Flattening a JSON Object Using Recursion in Python

As part of our back-to-basic series Liz breaks down a real coding interview challenge she completed which landed her a job. This week’s problem uses recursion to flatten a JSON object in python.

The Challenge:
Write a function to flatten a JSON object with nested keys into a single level

Video Overview:
0:59 The problem
1:45 Example walkthrough
3:10 Coding a solution
18:30 Walking through with a debugger
23:03 Closing

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[samanthalee]

This is the clearest coding tutorial I've ever seen in my life. Liz you are awesome. Very high quality step by step break down of the problem and solution.

[HakeemLawrence]

Liz, I love you for this. You saved my life. I will watch all of your other videos. Thank you so much! I really appreciate it!

[kjuarez]

One helluva good explanation! Please keep making videos

[m.e.k]

Here is the code that will work on all data structures

def run_on_dict(data):
for key, value in data.items():
if isinstance(value, dict):
run_on_dict(value)
elif isinstance(value, list):
for element in value:
if isinstance(element, (dict, list)):
run_on_dict(element)
else:
print(f"{key}: {element}")
else:
print(f"{key}: {value}")

[thisoldproperty]

Very clear. Very concise. First time I've come across your videos. How you have more of these. Thank you.

[thndesmondsaid]

I think this solution may break down in the list section if the elements within the list are dicts? Need to test it though to be sure.

[idanqwe]

Hey, what if we want to get back from flatten to json object?

[Troglodyte]

That jacket of yours, that logo is cool! :)

[gboyegaabidoye]

great explanation, thank you. what if you want the output in a tabular form

[rahimskmd]

How do I take one key value pair based on some condition, like from ur example I want city in Canada that starts with M

[madmonk]

Nice tutorial, thanks!
Have you got any tips if I want to only output specific keys in the json object? (Parameterised as a list)

Eg json object:
obj = {'key1' :
{'key2':
{'key3': 'value1',
'key4': 'value2'
}
}
}

When caling the flatten function:
flatten_json( obj, ["key1.key2", "key3.key4"])

Desired output:
{
"key1.key2": "value1",
"key3.key5": "value3"
}

[riz]

where is the code? Please provide the link so that it can be test.