Fix civiimport crash on unmapped fields, remove overzealous cleanup, add api to help debug & test

[eileenmcnaughton]

Overview

Fix civiimport crash on unmapped fields

Before

When I production tested the civivimport extension I hit a crash because on unmapped fields the name is unset. I think I hit this in production but not in prior testing because I was using an existing mapping - which I wasn't doing in my last tests in my dev tests.

After

Crash fixed

In prod testing I quickly felt that adding the validate and import api to help diagnose problems was really helpful. Since that part only affects the exensions, which is still alpha, I added them into this too.

Technical Details

Unmapped fields coming in via qf have the name property set, but equal to ''. In earlier cuts it was do_not_import. This still checks for do_not_import but uses an empty check rather than a comparison on '' - I could ensure it is always passed at the js layer - but that feels more fragile & I can't easily add a test

Comments

I also removed a table clean up that was part of the old form layer - but the form layer is not doing it's own thing so it's just plain risky now & may be why I have seen some odd behaviours around table delete

[civibot]

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[eileenmcnaughton]

@colemanw can you merge this -still focussed on the extension - which is alpha / disabled in the rc but trying to keep stuff together

[eileenmcnaughton]

oh & also - it fixes a bug & a dodgey-ness