PythonrequestsCSVJSONAdvanced~7hPart 6 of 6

Python Reach

Data you did not make

Everything your programs have used so far, you wrote. This is the part where it arrives from a file somebody else exported and a service that owes you nothing: read the documentation, ask for exactly what you need, check it before you trust it, and keep working when the answer never comes.

Start this project See the modules

Modules: 7
Drills: 15
Build steps: 10
Time: ~7h

Walk out with

A weekly forecast report, built from a messy locations file and a live service, that still produces a useful answer while three separate things go wrong.

What you'll do

The file you were handed

Convert it, reject what will not, and say why.

Down into the document

Walk a nested response and find what is missing.

Design the request

A parameter table, a requirement, and no finished URL.

Survive the outside world

Bound the wait, name the failure, answer anyway.

The pitch

What you practise, and what you leave with

A weekly forecast report from a messy locations file and a live service, surviving three deliberate failures without a traceback.

You will practise

Say how many rows survive conversion
Predict a response before calling
Decide if a retry is safe, and what it costs
Write the line from memory, at speed

Afterwards you can

Design a request from documentation
Validate data before trusting it
Bound every call your program makes
Produce an answer when things fail

Modules

7 modules, 39 items

Lessons explain one idea. Drills repeat it until it sticks. Build steps make something that exists afterwards.

1
The file you were handed
~55 min
A file that looks fine and is not, and a policy for the rows that are not.
- LessonThe file hands you strings8 min
- LessonA policy for the rows that fail6 min
- DrillHow many rows survive12 min
- DrillWhich rule rejects this row11 min
- Build stepSplit the good from the bad18 min
2
Down into the document
~51 min
Walk a nested response, and tell missing from null from empty.
- LessonWhat the document parsed into7 min
- LessonArrays joined by position only6 min
- DrillWhat is at this path12 min
- DrillMissing, null, or empty12 min
- Build stepFlatten it into records14 min
3
The call and the answer
~1h
One request, end to end, and the two successes that are not the same.
- LessonParameters are data, not text7 min
- LessonRead the envelope first7 min
- Build stepMake the call yourself14 min
- LessonTwo successes that are not6 min
- LessonThree questions, in order6 min
- DrillWhat the response asks for12 min
- DrillDecoded, or actually answered11 min
- DrillSpell the line that reaches out14 min
4
Read the docs, get the data
~1h
A requirement, a parameter table, and no finished URL anywhere.
- LessonFrom a requirement to a request7 min
- LessonPredict before you press send5 min
- DrillWhich request answers this12 min
- DrillPredict the response shape12 min
- Build stepDesign the request yourself16 min
- DrillHow many requests is that12 min
5
Assume it lies
~54 min
The response parsed. Now find out whether any of it can be used.
- LessonCheck it at the boundary8 min
- LessonWhat comes out the far side7 min
- DrillHow many records pass12 min
- DrillWrite the rejection11 min
- Build stepTurn a batch into records16 min
6
When it doesn't answer
~1h
Bound the wait, name the failure, and decide whether to ask again.
- LessonBound how long you will wait7 min
- LessonRetrying, and what it costs6 min
- DrillName the failure12 min
- DrillIs it safe to send again12 min
- DrillWhat the retry budget costs12 min
- Build stepProvoke three failures16 min
7
The build
~1h
A messy file, an address, no labels, and three things that go wrong.
- Build stepPlan it before you write it12 min
- Build stepFetch it once, keep it18 min
- Build stepTransform with the wire unplugged16 min
- Build stepMake it survive three failures20 min