Refactoring: Handling of ERP errors

[ThomasRossmeisl]

Description

Currently ERP errors are captured by the -OnConnect script and checked by the Edit-ResponseWithErrorMessage function after ERP communication. This approach has the following issues:

• Edit-ResponseWithErrorMessage returns different data type depending on input AND external server result. This makes it impossible to know the result of the function and caused nullpointer exceptions in multiple projects as the developer forgot to handle all possible return values. Also it makes conditions harder to read and write as multiple different results need to be handled.
• There are no separate cases for error and "new" case. This makes the code hard to understand and causes entities to be marked as 'new' incorrectly

Remarks

• Checking the response should return the same datatype at all times. In PowerShell this can be achieved by using a hashtable or introducing a new class that is used as a struct. The hashtable is more reliable as classes need special care as they aren't loaded by import-module

Related Issues

• Requires #211

[TollJulian]

I worked on this issue on the Sotawall project and could resolve the following tasks:

Edit-ResponseWithErrorMessage returns different data type depending on input AND external server result. This makes it impossible to know the result of the function and caused nullpointer exceptions in multiple projects as the developer forgot to handle all possible return values. Also it makes conditions harder to read and write as multiple different results need to be handled.

Now the Edit-ResponseWithErrorMessage returns always a hashtable with this structure: $result = @{Entity = (the ERP object the check was made for); ErrorMessage = (the powerGate error)}

The functions using Edit-ResponseWithErrorMessage do not indicate in their name that they check the erp response. This exacerbates the issue with the mixed return values, but also makes the code harder to understand in general as the names indicate an erp object is returned at all times

The names of all the functions using Edit-ResponseWithErrorMessage end with WithPGError. To evidence their return type, I renamed the variables who call those functions. (e.G. $erpSomethingHashtable = doSomethingWithPGError(...)

There are no separate cases for error and "new" case. This makes the code hard to understand and causes entities to be marked as 'new' incorrectly

The hashtable structure allows to differenciate clearly between Error, New and Existant:

• Error: result.Entity = $null; result.ErrorMessage = (Error)
• New: result.Entity = $null; result.ErrorMessage = $null
• Existant: result.Entity = (entity); result.ErrorMessage = $null

The function calls override the same variables multiple times which makes it hard to tell what value is currently passed to what function and leads to more programming errors

renamed some variables to avoid this

this is already open: The OnConnect code is complicated and hard to understand. A lot of code is required to use it which also might introduce new errors

The solution is pushed into branch issue_#208

[TollJulian]

This has to been tested on the Sotawall Project

[ThomasRossmeisl]

https://github.com/coolOrangeLabs/powerGateTemplate/commit/8c8b9cc22b7116cc67b215be65af0a24eae7db67