Remarshal

Convert between CBOR, JSON, MessagePack, TOML, and YAML. When installed, Remarshal provides the command-line command remarshal as well as the short commands {cbor,json,msgpack,toml,yaml}2{cbor,json,msgpack,toml,yaml}. You can use these commands to convert between formats, reformat, and detect errors.

Known limitations and quirks

There are limitations on what data can be converted between what formats.

CBOR, MessagePack, and YAML with binary fields cannot be converted to JSON or TOML. Binary fields can be converted between CBOR, MessagePack, and YAML.
The following date-time value conversions are possible:
- Local dates are converted between CBOR RFC 8943 dates (tag 1004), TOML Local Dates, and YAML timestamps without a time or a time zone.
- Local date-time is converted between TOML Local Date-Time and YAML timestamps without a time zone.
- Date-time with a time zone is converted between CBOR standard date-time strings (tag 0), the MessagePack Timestamp extension type, TOML Offset Date-Times, and YAML timestamps with a time zone.
TOML Local Time cannot be converted to a date-time in another format.
All date-time types can be converted to JSON with the -k/--stringify option, which turns them into strings.
Contrary to the YAML timestamp draft spec, Remarshal converts YAML dates to TOML Local Dates instead of TOML Offset Dates in the UTC time zone. It converts TOML Local Dates to YAML dates.

Installation

You will need Python 3.8 or later. Earlier versions of Python 3 will not work.

The recommended way to run Remarshal is to install the latest release from PyPI with pipx.

pipx install remarshal

Regular installation is not mandatory. The command

pipx run remarshal [arg ...]

will download Remarshal and run it from a temporary location. It will cache the downloaded version for up to 14 days. Remarshal will not be automatically upgraded during this period.

You can also install Remarshal using pip.

python3 -m pip install --user remarshal

It is possible to install the current development version of Remarshal. Prefer releases unless you have a reason to run the development version.

pipx install git+https://github.com/remarshal-project/remarshal

Usage

usage: remarshal [-h] [-v] [-i <input>] [--if {cbor,json,msgpack,toml,yaml}]
                 [--json-indent <n>] [-k] [--max-values <n>] [-o <output>]
                 [--of {cbor,json,msgpack,toml,yaml}] [-s] [--unwrap <key>]
                 [--verbose] [--wrap <key>] [--yaml-indent <n>]
                 [--yaml-style {,',",|,>}] [--yaml-width <n>]
                 [input] [output]

Convert between CBOR, JSON, MessagePack, TOML, and YAML.

positional arguments:
  input                 input file
  output                output file

options:
  -h, --help            show this help message and exit
  -v, --version         show program's version number and exit
  -i <input>, --input <input>
                        input file
  --if {cbor,json,msgpack,toml,yaml}, --input-format
{cbor,json,msgpack,toml,yaml}, -f {cbor,json,msgpack,toml,yaml},
--from {cbor,json,msgpack,toml,yaml}
                        input format
  --json-indent <n>     JSON indentation
  -k, --stringify       turn into strings: boolean and null keys and date-time
                        keys and values for JSON; boolean, date-time, and null
                        keys and null values for TOML
  --max-values <n>      maximum number of values in input data (default
                        1000000, negative for unlimited)
  -o <output>, --output <output>
                        output file
  --of {cbor,json,msgpack,toml,yaml}, --output-format
{cbor,json,msgpack,toml,yaml}, -t {cbor,json,msgpack,toml,yaml},
--to {cbor,json,msgpack,toml,yaml}
                        output format
  -s, --sort-keys       sort JSON and TOML keys instead of preserving key order
  --unwrap <key>        only output the data stored under the given key
  --verbose             print debug information when an error occurs
  --wrap <key>          wrap the data in a map type with the given key
  --yaml-indent <n>     YAML indentation
  --yaml-style {,',",|,>}
                        YAML formatting style
  --yaml-width <n>      YAML line width for long strings

Instead of remarshal with format arguments, you can use a short command {cbor,json,msgpack,toml,yaml}2{cbor,json,msgpack,toml,yaml}. The remarshal command and the short commands exit with status 0 on success, 1 on operational failure, and 2 on failure to parse the command line.

If no input argument input/-i input is given or its value is -, Remarshal reads input data from standard input. Similarly, with no output/-o output or an output argument that is -, Remarshal writes the result to standard output.

Wrappers

The options --wrap and --unwrap are available to solve the problem of converting CBOR, JSON, MessagePack, and YAML data to TOML when the top-level element of the data is not of a dictionary type (i.e., not a map in CBOR and MessagePack, an object in JSON, or an associative array in YAML). You cannot represent such data as TOML directly; the data must be wrapped in a dictionary first. Passing the option --wrap some-key to remarshal or one of its short commands wraps the input data in a "wrapper" dictionary with one key, some-key, with the input data as its value. The option --unwrap some-key does the opposite: it converts to the target format and outputs only the value stored under the key some-key in the top-level dictionary element of the input data; the rest of the input is discarded. If the top-level element is not a dictionary or does not have the key some-key, --unwrap some-key causes an error.

The following shell transcript demonstrates the problem and how --wrap and --unwrap solve it:

$ echo '[{"a":"b"},{"c":[1,2,3]}]' | remarshal --if json --of toml
Error: cannot convert non-dictionary data to TOML; use "--wrap" to wrap it in a dictionary

$ echo '[{"a":"b"},{"c":[1,2,3]}]' \
  | remarshal --if json --of toml --wrap main
[[main]]
a = "b"

[[main]]
c = [1, 2, 3]

$ echo '[{"a":"b"},{"c":[1,2,3]}]' \
  | remarshal --if json --wrap main - test.toml

$ remarshal test.toml --of json
{"main":[{"a":"b"},{"c":[1,2,3]}]}

$ remarshal test.toml --of json --unwrap main
[{"a":"b"},{"c":[1,2,3]}]

Examples

$ remarshal example.toml --of yaml
title: TOML Example
owner:
  name: Tom Preston-Werner
  organization: GitHub
  bio: "GitHub Cofounder & CEO\nLikes tater tots and beer."
  dob: 1979-05-27 07:32:00+00:00
database:
  server: 192.168.1.1
  ports:
  - 8001
  - 8001
  - 8002
  connection_max: 5000
  enabled: true
servers:
  alpha:
    ip: 10.0.0.1
    dc: eqdc10
  beta:
    ip: 10.0.0.2
    dc: eqdc10
    country: 中国
clients:
  data:
  - - gamma
    - delta
  - - 1
    - 2
  hosts:
  - alpha
  - omega
products:
- name: Hammer
  sku: 738594937
- name: Nail
  sku: 284758393
  color: gray

$ curl -f 'https://archive-api.open-meteo.com/v1/era5?latitude=50.43&longitude=30.52&start_date=2014-10-05&end_date=2014-10-05&hourly=temperature_2m' \
  | remarshal --from json --to toml \
  | taplo fmt - \
  ;
latitude = 50.439365
longitude = 30.476192
generationtime_ms = 0.04291534423828125
utc_offset_seconds = 0
timezone = "GMT"
timezone_abbreviation = "GMT"
elevation = 147.0

[hourly_units]
time = "iso8601"
temperature_2m = "°C"

[hourly]
time = [
  "2014-10-05T00:00",
  "2014-10-05T01:00",
  "2014-10-05T02:00",
  "2014-10-05T03:00",
  "2014-10-05T04:00",
  "2014-10-05T05:00",
  "2014-10-05T06:00",
  "2014-10-05T07:00",
  "2014-10-05T08:00",
  "2014-10-05T09:00",
  "2014-10-05T10:00",
  "2014-10-05T11:00",
  "2014-10-05T12:00",
  "2014-10-05T13:00",
  "2014-10-05T14:00",
  "2014-10-05T15:00",
  "2014-10-05T16:00",
  "2014-10-05T17:00",
  "2014-10-05T18:00",
  "2014-10-05T19:00",
  "2014-10-05T20:00",
  "2014-10-05T21:00",
  "2014-10-05T22:00",
  "2014-10-05T23:00",
]
temperature_2m = [
  5.7,
  5.3,
  5.0,
  4.8,
  4.6,
  4.6,
  7.0,
  8.9,
  10.8,
  12.2,
  13.3,
  13.9,
  13.9,
  13.7,
  13.3,
  12.3,
  11.1,
  10.2,
  9.4,
  8.5,
  8.2,
  7.9,
  8.0,
  7.8,
]

(This example uses taplo fmt to reformat the TOML and break up long lines containing the arrays. Remarshal does not limit TOML line length.)

License

MIT. See the file LICENSE.

example.toml from https://github.com/toml-lang/toml. example.json, example.msgpack, example.cbor, example.yml, tests/bin.msgpack, and tests/bin.yml are derived from it.