Serializing and deserializing JSON in Python - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to convert a Python dictionary to a JSON string.

Python

import json

data = {"name": "Alice", "age": 30}
json_string = json.[1](data)
print(json_string)

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

Aloads

Bdumps

Cload

Ddump

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'dump' instead of 'dumps' which writes to a file instead of returning a string.

Using 'load' or 'loads' which are for reading JSON, not writing.

The json.dumps() function converts a Python object into a JSON string.

2fill in blank

medium

Complete the code to convert a JSON string back to a Python dictionary.

Python

import json

json_string = '{"name": "Bob", "age": 25}'
data = json.[1](json_string)
print(data)

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

Aload

Bdumps

Cloads

Ddump

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'load' which expects a file object, not a string.

Using 'dump' or 'dumps' which are for writing JSON, not reading.

The json.loads() function parses a JSON string and returns a Python object.

3fill in blank

hard

Fix the error in the code to correctly write a Python dictionary to a JSON file.

Python

import json

data = {"city": "Paris", "population": 2148327}
with open('data.json', 'w') as file:
    json.[1](data, file)

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

Adump

Bloads

Cdumps

Dload

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'dumps' which returns a string instead of writing to a file.

Using 'loads' or 'load' which are for reading JSON.

The json.dump() function writes a Python object as JSON into a file.

4fill in blank

hard

Fill both blanks to deserialize JSON from a file and print the Python object.

Python

import json

with open('info.json', 'r') as [1]:
    data = json.[2]([1])
print(data)

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

Afile

Bloads

Cload

Df

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'loads' which expects a string, not a file object.

Using a different variable name inside the block than the one used in 'with open'.

Open the file with a variable name (e.g., 'f') and use json.load() to read JSON from the file object.

5fill in blank

hard

Fill all three blanks to serialize a Python dictionary with indentation and sort keys.

Python

import json

person = {"name": "Eve", "age": 28, "city": "Berlin"}
json_string = json.[1](person, indent=[2], sort_keys=[3])
print(json_string)

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

Adump

Bdumps

CTrue

D4

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'dump' which writes to a file instead of returning a string.

Passing indentation as a string instead of a number.

Setting sort_keys to a string instead of a boolean.

Use json.dumps() to convert to a JSON string with indentation (4 spaces) and keys sorted alphabetically (sort_keys=True).

Practice

1. What does the json.dumps() function do in Python?

easy

A. Reads JSON data from a file

B. Converts Python data into a JSON formatted string

C. Converts JSON string back to Python data

D. Writes Python data directly to a file

Solution

1. Step 1: Understand the purpose of json.dumps()

   This function takes Python objects like dictionaries or lists and turns them into a JSON string.

2. Step 2: Differentiate from other JSON functions

   json.loads() converts JSON strings back to Python objects, while dumps() does the opposite.

3. Final Answer:

   Converts Python data into a JSON formatted string -> Option B

4. Quick Check:

   Serialize = Python to JSON string [OK]

Hint: Remember: dumps() means dump Python to JSON string [OK]

Common Mistakes:

• Confusing dumps() with loads()
• Thinking dumps() writes to a file
• Assuming dumps() reads JSON data

2. Which of the following is the correct syntax to deserialize a JSON string json_str into a Python object?

easy

A. json.load(json_str)

B. json.dumps(json_str)

C. json.loads(json_str)

D. json.deserialize(json_str)

Solution

1. Step 1: Identify the function to convert JSON string to Python

   The correct function is json.loads(), which takes a JSON string and returns Python data.

2. Step 2: Check other options for correctness

   json.dumps() serializes Python to JSON string, json.load() reads JSON from a file object, and json.deserialize() does not exist.

3. Final Answer:

   json.loads(json_str) -> Option C

4. Quick Check:

   loads() = JSON string to Python [OK]

Hint: Use loads() to load JSON string into Python [OK]

Common Mistakes:

• Using dumps() instead of loads()
• Confusing load() with loads()
• Using a non-existent deserialize() function

3. What will be the output of the following code?

import json
py_data = {'name': 'Alice', 'age': 30}
json_str = json.dumps(py_data)
print(type(json_str))

medium

A. <class 'dict'>

B. TypeError

C. <class 'list'>

D. <class 'str'>

Solution

1. Step 1: Understand what json.dumps() returns

   The json.dumps() function converts Python data into a JSON string, so the result is a string type.

2. Step 2: Check the printed type

   The type(json_str) will be <class 'str'> because json_str holds a JSON string.

3. Final Answer:

   <class 'str'> -> Option D

4. Quick Check:

   dumps() output type = str [OK]

Hint: dumps() returns a string, so type is str [OK]

Common Mistakes:

• Thinking dumps() returns a dict
• Confusing dumps() with loads()
• Expecting a list type output

4. The following code raises an error. What is the mistake?

import json
json_str = '{"name": "Bob", "age": 25}'
py_data = json.load(json_str)
print(py_data)

medium

A. json.load() expects a file object, not a string

B. json_str is not a valid JSON string

C. json.loads() should be replaced with json.dumps()

D. Missing import statement for json module

Solution

1. Step 1: Understand the difference between json.load() and json.loads()

   json.load() reads JSON data from a file-like object, not from a string.

2. Step 2: Identify correct function for string input

   To convert a JSON string to Python data, use json.loads() instead of json.load().

3. Final Answer:

   json.load() expects a file object, not a string -> Option A

4. Quick Check:

   load() = file, loads() = string [OK]

Hint: Use loads() for strings, load() for files [OK]

Common Mistakes:

• Using load() on a string instead of loads()
• Assuming json_str is invalid JSON
• Confusing dumps() and loads()

5. You have a Python list data = [{'id': 1}, {'id': 2}, {'id': 3}]. You want to serialize it to JSON but only include dictionaries where id is greater than 1. Which code correctly does this?

hard

A. json.dumps([item for item in data if item['id'] > 1])

B. json.dumps(data.filter(lambda x: x['id'] > 1))

C. json.dumps(filter(lambda x: x['id'] > 1, data))

D. json.dumps([item for item in data if item.id > 1])

Solution

1. Step 1: Filter list with list comprehension

   Use a list comprehension to select dictionaries where id is greater than 1: [item for item in data if item['id'] > 1].

2. Step 2: Serialize filtered list to JSON string

   Pass the filtered list to json.dumps() to get the JSON string.

3. Final Answer:

   json.dumps([item for item in data if item['id'] > 1]) -> Option A

4. Quick Check:

   Filter with list comprehension, then dumps() [OK]

Hint: Filter with list comprehension before dumps() [OK]

Common Mistakes:

• Using filter() without converting to list
• Trying to access dict keys with dot notation
• Using filter() result directly without list()