Allow importing partial backup (fixes #4672)

[Nutomic]

LocalUser::update was throwing an error if there was nothing changed. Not sure why Person::update is working as both queries seem identical.

[dullbananas]

This causes all error types to be ignored. Things like connection problems should not be ignored. Try making it only ignore QueryBuilderError.

[dessalines]

Rather than doing this, check this out from the diesel update docs:

It should be noted that receiving 0 rows from get_result is considered an error condition by default. If you want to get back 0 or 1 row (e.g. have a return type of QueryResult<Option>), then you will need to call .get_result(...).optional().

So I'd recommend doing the same thing I did for inserts, but for all updates: adding .optional() so that we can catch the runtime errors. IMO this should be done for all updates, so we can handle that case.

If you want me to handle this, lmk.

[dullbananas]

That would not hadle the case of all fields in the update form being set to None, which throws QueryBuilderError

[dessalines]

I'm going to open up an issue in diesel for this, bc it needs a similar solution to optional() then, or optional should also handle that case.

[dessalines]

In the meantime, you can do a match on that specific err.kind() https://stackoverflow.com/a/43884600/1655478

[dullbananas]

In this case, it should be Err(Error::QueryBuilderError(_)) =>

[Nutomic]

Fixed now.

[dessalines]

Seems good.