Feature Request: Publish rich DDI-Codebook metadata via OAI-PMH

Overview of the Feature Request

There are discrepancies between the DDI-Codebook metadata available via the web interface and through OAI-PMH. Specifically, the metadata accessed via OAI-PMH appears less rich.

For example, using the web interface, I can download rich DDI-Codebook metadata for this dataset:
https://dataverse.harvard.edu/dataset.xhtml?persistentId=doi:10.7910/DVN/BT3LXD
Direct download link:
https://dataverse.harvard.edu/api/datasets/export?exporter=ddi&persistentId=doi%3A10.7910/DVN/BT3LXD
This version includes detailed elements such as <fileDscr> and <dataDscr>.

However, when accessing the same dataset via OAI-PMH:
https://dataverse.harvard.edu/oai?verb=GetRecord&identifier=doi:10.7910/DVN/BT3LXD&metadataPrefix=oai_ddi
those elements are missing.

While I can imagine there may be reasons for this difference, I encourage you to look into it and consider providing the richer DDI-Codebook metadata via OAI-PMH—especially since it’s already available through the web interface.

What inspired the request?

In my own research (https://doi.org/10.29173/iq1116, https://doi.org/10.5281/zenodo.15410806) on publication of DDI metadata I found that Dataverse instances are globally a major source for DDI metadata). Because I expect especially fine-grained metadata to be extremely valuable they should be accessible via established protocols.

What existing behavior do you want changed?

Include DDI-Codebook metadata which are already available also in the versions that are provided via OAI-PMH. If still the reduced version should be available, perhaps an extended version can be published using a new metadataPrefix like oai_ddi_extended (or use oai_ddi_bibligraphic and oai_ddi_extendend). An additional OAI-PMH endpoint would perhaps make less sense, because I would not expect, that this additional URL can be published e.g. on re3data.org which serves as a registry of repositories.

Start by comparing the OAI-PMH GetRecord response with metadataPrefix=oai_ddi against the web export at /api/datasets/export?exporter=ddi for the cited dataset. Determine how the existing DDI-Codebook output is produced and define whether richer elements such as and should be added to oai_ddi or exposed through a new metadataPrefix; done means the chosen OAI-PMH response consistently includes the intended metadata.