jf

jf is a jo alternative, A small utility to safely format and print JSON objects in the commandline.

However, unlike jo, where you build the JSON object by nesting jo outputs, jf works similar to printf, i.e. it expects the template in YAML format as the first argument, and then the values for the placeholders as subsequent arguments.

INSTALL

Cargo

As a CLI tool

cargo install jf

Or as a library:

cargo add jf

Nixpkgs

nix-env -f https://github.com/NixOS/nixpkgs/tarball/nixos-unstable -iA jf

Binaries

USAGE

jf TEMPLATE [VALUE]... [NAME=VALUE]...

Where TEMPLATE may contain the following placeholders:

• %q quoted and safely escaped JSON string.
• %s JSON values other than string.
• %v the jf version number.
• %% a literal % character.

And [VALUE]... [NAME=VALUE]... are the values for the placeholders.

SYNTAX

• %s, %q posiitonal placeholder.
• %(NAME)s, %(NAME)q named placeholder.
• %(NAME=DEFAULT)s, %(NAME=DEFAULT)q placeholder with default value.
• %(NAME)?s, %(NAME)?q placeholder with optional value.
• %*s, %*q expand positional values as array items.
• %**s, %**q expand positional values as key value pairs.
• %(NAME)*s, %(NAME)*q expand named values as array items.
• %(NAME)**s, %(NAME)**q expand named values as key value pairs.

RULES

• Pass values for positional placeholders in the same order as in the template.
• Pass values for named placeholders using NAME=VALUE syntax.
• Pass values for named array items using NAME=ITEM_N syntax.
• Pass values for named key value pairs using NAME=KEY_N NAME=VALUE_N syntax.
• Optional placeholders default to empty string, which is considered as null.
• Do not declare or pass positional placeholders or values after named ones.
• Expandable positional placeholder should be the last placeholder in a template.

EXAMPLES

  jf %s 1
  # 1

  jf %q 1
  # "1"

  jf [%*s] 1 2 3
  # [1,2,3]

  jf {%**q} one 1 two 2 three 3
  # {"one":"1","two":"2","three":"3"}

  jf "{%q: %(value=default)q, %(bar)**q}" foo value=bar bar=biz bar=baz
  # {"foo":"bar","biz":"baz"}

  jf "{str_or_bool: %(str)?q %(bool)?s, optional: %(optional)?q}" str=true
  # {"str_or_bool":"true","optional":null}

  jf '{1: %s, two: %q, 3: %(3)s, four: %(four=4)q, "%%": %(pct)q}' 1 2 3=3 pct=100%
  # {"1":1,"two":"2","3":3,"four":"4","%":"100%"}

Rust Library

let json = match jf::format(["%q", "JSON Formatted"].map(Into::into)) {
    Ok(value) => value,
    Err(jf::Error::Usage) => {
        bail!("usage: mytool: TEMPLATE [VALUE]... [NAME=VALUE]...")
    }
    Err(jf::Error::Jf(e)) => bail!("mytool: {e}"),
    Err(jf::Error::Json(e)) => bail!("mytool: json: {e}"),
    Err(jf::Error::Yaml(e)) => bail!("mytool: yaml: {e}"),
};