Support a "merge-into-parent" mechanism?

[natevw]

Hello again! I wanted to touch base regarding a feature idea I had for my similar project: natevw/putdoc#9

To summarize my notes there, I'm wondering if you would also like to support a feature that will merge fields from certain JSON file(s) into their parent object? So that way one can set multiple fields in a top-level document using one JSON file [or possibly multiple, see below].

How it might look:

merge_example/
    _id			('example')
    _data.json		('{"type":"container", "name": "My Container", "owner":"me"}')
    _attachments
        file1.jpg
        file2.pdf
        [etc…]

Creates a document:

`{
  "_id":"example",
  "type":"container",
  "name": "My Container",
  "owner":"me",
  "_attachments": {/* … */}
}

It should be a relatively easy add into putdoc at least technically, but if you had interest too I wanted to collaborate on some of the design decisions:

1. How to trigger it? My basic idea so far is by a special file name (like we have with _attachments and _docs folders) in the example above it's _merge or maybe e.g. _fields/_data/…. The actual file 99% of the time would have a JSON extension but I suppose could theoretically be a nested document [not sure the use case but keep things consistent…] or possibly some other extension that is used for serializing an object (think YAML/XML but to be clear I have no plans to support those in putdoc). I implemented this via the _data option, for better or worse.
2. Is it simple and worthwhile enough to support multiple such files e.g. _merge.one.json _merge.two.json and _merge.json would all three have their fields merged into their context. I also implemented this. I left the merge order unspecified; for now conflicting (i.e. duplicate) keys are discouraged and should not be expected to yield stable results.
3. Any other feedback?

Thanks for your time!

[natevw]

Also pinging @benoitc @iblis17 as relatively recent contributors to couchapp/erica. I don't want to file so many issues in those projects yet, but would appreciate any input you have in the meantime.

[natevw]

This is now implemented in putdoc@3.1.0.

If there's interest, it would be good to get this supported across other utilities as a standard feature! For now I included a compatibility warning in my documentation for it.