Export class code readability - Reduce passing of variable, define on class

[eileenmcnaughton]

Overview

Code readability refactor towards being able to review & merge fixes to the Export functionality

Before

$contactRelationships passed from pillar to post

After

self::$relationshipTypes used instead

also self::$memberOfHouseholdRelationshipKey & $headOfHouseholdRelationshipKey defined & a function extracted in the test (this is towards adding second test but is added as incomplete at this stage as it passes on local mysql config but not CI config - which is in fact the bug we are working towards addressing)

Technical Details

This is one of series of small refactors aimed at getting the toxic code to a point where I feel comfortable reviewing the proposed changes & bug fix

Comments

@monishdeb

[civibot]

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[eileenmcnaughton]

test this please

[eileenmcnaughton]

@monishdeb this is currently blocking further work on your export fixes

[monishdeb]

@eileenmcnaughton earlier when I included the cleanup changes on my earlier PR #11901 and #11870 during rebase, it breaks the workflow and thus reflected on the added test failure. I need to revert some of the changes but still with no luck :( This is a very complex code and took me days to understand and fix the DB error.
I will first try to correct the errors on those 2 PRs and will review it.

[eileenmcnaughton]

@monishdeb the thing is I pretty much concluded I was not going to be able to review your 2 Prs until we had massively simplified the code - ie. I think about 10 more PRs of this size need to be done & merged before we reach the point where we can take the logic of your PRs & fix the actual thing - I wasn't necessarily trying to keep the specific code changes in your PRs as I did this but to eventually enact the logic.

[jitendrapurohit]

I've reviewed the changes on the export screen and while skimming through the code. +1 for the cleanup 👍

[eileenmcnaughton]

merging based on @jitendrapurohit - thanks!