mark to make the field required.

The ID! type is used for unique identifiers and the exclamation mark means it is required.

2fill in blank

medium

Complete the code to add a name field of type String to the User type.

GraphQL

type User { id: ID! name: [1] }

Drag options to blanks, or click blank then click option'

AString!

BInt

CBoolean

DFloat

Attempts:

3 left

💡 Hint

Common Mistakes

Using Int or Boolean instead of String for text.

Omitting the exclamation mark if the field is required.

The String! type means the name is a required string field.

3fill in blank

hard

Fix the error in the schema by completing the field type for posts as a list of Post types.

GraphQL

type User { posts: [[1]!]! }

Drag options to blanks, or click blank then click option'

ABoolean

BString

CID

DPost

Attempts:

3 left

💡 Hint

Common Mistakes

Using scalar types like String or ID instead of the Post type.

Forgetting to add exclamation marks for non-nullability.

The posts field is a non-nullable list of non-nullable Post objects.

4fill in blank

hard

Fill both blanks to define a Query type with a user field that takes an ID argument and returns a User.

GraphQL

type Query { user(id: [1]!): [2] }

Drag options to blanks, or click blank then click option'

AID

BString

CUser

DBoolean

Attempts:

3 left

💡 Hint

Common Mistakes

Using String instead of ID for the argument.

Returning a scalar type instead of the User type.

The user query takes a non-nullable ID argument and returns a User type.

5fill in blank

hard

Fill all three blanks to define a Mutation type with a createUser field that takes a name argument and returns a User.

GraphQL

type Mutation { createUser(name: [1]!): [2] } input CreateUserInput { name: [3]! }

Drag options to blanks, or click blank then click option'

AString

BUser

DID

Attempts:

3 left

💡 Hint

Common Mistakes

Using ID instead of String for the name argument.

Returning a scalar type instead of User.

Mismatching input field types.

The createUser mutation takes a non-nullable String name argument and returns a User. The input type CreateUserInput also defines a required String name field.

Practice

1. What is the main purpose of code generation from a GraphQL schema?

easy

A. To delete unused database tables

B. To manually write all database queries

C. To automatically create code based on the GraphQL schema

D. To convert GraphQL queries into HTML pages

Solution

1. Step 1: Understand code generation concept

   Code generation means creating code automatically from a source, here the GraphQL schema.

2. Step 2: Identify the purpose in GraphQL context

   In GraphQL, code generation helps create types and queries automatically from the schema to save time.

3. Final Answer:

   To automatically create code based on the GraphQL schema -> Option C

4. Quick Check:

   Code generation = automatic code creation [OK]

Hint: Code generation means automatic code creation from schema [OK]

Common Mistakes:

• Thinking code generation means manual coding
• Confusing code generation with deleting tables
• Assuming it converts queries to HTML

2. Which of the following is the correct way to specify the schema file in a GraphQL code generator config?

easy

A. "schema => './schema.graphql'"

B. "schema = './schema.graphql'"

C. "schema: schema.graphql"

D. "schema: './schema.graphql'"

Solution

1. Step 1: Recall config syntax for GraphQL code generator

   The config uses key-value pairs with colon and string paths in quotes.

2. Step 2: Identify correct syntax

   "schema: './schema.graphql'" uses colon and quotes correctly: "schema: './schema.graphql'".

3. Final Answer:

   "schema: './schema.graphql'" -> Option D

4. Quick Check:

   Config uses colon and quotes for paths [OK]

Hint: Config uses colon and quotes for file paths [OK]

Common Mistakes:

• Using equals sign instead of colon
• Omitting quotes around file path
• Using arrow syntax which is invalid here

3. Given this config snippet:

{
  schema: './schema.graphql',
  generates: {
    './src/types.ts': { plugins: ['typescript'] }
  }
}

What will be generated after running the code generator?

medium

A. A JavaScript file with database connection code

B. A TypeScript file with types matching the GraphQL schema

C. An HTML file showing the schema documentation

D. A JSON file with raw schema data

Solution

1. Step 1: Analyze the config's generates section

   The config says to generate './src/types.ts' using the 'typescript' plugin.

2. Step 2: Understand what the 'typescript' plugin does

   This plugin creates TypeScript types based on the GraphQL schema.

3. Final Answer:

   A TypeScript file with types matching the GraphQL schema -> Option B

4. Quick Check:

   typescript plugin = TypeScript types file [OK]

Hint: Plugin name hints the generated file type [OK]

Common Mistakes:

• Confusing TypeScript with JavaScript output
• Expecting HTML or JSON instead of types
• Ignoring the plugin specified

4. You run the GraphQL code generator but get an error: "Cannot find schema file './schema.graphql'". What is the most likely cause?

medium

A. The schema file path in the config is incorrect or file is missing

B. The code generator does not support GraphQL schemas

C. The output file path is invalid

D. The plugins array is empty

Solution

1. Step 1: Understand the error message

   The error says it cannot find the schema file at the given path.

2. Step 2: Identify the cause

   This usually means the path is wrong or the file does not exist at that location.

3. Final Answer:

   The schema file path in the config is incorrect or file is missing -> Option A

4. Quick Check:

   File not found = wrong path or missing file [OK]

Hint: Check schema file path and existence first [OK]

Common Mistakes:

• Blaming plugins or output path
• Assuming code generator lacks schema support
• Ignoring file system errors

5. You want to generate both TypeScript types and React hooks from your GraphQL schema. Which config snippet correctly sets this up?

hard

A. {
schema: './schema.graphql',
generates: {
'./src/types.ts': { plugins: ['typescript'] },
'./src/hooks.ts': { plugins: ['typescript-react-apollo'] }
}
}

B. {
schema: './schema.graphql',
generates: {
'./src/types.ts': { plugins: ['typescript-react-apollo'] },
'./src/hooks.ts': { plugins: ['typescript'] }
}
}

C. {
schema: './schema.graphql',
generates: {
'./src/types.ts': { plugins: ['react-hooks'] },
'./src/hooks.ts': { plugins: ['typescript'] }
}
}

D. {
schema: './schema.graphql',
generates: {
'./src/types.ts': { plugins: ['typescript'] },
'./src/hooks.ts': { plugins: ['react-hooks'] }
}
}

Solution

1. Step 1: Identify plugins for types and hooks

   'typescript' plugin generates TypeScript types; 'typescript-react-apollo' generates React Apollo hooks.

2. Step 2: Match plugins to correct output files

   Types go to './src/types.ts' with 'typescript'; hooks go to './src/hooks.ts' with 'typescript-react-apollo'.

3. Final Answer:

   Config with 'typescript' for types and 'typescript-react-apollo' for hooks -> Option A

4. Quick Check:

   Correct plugins match output files [OK]

Hint: Match plugins to output files by their purpose [OK]

Common Mistakes:

• Swapping plugins between files
• Using non-existent plugins like 'react-hooks'
• Missing one of the required plugins