Snail when editing non-numeric characters on shipping method fees

[filipefurtad0]

Description

In all things similar to #6942, but concerning shipping method fees.

Updating a shipping method can cause a server error when entering invalid values.

Expected Behavior

Invalid values should not be allowed or there should be a proper error message.

Actual Behaviour

It shows the snail.

Steps to Reproduce

1. Edit a shipping method.
2. Select the "per item" calculator.
3. Enter '20.0' with the single quotes as fee amount.
4. Click Update.

Animated Gif/Screenshot

Workaround

Severity

bug-s1: a critical feature is broken: checkout, payments, signup, login
bug-s2: a non-critical feature is broken, no workaround
bug-s3: a feature is broken but there is a workaround
bug-s4: it's annoying, but you can use it
bug-s5: we can live with it, only a few users impacted

https://github.com/openfoodfoundation/openfoodnetwork/wiki/Bug-severity

Your Environment

• Version used: v4.1.2
• Browser name and version: Firefox 92
• Operating System and version (desktop or mobile): Ubuntu 20.04

Possible Fix

The only figures that should be allowed are:

• numbers 0123456789
• decimal point .
• negative sign -

The error message should read:
Invalid input. Please use only numbers. For example: 10, 5.5, -20

See PR which introduces a fix for a similar issue, regarding transaction fees.

[drummer83]

I am afraid we need to reopen this one because not all cases have been covered. There are still some snails.

Summary

Payment methods are covered in #7841 and have been fixed in #8204, only weight calculator is still triggering the snail.
Shipping methods are covered in #8249 and have been addressed in #8312, but incomplete - should be reopened.
Enterprise fees are covered in #8250 and have been addressed in #8308, but incomplete - should be reopened.

Things left to do in this issue

This is the current status of the calculators:

• flat percent --> snail
• flat rate (per order) --> OK
• flexible rate --> snail
• flat rate (per item) --> OK
• price sack --> snail
• weight (per kg or lb) --> probably snail - I didn't want to try due to Shipping fees: Can't change from weight calculator (error 500/snail) #6300

Steps to Reproduce
As an Admin:

• edit a shipping method
• on the calculator section choose one of the calculators marked with "snail" above
• click update
• type in an invalid value (e.g. some text or numbers with comma as separator)
• click update --> snail

[vsmay98]

Hello @filipefurtad0 @drummer83
Can I work on this issue?

[drummer83]

Yes, of course, @vsmay98!
I have assigned it to you, please go ahead!

Looking forward to another contribution of yours! 😊