Global data files priority according to file extensions #794

[gloryofrobots]

This PR resolves #794 and also adds merging of global data from different files with the same base filename into one object

For example if we have files

//_data/data.js
module.exports = {
  key1: "js-val1"
}

// _data/data.json
{
   "key1": "json-val1",
   "key2": "json-val2"
}

resulting data objects will be merged according to extension priority so js will override json

{
  "key1":  "js-val1",
  "key2":  "json-val2"
}

Working on this PR I found that 11tydata.{json|js} files are not supported due to code in TemplateData.getObjectPathForDataFile
I do not know if it is a bug or a normal behavior. To clarify this I created #820

[zachleat]

Please read #820 (comment)

[zachleat]

As stated in #820 I have a few concerns that this will be a breaking change for folks? This might need to roll out in 1.0

[gloryofrobots]

Thanks for the feedback.
This PR doesn't change how TemplateData.getObjectPathForDataFile works. So _data/globalfile.11tydata.json will work as before.
Here I implemented the extension priority (so js will rank higher than json) and data merging according to this priority. Maybe, it will not break existing codebases because most of the projects, probably do not use the same filenames with different extensions for global data. In the current state, such data objects will override each other depending on the glob result order which is very unreliable in any case.

[zachleat]

In the current state, such data objects will override each other depending on the glob result order which is very unreliable in any case.

Agree, yes. Makes good sense. I’ll remove the breaking change tag here.

[zachleat]

Merging, thanks!