feat(gatsby-plugin-sitemap): handle different query structures and allow custom siteUrl resolution

[moonmeister]

Description

Resolves some of the issues discussed in #20692.

• Previously when querying pages using allSitePage.nodes instead of allSitePage.edges was impossible because the serializer and internal page filter expected the edges object structure.

• Previously you had to set your siteUrl at site.siteMetaData.siteUrl or the default resolver would fail. This seemed pointless when using other methods to resolve siteUrl. You can now define a function that receives the query result as "data", and you can return a string that will be used for siteUrl.

TBD

While this solution works there is a lot of "odd" things i had to do to make it backwards compatible. Specifically when filtering pages I convert the the data structure to an array of pages from either the edges or nodes structure. But it also still assumes use of allSitePage which kinda defeats the point of being able to write a custom query.

Logic has been added to handle both data structures. The absurd part is I have to return that data structure back to its original state to maintain backwards compatibility when handing the data back to the serializer. This applies to siteUrl resolution as well. Even if you write a custom resolver, accessing in in the serializer is still done at site.siteMetaData.siteUrl.

All this could be eliminated and the general api made more flexible and probably simpler, if we are okay with doing a major version bump.

Documentation

//TODO

Related Issues

closes #20692

[pieh]

All this could be eliminated and the general api made more flexible and probably simpler, if we are okay with doing a major version bump.

I think generally we are ok with doing major version bump for plugins (not tied to gatsby core major version bumps) with asterisk that breaking changes make sense and are thought out so we don't have to do another major version bump anytime soon to fixup problems in new API/options design.

In meantime I think we can live with a bit of "absurdity" (as you nicely described it :P)

[moonmeister]

@pieh thanks. I'll finish docs changes this week and we can merge this as is. It sounds like if I felt like doing a more serious rewrite that'd be welcome. ✌️

[pieh]

Let me know if you want code review or should I wait for docs ;)

[moonmeister]

@pieh Got the docs in there. Thanks. I should have time for any needed changes this week.

[laurieontech]

Minor change, but docs look solid to me.

[pieh]

Code looks good, let's get this in. Thanks @moonmeister!

[pieh]

Published [email protected]

[vladar]

Apparently this PR contains some breaking change? #22703