7. OpenAPI Basics

This file supports the OpenAPI/Swagger segment of Week 2.

Explain the role of OpenAPI

• OpenAPI is a contract for your HTTP API.
• It describes:

  • Which paths and methods exist.
  • What parameters and request bodies they accept.
  • What responses (status codes and schemas) they return.
• Tools can use it to:

  • Generate documentation.
  • Generate client/server code.
  • Validate requests and responses.

Minimal example for GET /api/snippets

Use a concise YAML snippet in the session:

paths:
  /api/snippets:
    get:
      summary: List public code snippets
      responses:
        "200":
          description: List of snippets
          content:
            application/json:
              schema:
                type: array
                items:
                  $ref: "#/components/schemas/Snippet"
        "500":
          description: Server error
          content:
            application/json:
              schema:
                $ref: "#/components/schemas/Error"

components:
  schemas:
    Snippet:
      type: object
      properties:
        id:
          type: integer
        title:
          type: string
        contents:
          type: string
    Error:
      type: object
      properties:
        error:
          type: string

You do not have to cover the full specification. Focus on:

• Paths and operations.
• Response status codes and bodies.
• A shared Error schema that matches what trainees implement in code.