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Serialise Customer Summaries to JSON — Python For Entrepreneurs

Day 21 · ~12 min●

Your load_customers_from_csv gives you a clean customer list. How do you currently share the plan summary with your engineering team or a webhook?

After load_customers_from_csv I can load the data. But sharing it — pasting into Slack, sending to a webhook — means I need a string format. JSON is what everything speaks.

json.dumps(data, indent=2) takes any Python dict or list and turns it into a formatted JSON string. Two lines:

python

import json
summary = plan_summary(customers)
output = json.dumps(summary, indent=2)
print(output)

What's indent=2? Can I just use json.dumps(data) without it?

You can — json.dumps(data) produces a compact one-line string. indent=2 adds pretty-printing with two spaces per level. For a Slack message or reading in a terminal, indent=2 is much more readable. Here's the full function:

python

def customers_to_json(customers: list) -> str:
    import json
    summary = plan_summary(customers)
    result = json.dumps(summary, indent=2)
    print(f"JSON length: {len(result)} chars")
    return result

So the output is a JSON string I can paste directly into a Slack webhook body. The whole plan summary — totals, ARPU, every plan — in one call.

Your Slack bot will thank you. json.dumps is the universal handshake between Python and every other system.

I can now load a Stripe CSV, compute the plan summary, and export it as JSON in three function calls. That's a real data pipeline.

json.loads(s) is the reverse — turns a JSON string back into a Python dict. The round-trip is json.loads(json.dumps(data)) == data. Always true for JSON-serialisable values: strings, numbers, bools, lists, dicts, and null.

JSON Serialisation

json.dumps converts Python data to a JSON string. json.loads reverses it.

python

import json
json.dumps({"mrr": 14850.0}, indent=2)  # pretty string
json.loads('{"mrr": 14850.0}')           # back to dict

Serialisable types

Python	JSON
`str`	string
`int` / `float`	number
`bool`	`true` / `false`
`None`	`null`
`list`	array
`dict`	object

Pitfall

datetime, set, and Decimal are NOT serialisable. Convert to string or float before dumping.

Day 21 · ~12 min●

Your load_customers_from_csv gives you a clean customer list. How do you currently share the plan summary with your engineering team or a webhook?

After load_customers_from_csv I can load the data. But sharing it — pasting into Slack, sending to a webhook — means I need a string format. JSON is what everything speaks.

json.dumps(data, indent=2) takes any Python dict or list and turns it into a formatted JSON string. Two lines:

python

import json
summary = plan_summary(customers)
output = json.dumps(summary, indent=2)
print(output)

What's indent=2? Can I just use json.dumps(data) without it?

python

def customers_to_json(customers: list) -> str:
    import json
    summary = plan_summary(customers)
    result = json.dumps(summary, indent=2)
    print(f"JSON length: {len(result)} chars")
    return result

So the output is a JSON string I can paste directly into a Slack webhook body. The whole plan summary — totals, ARPU, every plan — in one call.

Your Slack bot will thank you. json.dumps is the universal handshake between Python and every other system.

I can now load a Stripe CSV, compute the plan summary, and export it as JSON in three function calls. That's a real data pipeline.

JSON Serialisation

json.dumps converts Python data to a JSON string. json.loads reverses it.

python

import json
json.dumps({"mrr": 14850.0}, indent=2)  # pretty string
json.loads('{"mrr": 14850.0}')           # back to dict

Serialisable types

Python	JSON
`str`	string
`int` / `float`	number
`bool`	`true` / `false`
`None`	`null`
`list`	array
`dict`	object

Pitfall

datetime, set, and Decimal are NOT serialisable. Convert to string or float before dumping.

def customers_to_json(customers: list) -> str: import json summary = plan_summary(customers) result = json.dumps(summary, indent=2) print(f"JSON length: {len(result)} chars") return result

JSON Serialisation

json.dumps converts Python data to a JSON string. json.loads reverses it.

python

import json
json.dumps({"mrr": 14850.0}, indent=2)  # pretty string
json.loads('{"mrr": 14850.0}')           # back to dict

Serialisable types

Python	JSON
`str`	string
`int` / `float`	number
`bool`	`true` / `false`
`None`	`null`
`list`	array
`dict`	object

Pitfall

datetime, set, and Decimal are NOT serialisable. Convert to string or float before dumping.

def customers_to_json(customers: list) -> str: import json summary = plan_summary(customers) result = json.dumps(summary, indent=2) print(f"JSON length: {len(result)} chars") return result

JSON Serialisation

json.dumps converts Python data to a JSON string. json.loads reverses it.

python

import json
json.dumps({"mrr": 14850.0}, indent=2)  # pretty string
json.loads('{"mrr": 14850.0}')           # back to dict

Serialisable types

Python	JSON
`str`	string
`int` / `float`	number
`bool`	`true` / `false`
`None`	`null`
`list`	array
`dict`	object

Pitfall

datetime, set, and Decimal are NOT serialisable. Convert to string or float before dumping.