Support for custom additional metadata

[matmair]

Hi! We use this library within the context of a more complex Django application that requires some additional environment settings to be similar between backup and restore.
It would be great if we could define additional custom metadata to be saved (maybe via a string pointing to a function that returns the data) and a function that might raise an error if the loaded metadata might cause issues doing a restore.

I would be happy to work on this and submit a patch if this is something that would be accepted

[Archmonger]

Sure - we can add support for custom metadata. In your use case, are you imagining a scenario where you get/set this metadata within the CLI? Or would it be programmatic (within Python)?

[matmair]

I would do it programmatic to ensure the metadata reflects the actual production environment (think things like specific Postgres extensions, version number of a specific model, release date of the running software version)

[Archmonger]

Sounds good. Feel free to open and PR with an API that would help you. We can discuss/tweak the API within the PR, if needed.

[Archmonger]

Resolved in #663