It'd be nice to also resolve templates from files

[hairyhenderson]

Let's start with JSON support (because encoding/json). I figure usage like this would be useful:

data.json

{
  "name": {
    "first": "Joe"
  }
}

in.txt

Hello {{.data.name.first}}!

(where data comes from the name of the file)

$ gomplate -f data.json < in.txt
Hello Joe!

[drewmacinnis]

Yeah, a -f would be handy.

[hairyhenderson]

Something that might be a bit simpler to implement, and would probably flow better with the rest of the built-in functions is:

Hello {{ (jsonfile "data.json").name.first }}

$ gomplate -d data.json < in.txt
Hello Joe!

[hairyhenderson]

...although if I'm taking a path or filename as the argument to jsonfile, then I don't need to pass it on the commandline...

Conversely, forcing a file to be named a specific way may not be a good plan either. Maybe something like:

Hello {{ (jsonfile "data").name.first }}

$ gomplate -d data.json < in.txt
Hello Joe!

Where "data" is resolved because the file is named data.json. I could support mappings with = like:

$ gomplate -d data=myotherfilename.json < in.txt
Hello Joe!

It'd be interesting to also support other data sources from URLs, so to treat the -d argument like: alias=URL, or:

$ gomplate -d data=https://some.url/where/i/can/find/data.json < in.txt
Hello Joe!

This implies a few things:

1. jsonfile is a bad name - it should be something more generic like datasource
2. in the absence of =, the argument is assumed to be a file in the cwd, and the alias is set to the file name (sans extension)
3. paths (i.e. anything with a directory name in it, not just the filename) and URLs would require the alias

[drmdrew]

I like the "data source alias" idea. Perhaps always use uri style? Like file:// https://?

[hairyhenderson]

yeah - well data.json is technically a valid relative URL, so if we always use the cwd as the base file:// url, there shouldn't be any special-casing needed.

I was also thinking I could support lots of different formats this way (eventually!) like yaml or toml or even XML, detecting by Content-Type with a fallback to file extension...