TIMX 655 - handle deletes for researchdatabases - #276
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Why these changes are being introduced: With the proposed introduction of a new ReseaarchDatabases transformation class that may also use the LibGuides API, it makes sense to have it refactored out of libguides.py. How this addresses that need: The LibGuidesAPIClient is refactored to helpers.py. Side effects of this change: * None Relevant ticket(s): * https://mitlibraries.atlassian.net/browse/TIMX-655
Why these changes are being introduced: It turns out that the Springshare OAI endpoint that we harvest AZ items (research databases) has *never* produced deletes. Without those deleted records / tombstones in OAI, we were not successfully removing records from TIMDEX. Transmogrifier is currently the place in the TIMDEX ETL ecosystem where records are first written to the dataset, and most commonly, if they are records to index or delete. There may come a time when explicit pre-transform work is performed to establish source records in the TIMDEX dataset, then we transform them, but Transmogrifier has historically been responsible for that double duty and continues to be at this time. Ultimately, we need to identify AZ items that are no longer publicly available and establish `action=delete` records in the TIMDEX dataset to have them removed. The OAI harvester is less per-source opinionated than Transmogrifier, making it a poor choice for this. How this addresses that need: A new ResearchDatabases transformer class has been created. Formerly, the TIMDEX source `researchdatabases` used the Springshare transformer class as a naive OAIDC XML transformation. This new class changes nothing about the metadata transformation, but allows for a place to identify records that were formerly indexed in TIMDEX but are no longer publicly accessible. There is precedence here in the libguides source, which also performs some additional work via the Springshare API. With that scaffolding already present, it was a relatively simple addition to have researchdatabases do a bit of extra work beyond the OAI XML records provided. The ResearchDatabases transformer does something unique: while yielding the OAI XML records provided by the harvester like normal, it also queries the Springshare API and identifies records we've seen before but are no longer public. For these a *synthetic* OAI XML record is injected into the records yielded by this class for transformation. Those are handled by pre-existing logic and ultimately get written to the TIMDEX dataset with `action=delete`. Side effects of this change: * The researchdatabase source now requires the Springshare API credentials that formerly only the libguides source required. * If AZ items are deleted or hidden, they should get removed from TIMDEX now. Relevant ticket(s): * https://mitlibraries.atlassian.net/browse/TIMX-655
Why these changes are being introduced: There were some edge cases with the reliance on the env var LAST_AZ_IDENTIFIERS_PATH for identifying deletes in researchdatabases: - env var is not set - file does not exist - desire to NOT check for deletes How this addresses that need: Now, ResearchDatabases transformer only queries the Springshare API if the env var LAST_AZ_IDENTIFIERS_PATH is set. If the file does not exist it will create it. This keeps the source fully backwards compatible, but when the env var is set, it is utilized and deletes are detected. Side effects of this change: * researchdatabases source remains fully backwards compatbile until env var LAST_AZ_IDENTIFIERS_PATH is set. Relevant ticket(s): * https://mitlibraries.atlassian.net/browse/TIMX-655
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Will keep the branch, but pivoting on approach. This was writing a text file to S3 with a list of identifiers. Instead, we can query the TIMDEX dataset directly for what it thinks are current records, then ensure that matches Springshare's OAI/API results. All without juggling text files. |
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