OpenAPI Specification (Swagger) in Rest API - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to specify the OpenAPI version in the specification.

Rest API

{
  "openapi": "[1]",
  "info": {
    "title": "Sample API",
    "version": "1.0.0"
  }
}

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

A1.0.0

B3.0.0

C2.0.0

D4.0.0

Attempts:

3 left

💡 Hint

Common Mistakes

Using Swagger 2.0 version number instead of OpenAPI 3.0.0

Putting the version number in the wrong field

The openapi field specifies the OpenAPI version. Version 3.0.0 is the correct format for OpenAPI 3 specifications.

2fill in blank

medium

Complete the code to define the HTTP method for the API path.

Rest API

"paths": {
  "/users": {
    "[1]": {
      "summary": "Get list of users",
      "responses": {
        "200": {
          "description": "A JSON array of user names"
        }
      }
    }
  }
}

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

Aget

Bpost

Cput

Ddelete

Attempts:

3 left

💡 Hint

Common Mistakes

Using POST instead of GET for retrieving data

Capitalizing the HTTP method (should be lowercase)

The HTTP method get is used to retrieve data, such as a list of users.

3fill in blank

hard

Fix the error in the response content type definition.

Rest API

"responses": {
  "200": {
    "description": "Successful response",
    "content": {
      "[1]": {
        "schema": {
          "type": "array",
          "items": {
            "type": "string"
          }
        }
      }
    }
  }
}

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

Aapplication/json

Bapplication/xml

Ctext/plain

Dimage/png

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'text/plain' instead of 'application/json'

Using image content types for JSON data

The content type application/json is used for JSON responses, which is standard for APIs returning arrays of strings.

4fill in blank

hard

Fill both blanks to define a parameter for a path variable named 'userId' of type string.

Rest API

"parameters": [
  {
    "name": "[1]",
    "in": "[2]",
    "required": true,
    "schema": {
      "type": "string"
    }
  }
]

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

AuserId

Bquery

Cpath

Did

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'query' instead of 'path' for path parameters

Using a different name than the path variable

The parameter name is userId and it is located in the path of the URL.

5fill in blank

hard

Fill all three blanks to define a schema property named 'age' of type integer with a minimum value of 0.

Rest API

"properties": {
  "[1]": {
    "type": "[2]",
    "minimum": [3]
  }
}

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

Aage

Bstring

C0

Dinteger

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'string' type for age

Not setting minimum value or setting it as a string

The property name is age, its type is integer, and the minimum allowed value is 0.

Practice

1. What is the main purpose of the OpenAPI Specification in REST APIs?

easy

A. To store user data securely

B. To execute API requests automatically

C. To replace the need for API servers

D. To describe the API endpoints, methods, and data formats in a standard way

Solution

1. Step 1: Understand OpenAPI's role

   OpenAPI Specification is designed to describe APIs clearly and consistently.

2. Step 2: Identify the correct purpose

   It documents endpoints, HTTP methods, parameters, and data formats for APIs.

3. Final Answer:

   To describe the API endpoints, methods, and data formats in a standard way -> Option D

4. Quick Check:

   OpenAPI = API description standard [OK]

Hint: OpenAPI is for describing APIs, not running or storing data [OK]

Common Mistakes:

• Confusing OpenAPI with API execution tools
• Thinking OpenAPI stores user data
• Believing OpenAPI replaces servers

2. Which of the following is the correct way to define an HTTP GET method for the path /users in OpenAPI YAML?

easy

A. paths:
get:
/users:
summary: Get all users

B. paths:
/users:
get:
summary: Get all users

C. get:
paths:
/users:
summary: Get all users

D. paths:
/users:
post:
summary: Get all users

Solution

1. Step 1: Check OpenAPI path structure

   Paths are keys under paths, then HTTP methods like get are nested under each path.

2. Step 2: Validate correct nesting and method

   paths: /users: get: summary: Get all users correctly places /users under paths and get under /users.

3. Final Answer:

   paths: /users: get: summary: Get all users -> Option B

4. Quick Check:

   Paths > /users > get [OK]

Hint: Remember: paths > endpoint > method > details [OK]

Common Mistakes:

• Swapping method and path levels
• Using wrong HTTP method for GET
• Incorrect YAML indentation

3. Given this OpenAPI snippet, what is the response code defined for a successful GET request to /items?

paths:
  /items:
    get:
      responses:
        '200':
          description: Successful response
        '404':
          description: Not found

medium

A. 200

B. 201

C. 500

D. 404

Solution

1. Step 1: Locate response codes under GET method

   The snippet shows responses under get for /items.

2. Step 2: Identify success response code

   Code 200 is labeled as "Successful response", indicating success.

3. Final Answer:

   200 -> Option A

4. Quick Check:

   Success = 200 HTTP code [OK]

Hint: Success responses usually use 200 code [OK]

Common Mistakes:

• Choosing 404 as success code
• Confusing 201 (created) with 200
• Ignoring response codes listed

4. Identify the error in this OpenAPI YAML snippet:

paths:
  /login:
    post:
      summary: User login
      responses:
        200:
          description: Login successful

medium

A. Summary field is not allowed under POST

B. Missing requestBody for POST method

C. Response code 200 should be a string '200', not a number

D. Path should start with a capital letter

Solution

1. Step 1: Check response code format

   OpenAPI requires response codes as strings, e.g., '200', not numbers.

2. Step 2: Verify other fields

   Summary is allowed; requestBody is optional; path case is flexible.

3. Final Answer:

   Response code 200 should be a string '200', not a number -> Option C

4. Quick Check:

   Response codes must be strings [OK]

Hint: Always quote response codes as strings in YAML [OK]

Common Mistakes:

• Using numeric response codes
• Assuming requestBody is mandatory
• Thinking summary is invalid

5. You want to document an API that returns a list of products with optional filtering by category. Which OpenAPI feature helps you define the optional category filter parameter for the GET /products endpoint?

hard

A. Use a query parameter with required: false under the GET method

B. Add a path parameter named category in the URL

C. Include category in the requestBody schema

D. Define category as a header parameter

Solution

1. Step 1: Understand parameter types

   Optional filters are usually query parameters, not path or header parameters.

2. Step 2: Define optional query parameter

   Set required: false for the category query parameter under GET.

3. Final Answer:

   Use a query parameter with required: false under the GET method -> Option A

4. Quick Check:

   Optional filters = query params with required false [OK]

Hint: Filters usually go as optional query parameters [OK]

Common Mistakes:

• Using path parameters for optional filters
• Putting filters in requestBody for GET
• Defining filters as headers