Save a document as JSON

Write the document in a tab to a file as JSON, whatever format the tab is read from, print a file's tree as JSON from the shell, or copy one value of the document as JSON.

Whatever format a tab is read from, its document is a tree of JSON's values. aless writes that tree out as JSON. The example opens the tutorial's file, bookshelf-openapi.yaml. That file is an OpenAPI document in YAML.

Write the whole document #

To write the document to a file, type :w, a space, and a filename, such as :w bookshelf.json, and then press Enter. aless says Wrote bookshelf.json on the status line.

Whichever node has the focus, aless writes the whole document, so you don't need to move the focus before you type :w. aless pretty-prints the JSON with two spaces a level. The JSON's keys keep the order they have in the source.

aless resolves a relative filename from the directory it started in. :w refuses a file that exists, so that a mistyped name doesn't overwrite an existing file. :w! writes over the file.

Line mode shows the same JSON in the viewer, so you can read the JSON before you write it. In line mode, the tree keeps its folds. m switches line mode on and off.

What the JSON holds #

The file that :w writes holds the tree the viewer shows, not the text of the source:

Comments aren't in the tree, so they aren't in the file.
A number keeps its spelling where JSON spells it the same way, so 1.0 stays 1.0. A spelling that JSON lacks gives the value it stands for, so 0x1F becomes 31. For more information, see Formats.
A format whose tree has a shape of its own keeps that shape in the file. aless writes an XML file as element records, a Markdown file as its syntax tree, and a CSV file as an array of records. For more information, see Formats.

Print the JSON from the shell #

To get the same JSON in a script, pass --print-json and the file. aless prints the tree as JSON on standard output, and exits. The viewer doesn't start, so no terminal is needed, and the JSON can go to a pipe or a file. Here the start of the OpenAPI document's JSON goes to head:

$ aless --print-json bookshelf-openapi.yaml | head -5
{
  "openapi": "3.0.0",
  "info": {
    "title": "Bookshelf demo API",
    "version": "1.0.0",

The JSON is the same JSON that :w writes. -k, --grammar, and the other input options work as they do for the viewer. The viewer's own options, such as --depth, make no difference. A - in place of the file reads standard input, as JSON unless -k names another format:

$ printf 'name: aless\ntags: [tree, json]\n' | aless -k yaml --print-json -
{
  "name": "aless",
  "tags": [
    "tree",
    "json"
  ]
}

When the file can't be read or doesn't parse, aless prints the report on standard error, prints nothing on standard output, and exits with the status 1. A script can test for that status:

$ aless --print-json broken.json; echo "exit status $?"
[tabnas/unexpected]: unexpected character(s): ]
  --> broken.json:3:36
  1 | {
  2 |   "title": "A Book of Examples",
  3 |   "tags": ["examples", "reference",]
                                         ^ unexpected character(s): ]
  4 | }
  5 |

  The character(s) ] do not match any rule alternative active at
  this position.

  --internal: tag=-; rule=val~o; token=#CS; plugins=--
exit status 1

For more information about the report, see Find out why a file does not parse.

Copy one value instead #

yy copies the focused value as indented JSON. yv copies the same value as JSON on one line. When the focus is on a container, the value copied is the whole container, so yy on one path of an API description copies every operation under that path. For more information, see Copy a value or its path.