Accessing JSON data in Flask - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to get JSON data from a Flask request.

Flask

data = request.[1]()

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

Aget_json

Bjson

Cjsonify

Dget_data

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'jsonify' which is for creating JSON responses, not reading JSON from requests.

Using 'json' which is a module, not a method on request.

Using 'get_data' which returns raw data, not parsed JSON.

The get_json() method extracts JSON data from the request body in Flask.

2fill in blank

medium

Complete the code to access the value of the 'name' key from JSON data.

Flask

name = data[1]"name"]

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

A(

B.

C[

D{

Attempts:

3 left

💡 Hint

Common Mistakes

Using dot notation which does not work on dictionaries.

Using parentheses which are for function calls.

Using curly braces which define dictionaries, not access keys.

JSON data parsed into a Python dictionary is accessed using square brackets [] with the key as a string.

3fill in blank

hard

Fix the error in accessing nested JSON data for key 'address' then 'city'.

Flask

city = data["address"][1]"city"]

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

A[

B.

C(

D{

Attempts:

3 left

💡 Hint

Common Mistakes

Using dot notation for nested keys.

Using parentheses which cause syntax errors.

Using curly braces which are for dictionary literals.

To access nested dictionary keys, use square brackets for each key step.

4fill in blank

hard

Fill both blanks to safely get the 'age' key from JSON data with a default of 0.

Flask

age = data.[1]("age", [2])

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

Aget

B0

CNone

Dpop

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'pop' which removes the key from the dictionary.

Using 'None' as default which is not the intended default here.

Using dot notation without a method.

The get method retrieves a key's value or returns the default if the key is missing.

5fill in blank

hard

Fill all three blanks to create a Flask route that accepts JSON POST requests and returns the 'status' key.

Flask

from flask import Flask, request, jsonify

app = Flask(__name__)

@app.route('/status', methods=[[1]])
def get_status():
    data = request.[2]()
    status = data.get([3], 'unknown')
    return jsonify({'status': status})

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

A'POST'

Bget_json

C'status'

D'GET'

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'GET' method which does not send JSON in the body.

Using 'jsonify' instead of 'get_json' to read data.

Using wrong key name or missing quotes.

The route must accept POST requests, use get_json() to get JSON data, and access the 'status' key.

Practice

1. In Flask, which method is used to access JSON data sent in a POST request?

easy

A. request.json()

B. request.json_data()

C. request.get_data()

D. request.get_json()

Solution

1. Step 1: Identify the Flask method for JSON data

   Flask provides request.get_json() to parse JSON body data safely.

2. Step 2: Confirm method usage

   This method returns a Python dictionary from the JSON sent in the request.

3. Final Answer:

   request.get_json() -> Option D

4. Quick Check:

   Use request.get_json() to access JSON data [OK]

Hint: Use request.get_json() to get JSON data in Flask [OK]

Common Mistakes:

• Using request.json() which does not exist
• Using request.get_data() which returns raw bytes
• Using request.json_data() which is not a Flask method

2. Which of the following is the correct way to safely access the value of the key 'name' from JSON data in Flask?

easy

A. data['name']

B. data.get('name')

C. data.name

D. data['Name']

Solution

1. Step 1: Understand dictionary access in Python

   JSON data parsed by request.get_json() is a Python dictionary.

2. Step 2: Choose safe key access method

   Using data.get('name') safely returns the value or None if key missing, avoiding errors.

3. Final Answer:

   data.get('name') -> Option B

4. Quick Check:

   Use dict.get() to safely access JSON keys [OK]

Hint: Use data.get('key') to avoid KeyError if missing [OK]

Common Mistakes:

• Using data['Name'] with wrong case
• Using data.name which is invalid for dict
• Using data['name'] without checking key existence

3. Given the Flask route code:

from flask import Flask, request
app = Flask(__name__)

@app.route('/data', methods=['POST'])
def data():
    json_data = request.get_json()
    return json_data.get('age', 'No age provided')

What will be the response if the JSON sent is {"name": "Alice"}?

medium

A. "No age provided"

B. KeyError

C. None

D. "Alice"

Solution

1. Step 1: Analyze JSON input and key access

   The JSON sent has no 'age' key, only 'name'.

2. Step 2: Understand get() default behavior

   Using json_data.get('age', 'No age provided') returns the default string when 'age' is missing.

3. Final Answer:

   "No age provided" -> Option A

4. Quick Check:

   Missing key returns default value in get() [OK]

Hint: get() returns default if key missing, no error [OK]

Common Mistakes:

• Expecting KeyError instead of default value
• Confusing returned value with another key
• Assuming None is returned without default

4. What is wrong with this Flask code snippet for accessing JSON data?

@app.route('/submit', methods=['POST'])
def submit():
    data = request.get_json
    return data['email']

medium

A. Missing import of request

B. Using data['email'] without checking if key exists

C. request.get_json is missing parentheses

D. Route method should be GET instead of POST

Solution

1. Step 1: Check method call syntax

   request.get_json is a method and must be called with parentheses: request.get_json().

2. Step 2: Identify impact of missing parentheses

   Without parentheses, data is a method reference, not the JSON dict, causing errors on key access.

3. Final Answer:

   request.get_json is missing parentheses -> Option C

4. Quick Check:

   Always call get_json() with () to get JSON data [OK]

Hint: Call get_json() with parentheses to get data [OK]

Common Mistakes:

• Forgetting parentheses after get_json
• Not checking if key exists before access
• Assuming GET method for JSON POST route

5. You want to safely extract the 'username' and 'email' from JSON data in a Flask route, providing default values if keys are missing. Which code snippet correctly does this?

hard

A. data = request.get_json()
username = data.get('username', 'guest')
email = data.get('email', '[e-mail]')

B. data = request.get_json()
username = data['username']
email = data['email']

C. data = request.get_json
username = data.get('username', 'guest')
email = data.get('email', '[e-mail]')

D. data = request.get_json()
username = data.get('username') or 'guest'
email = data['email']

Solution

1. Step 1: Use get_json() correctly

   Call request.get_json() with parentheses to get JSON data as a dict.

2. Step 2: Use dict.get() with defaults for safe access

   Use data.get('key', default) to provide fallback values if keys are missing.

3. Final Answer:

   data = request.get_json() username = data.get('username', 'guest') email = data.get('email', '[e-mail]') -> Option A

4. Quick Check:

   Use get_json() and dict.get() with defaults for safe JSON access [OK]

Hint: Use data.get('key', default) after get_json() call [OK]

Common Mistakes:

• Not calling get_json() as a method
• Accessing keys directly without defaults
• Mixing method call and attribute access