350-401 Question #443: Real Exam Question with Answer & Explanation

Question

Which line must be added in the Python function to return the JSON object {"cat_9k": "FXS1932Q2SE")?

Options

• Areturn (json.dumps({d['hostname']: d['serialNumber'] for d in json.loads(test_json)['response']}))
• Breturn (json.dumps({for d in json.loads(test_json)['response']: d['hostname']: d['serialNumber']}))
• Creturn (json.loads({d['hostname']: d['serialNumber'] for d in json.dumps(test_json)['response'}))
• Dreturn (json.loads({for d in json.dumps(test_json)['response']: d['hostname']: d['serialNumber']}))

Explanation

To transform a JSON string into a specific JSON object, the Python function must parse the input, extract the required key-value pairs using a dictionary comprehension, and then serialize the resulting dictionary back to a JSON string.

Common mistakes.

• B. This choice contains a syntax error in the dictionary comprehension; the key-value pair must precede the for loop, i.e., {{key: value for item in iterable}}.
• C. This choice incorrectly uses json.dumps(test_json) (attempting to serialize an already serialized string) and then json.loads() at the end, which would parse a JSON string, not serialize a Python dictionary to JSON.
• D. This choice combines a syntax error in the dictionary comprehension (like B) with the incorrect use of json.loads() for the final output (like C).

Concept tested. Python JSON parsing and dictionary comprehension

Reference. https://docs.python.org/3/library/json.html

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