Allow for value to be absent

[adam-vessey]

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https://github.com/Islandora/documentation/issues/2338

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[xurizaemon]

I do not think the change here is correct. \Drupal\islandora\IslandoraUtils::getTermForUri accepts a string per its phpdoc comment, so should not be passed NULL. It doesn't yet have a type declaration on the function argument but may in future.

Regardless, it doesn't make sense to pass NULL to an entityquery (which getTermForURI() will run) to obtain a NULL, that just moves the issue up the chain.

I propose this instead: https://github.com/Islandora/islandora/pull/1048

Not yet tested, but will be able to in a few hours.

[adam-vessey]

@xurizaemon: I'm not seeing where in my code it would be possible for NULL to be passed to IslandoraUtils::getTermForUri()? NULL would be false-y, so it would just memoize and return NULL?

-      $this->structuredTextTerm = $this->utils->getTermForUri($this->options['structured_text_term_uri']);
+      $uri = $this->options['structured_text_term_uri'] ?? NULL;
+      $this->structuredTextTerm = $uri ? $this->utils->getTermForUri($uri) : NULL;

If it's not in the ->options array, $uri would be NULL, if $uri is NULL (or otherwise false-y), it would assign NULL directly ->structuredTextTerm, which already nullable, as the return from ::getTermFormUri() is nullable.

[xurizaemon]

You're right, I'd misread that on my mobile. Apologies and carry on! I will test your fix in a few hours, since I can repro this.

[xurizaemon]

Tested locally, this works perfectly well and as @adam-vessey indicated above. Thanks!