Role-based access control in GraphQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a role-based access control directive in GraphQL schema.

GraphQL

directive @auth(role: String!) on [1]

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

AQUERY

BSCHEMA

CMUTATION

DFIELD_DEFINITION

Attempts:

3 left

💡 Hint

Common Mistakes

Using QUERY or MUTATION which are operation types, not directive locations.

Using SCHEMA which applies directive to the whole schema, not specific fields.

The @auth directive is applied on field definitions to enforce role checks on specific fields.

2fill in blank

medium

Complete the resolver function to check if user role matches the required role.

GraphQL

if (user.role !== [1]) {
  throw new Error('Access denied');
}

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

Ainfo.role

Bargs.role

Ccontext.requiredRole

Dparent.role

Attempts:

3 left

💡 Hint

Common Mistakes

Using args.role which is input arguments, not the required role.

Using info.role or parent.role which are unrelated to access control here.

The required role is typically passed in the context for access control checks.

3fill in blank

hard

Fix the error in the directive resolver to correctly get the role argument.

GraphQL

const role = directiveNode.arguments.find(arg => arg.name.value === [1]).value.value;

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

A'role'

Brole

C"role"

Drole.value

Attempts:

3 left

💡 Hint

Common Mistakes

Using unquoted role which causes a reference error.

Using role.value which is incorrect for the argument name.

The argument name is a string literal, so it must be enclosed in quotes.

4fill in blank

hard

Fill both blanks to define a GraphQL schema with a protected query field using the auth directive.

GraphQL

""
type Query {
  secretData: String [1] @auth(role: [2])
}
"""

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

A!

BString

C"ADMIN"

DInt

Attempts:

3 left

💡 Hint

Common Mistakes

Omitting the exclamation mark which makes the field nullable.

Not quoting the role name which causes syntax errors.

The field is non-nullable (hence !) and the auth directive requires the role "ADMIN".

5fill in blank

hard

Fill all three blanks to implement a resolver that checks user role and returns data if authorized.

GraphQL

const resolver = (parent, args, context, info) => {
  if (context.user.role !== [1]) {
    throw new Error([2]);
  }
  return [3];
};

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

A"ADMIN"

B"Access denied"

Cparent.secretData

D"User"

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect role strings or error messages.

Returning wrong data or not throwing error on unauthorized access.

The resolver checks if the user role is "ADMIN", throws an error message "Access denied" if not, and returns the secret data from parent.secretData.

Practice

1. What is the main purpose of role-based access control (RBAC) in GraphQL APIs?

easy

A. To format the response data

B. To speed up query execution

C. To restrict data access based on user roles

D. To cache query results

Solution

1. Step 1: Understand RBAC concept

   RBAC limits what data users can access depending on their assigned roles.

2. Step 2: Identify RBAC purpose in GraphQL

   In GraphQL, RBAC ensures users only see or modify data allowed by their role.

3. Final Answer:

   To restrict data access based on user roles -> Option C

4. Quick Check:

   RBAC = restrict access by role [OK]

Hint: RBAC controls who can see or change data [OK]

Common Mistakes:

• Confusing RBAC with performance optimization
• Thinking RBAC formats data output
• Assuming RBAC caches data

2. Which of the following is the correct way to apply a role-based directive in a GraphQL schema to restrict a query to admins only?

easy

A. type Query { users: [User] @hasRole(role: "admin") }

B. type Query { users: [User] @roleCheck("admin") }

C. type Query { users: [User] @auth(role: "admin") }

D. type Query { users: [User] @access(role = admin) }

Solution

1. Step 1: Identify correct directive syntax

   The standard directive for role checks is @hasRole with a role argument as a string.

2. Step 2: Match syntax to options

   type Query { users: [User] @hasRole(role: "admin") } uses @hasRole(role: "admin"), which is the correct syntax.

3. Final Answer:

   type Query { users: [User] @hasRole(role: "admin") } -> Option A

4. Quick Check:

   @hasRole(role: "admin") syntax correct [OK]

Hint: Look for @hasRole with role as string argument [OK]

Common Mistakes:

• Using incorrect directive names like @auth or @roleCheck
• Missing quotes around role name
• Using = instead of : in directive arguments

3. Given this GraphQL query protected by @hasRole(role: "editor"), what will happen if a user with role "viewer" tries to run it?

query { editArticle(id: "123") { title content } }

medium

A. The query returns an authorization error

B. The query returns empty data with no error

C. The query returns the article data as usual

D. The query causes a server crash

Solution

1. Step 1: Understand role restriction effect

   @hasRole(role: "editor") restricts access to users with the editor role only.

2. Step 2: Check user role against required role

   User has role "viewer", which does not match "editor", so access is denied.

3. Final Answer:

   The query returns an authorization error -> Option A

4. Quick Check:

   Role mismatch = authorization error [OK]

Hint: Role mismatch causes authorization error [OK]

Common Mistakes:

• Assuming query returns data anyway
• Thinking query returns empty data silently
• Believing server crashes on role denial

4. You wrote this schema directive to restrict a mutation to admins:

type Mutation { deleteUser(id: ID!): Boolean @hasRole(role: admin) }

Why does this cause a syntax error?

medium

A. The directive name @hasRole is invalid

B. ID! is not a valid type

C. Mutation type cannot have directives

D. The role value admin is missing quotes

Solution

1. Step 1: Check directive argument syntax

   Directive arguments require string values in quotes, e.g., role: "admin".

2. Step 2: Identify missing quotes error

   Here, role: admin lacks quotes, causing a syntax error.

3. Final Answer:

   The role value admin is missing quotes -> Option D

4. Quick Check:

   Directive string args need quotes [OK]

Hint: Always put role names in quotes in directives [OK]

Common Mistakes:

• Thinking directive names are wrong
• Believing directives can't be on mutations
• Misunderstanding ID! type syntax

5. You want to allow only users with roles "admin" or "manager" to update product prices. Which schema directive setup correctly enforces this in GraphQL?

hard

A. type Mutation { updatePrice(id: ID!, price: Float): Product @hasAnyRole(roles: ["admin", "manager"]) }

B. type Mutation { updatePrice(id: ID!, price: Float): Product @hasRole(role: ["admin", "manager"]) }

C. type Mutation { updatePrice(id: ID!, price: Float): Product @hasRole(role: "admin") @hasRole(role: "manager") }

D. type Mutation { updatePrice(id: ID!, price: Float): Product @hasRole(roles: "admin,manager") }

Solution

1. Step 1: Understand multi-role directive syntax

   @hasRole accepts an array of roles to allow multiple roles access.

2. Step 2: Evaluate options for correct syntax

   type Mutation { updatePrice(id: ID!, price: Float): Product @hasRole(role: ["admin", "manager"]) } uses @hasRole(role: ["admin", "manager"]), which correctly passes an array of roles.

3. Step 3: Identify incorrect options

   type Mutation { updatePrice(id: ID!, price: Float): Product @hasRole(roles: "admin,manager") } passes a string, not an array; C uses multiple directives which may not combine logically; A uses a non-standard directive @hasAnyRole.

4. Final Answer:

   type Mutation { updatePrice(id: ID!, price: Float): Product @hasRole(role: ["admin", "manager"]) } -> Option B

5. Quick Check:

   Array of roles in @hasRole = correct [OK]

Hint: Use array syntax for multiple roles in @hasRole [OK]

Common Mistakes:

• Passing roles as comma string instead of array
• Using multiple @hasRole directives expecting OR logic
• Using non-standard directive names