OpenAPI schema customization in FastAPI - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set a custom title for the OpenAPI schema in FastAPI.

FastAPI

from fastapi import FastAPI
app = FastAPI(title=[1])

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

A"My API"

B'My API'

CMy API

Dtitle="My API"

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting to put quotes around the title string.

Passing the title without quotes causing a syntax error.

The title parameter expects a string, so it must be enclosed in quotes.

2fill in blank

medium

Complete the code to add a description to the OpenAPI schema in FastAPI.

FastAPI

app = FastAPI(description=[1])

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

A"API description here"

Bdescription="API description here"

C'API description here'

DAPI description here

Attempts:

3 left

💡 Hint

Common Mistakes

Passing description without quotes causing errors.

Using the parameter name inside the value.

The description must be a string literal, so it needs quotes.

3fill in blank

hard

Fix the error in the code to set the OpenAPI version in FastAPI.

FastAPI

app = FastAPI(openapi_version=[1])

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

A'3.0.0'

B"3.0.0"

C3.0.0

D3.0

Attempts:

3 left

💡 Hint

Common Mistakes

Passing version as a number without quotes.

Using incomplete version strings.

The openapi_version must be a string, so it needs quotes around the version number.

4fill in blank

hard

Fill both blanks to customize the OpenAPI schema with a title and version.

FastAPI

app = FastAPI(title=[1], openapi_version=[2])

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

A"Custom API"

B"2.0.0"

C'2.0.0'

D'Custom API'

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing quotes or missing quotes for either parameter.

Using numbers without quotes for version.

Both title and openapi_version require string values with quotes.

5fill in blank

hard

Fill all three blanks to set title, description, and version in FastAPI OpenAPI schema.

FastAPI

app = FastAPI(title=[1], description=[2], openapi_version=[3])

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

A"My API"

B"This is my API description."

C"3.0.1"

D'3.0.1'

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting quotes on any parameter.

Using single quotes inconsistently.

All three parameters require string values enclosed in quotes.

Practice

1. What is the main purpose of customizing the OpenAPI schema in a FastAPI application?

easy

A. To provide clear API documentation with custom titles, descriptions, and versions

B. To speed up the API response time

C. To change the database connection settings

D. To automatically generate frontend UI components

Solution

1. Step 1: Understand OpenAPI schema role

   The OpenAPI schema defines how the API is documented and described for users and tools.

2. Step 2: Identify customization benefits

   Customizing it lets you add titles, descriptions, versions, and contact info to make docs clearer.

3. Final Answer:

   To provide clear API documentation with custom titles, descriptions, and versions -> Option A

4. Quick Check:

   OpenAPI schema customization = clear docs [OK]

Hint: Think: OpenAPI schema = API documentation details [OK]

Common Mistakes:

• Confusing schema customization with performance tuning
• Thinking it changes database or backend logic
• Assuming it auto-generates frontend code

2. Which of the following is the correct way to set a custom title and version for your FastAPI app's OpenAPI schema?

easy

A. app = FastAPI(schema_title="My API", schema_version="1.0.0")

B. app = FastAPI(openapi_title="My API", openapi_version="1.0.0")

C. app = FastAPI(title="My API", version="1.0.0")

D. app = FastAPI(api_title="My API", api_version="1.0.0")

Solution

1. Step 1: Recall FastAPI app parameters

   FastAPI accepts title and version as direct parameters in its constructor.

2. Step 2: Match correct parameter names

   The correct parameters are exactly title and version, not schema_title or openapi_title.

3. Final Answer:

   app = FastAPI(title="My API", version="1.0.0") -> Option C

4. Quick Check:

   FastAPI(title, version) = correct syntax [OK]

Hint: Use 'title' and 'version' directly in FastAPI() [OK]

Common Mistakes:

• Using incorrect parameter names like openapi_title
• Trying to set schema properties after app creation
• Confusing app config with route decorators

3. Given this FastAPI app code, what will be the OpenAPI docs URL by default?

from fastapi import FastAPI
app = FastAPI(title="Test API")

@app.get("/items/")
async def read_items():
    return [{"item_id": "foo"}]

medium

A. /api-docs

B. /openapi.json

C. /swagger

D. /docs

Solution

1. Step 1: Recall FastAPI default docs path

   FastAPI by default serves Swagger UI at the path /docs.

2. Step 2: Differentiate docs and schema URLs

   /openapi.json is the raw schema JSON, not the interactive docs UI.

3. Final Answer:

   /docs -> Option D

4. Quick Check:

   Default docs URL = /docs [OK]

Hint: Swagger UI docs default path is /docs in FastAPI [OK]

Common Mistakes:

• Confusing /openapi.json with docs UI
• Assuming /swagger or /api-docs are default
• Not knowing FastAPI defaults for docs

4. What is wrong with this FastAPI app code if the goal is to hide the automatic docs UI?

app = FastAPI(docs_url=None)

@app.get("/users")
async def get_users():
    return [{"name": "Alice"}]

medium

A. docs_url should be set to False, not None

B. You must also set redoc_url=None to hide all docs

C. docs_url parameter does not exist in FastAPI

D. docs_url=None is correct and will hide docs UI

Solution

1. Step 1: Understand docs_url and redoc_url

   FastAPI has two docs UIs: Swagger UI at docs_url and ReDoc at redoc_url.

2. Step 2: Check hiding docs UI fully

   Setting docs_url=None hides Swagger UI but ReDoc remains unless redoc_url=None is also set.

3. Final Answer:

   You must also set redoc_url=None to hide all docs -> Option B

4. Quick Check:

   Hide all docs = docs_url=None + redoc_url=None [OK]

Hint: Set both docs_url and redoc_url to None to hide docs [OK]

Common Mistakes:

• Assuming docs_url=None hides all docs
• Using invalid values like False for docs_url
• Not knowing about ReDoc docs URL

5. You want to customize your FastAPI app's OpenAPI schema to include a contact email and license info. Which code snippet correctly achieves this?

hard

A. app = FastAPI(contact={"email": "[e-mail]"}, license_info={"name": "MIT"})

B. app = FastAPI(openapi_info={"contact": {"email": "[e-mail]"}, "license": {"name": "MIT"}})

C. app = FastAPI(openapi_contact={"email": "[e-mail]"}, openapi_license={"name": "MIT"})

D. app = FastAPI(openapi_contact_email="[e-mail]", openapi_license_name="MIT")

Solution

1. Step 1: Recall FastAPI parameters for contact and license

   FastAPI uses contact and license_info parameters to customize OpenAPI schema contact and license sections.

2. Step 2: Match correct parameter names and structure

   contact and license_info expect dictionaries with keys like email and name respectively.

3. Final Answer:

   app = FastAPI(contact={"email": "[e-mail]"}, license_info={"name": "MIT"}) -> Option A

4. Quick Check:

   Use contact and license_info dicts in FastAPI() [OK]

Hint: Use contact and license_info dicts in FastAPI() constructor [OK]

Common Mistakes:

• Using openapi_contact or openapi_license which are invalid
• Trying to nest contact inside openapi_info
• Passing strings instead of dicts for contact/license