jsonfmt 0.2.6

A simple tool for formatting JSON object.

JSON Formatter

jsonfmt is a powerful tool for pretty-printing, querying and conversion JSON documents.

It is as powerful as jq, but easier to use.

Features

• 1. Pretty print JSON document.
  • Syntax hight and indenation.
  • Read JSON from pipeline.
• 2. Features for handling large JSON document.
  • View a large JSON with pager-mode.
  • Show the overview of a large JSON.
  • Copy the result to clipboard.
• 3. Minimize the JSON document.
• 4. Pick out parts of a large JSON via JMESPath or JSONPath.
  • JMESPath examples
  • JSONPath examples
  • Query for TOML and YAML
• 5. Convert formats between JSON, TOML and YAML.
  • JSON to TOML and YAML
  • TOML to JSON and YAML
  • YAML to JSON and TOML
• 6. Modify some values in the input data.
  • Add items
  • Modify items
  • Pop items
• 7. Output to file.

Install

$ pip install jsonfmt

Usage

$ jsonfmt [options] [files ...]

• Positional arguments:

  • files: the files that will be processed

• Options:

  • -h, --help: show this help message and exit
  • -c: suppress all whitespace separation
  • -C: copy the result to clipboard
  • -e: escape non-ASCII characters
  • -f {json,toml,yaml}: the format to output (default: same as input)
  • -i {0-8,t}: number of spaces for indentation (default: 2)
  • -o: show data structure overview
  • -O: overwrite the formated text to original file
  • -l {jmespath,jsonpath}: the language for querying (default: jmespath)
  • -p QUERYPATH: the path for querying
  • -s: sort keys of objects on output
  • --set 'foo.k1=v1;k2[i]=v2': set the keys to values (seperated by ;)
  • --pop 'k1;foo.k2;k3[i]': pop the specified keys (seperated by ;)
  • -v: show the version

Example

There are some test data in folder test:

test/
|- example.json
|- example.toml
|- example.yaml

1. Pretty print JSON document.

Syntax hight and indenation.

In the Python, there is a built-in tool for format JSON document: python -m json.tool. But its feature is too simple. So jsonfmt extends its capabilities, such as highlight, pager, overview, etc.

By default, indentation is 2 spaces. You can specify it with option -i. The number of spaces allowed is between 0 and 8. Set it to t if you want to use tab for indentation.

The -s option is used to sort the output of dictionaries alphabetically by key.

If there are some non-ASCII characters in the JSON document, you can use -e to eascape them.

$ jsonfmt -s -i 4 test/example.json

Output:

{
    "actions": [
        {
            "calorie": 294.9,
            "date": "2021-03-02",
            "name": "eat"
        },
        {
            "calorie": -375,
            "date": "2023-04-27",
            "name": "sport"
        }
    ],
    "age": 23,
    "gender": "纯爷们",
    "money": 3.1415926,
    "name": "Bob"
}

Read JSON from pipeline.

Sometimes the JSON you want to process comes from other commands. Just use | to read it from pipeline.

$ cat test/example.json | jsonfmt -i 4

2. Features for handling large JSON document.

View a large JSON with pager-mode.

The pager-mode is similar to the command more.

jsonfmt will automatically present the result in pager-mode when the JSON document is too large to overflow the window display area.

The key-binding of the pager-mode is same as command more:

key	description
j	forward by line
k	backward by line
f	forward by page
ctrl+f	forward by page
b	backward by page
ctrl+b	backward by page
g	go to the top of the page
G	go to the bottom
/	search mode
q	quit pager-mode

There is a big JSON from GitHub, you can paste this command into terminal to try the pager-mode:

curl -s 'https://api.github.com/repos/seamile/jsonfmt/commits?per_page=10' | jsonfmt

Show the overview of a large JSON.

Sometimes we just want to see the overview and don't care about the details of the JSON document. In this case the -o option can be used.

It will clear sublist of the JSON and modify strings to '...' in the overview.

If the root node of the JSON document is a list, only the first child element will be reserved in the overview.

$ jsonfmt -o test/test.json

Output:

{
    "actions": [],
    "age": 23,
    "gender": "...",
    "money": 3.1415926,
    "name": "..."
}

Copy the result to clipboard.

If you want to copy the result into a file and the output of JSON is more than one page in the terminal, it's going to be hard to do.

At this time, you can specify the -C option to copy the result to the clipboard automatically.

$ jsonfmt -C test/example.json

# Output
jsonfmt: result copied to clipboard.

Once you've done the above, you can then use ctrl+v or cmd+v to paste the result anywhere on your computer.

Note these:

• When you specify the -C option, any output destination other than the clipboard will be ignored.
• When you process multiple files, only the last result will be preserved in the clipboard.

3. Minimize the JSON document.

The -c option used to suppress all whitespace and newlines to compact the JSON document into a single line.

$ echo '{
    "name": "alex",
    "age": 21,
    "items": [
        "pen",
        "phone"
    ]
}' | jsonfmt -c

Output:

{"age":21,"items":["pen","phone"],"name":"alex"}

4. Pick out parts of a large JSON via JMESPath or JSONPath.

Unlike from jq's private solution, jsonfmt uses both JMESPath and JSONPath as its query language.

Among the many JSON query languages, JMESPath is the most popular one (compared here). It is more general than jq, and more intuitive and powerful than JSONPath. So I prefer to use it.

Like the XPath for xml, JMESPath can elegantly extract parts of a given JSON document with simple syntax. The official tutorial of JMESPath is here.

JMESPath examples

• pick out the first actions in example.json

  $ jsonfmt -p 'actions[0]' test/example.json
  

  Output:

  {
      "calorie": 294.9,
      "date": "2021-03-02",
      "name": "eat"
  }
  

• Filter all items in actions with calorie > 0.

  $ jsonfmt -p 'actions[?calorie>`0`]' test/example.json
  

  Output:

  [
      {
          "calorie": 294.9,
          "date": "2021-03-02",
          "name": "eat"
      }
  ]
  

• Show all the keys and actions' length.

  $ jsonfmt -p '{all_keys:keys(@), actions_len:length(actions)}' test/example.json
  

  Output:

  {
      "all_keys": [
          "actions",
          "age",
          "gender",
          "money",
          "name"
  ],
      "actions_len": 2
  }
  

• Sort actions by calorie and redefine a dict.

  $ jsonfmt -p 'sort_by(actions, &calorie)[].{name: name, calorie:calorie}' test/example.json
  

  Output:

  [
      {
          "name": "sport",
          "calorie": -375
      },
      {
          "name": "eat",
          "calorie": 294.9
      }
  ]
  

More examples of JMESPath.

JSONPath examples

The syntax of JSONPath is very similar to that of JMESPath. Everything that JSONPath can do JMESPath can also do, except using relative path querying. So JSONPath can be used as a supplementary query method of JMESPath.

• Filter all name fields by relative path:

  # use `-l` to specify the query language of JSON
  $ jsonfmt.py -l jsonpath -p '$..name' test/example.json
  

  Output:

  [
      "Bob",
      "eat",
      "sport"
  ]
  

Query for TOML and YAML

Amazingly, you can do all of the above with TOML and YAML in the same way, and convert the result format arbitrarily. It is even possible to process all three formats simultaneously in a single command.

• Read the data from toml file, and convert the result to yaml

  $ jsonfmt -p '{all_keys:keys(@), actions_len:length(actions)}' test/example.toml -f yaml
  

  Output:

  all_keys:
  - age
  - gender
  - money
  - name
  - actions
  actions_len: 2
  

• Handle three formats simultaneously

  $ jsonfmt.py -p 'actions[0]' test/example.json test/example.toml test/example.yaml
  

  Output:

  {
      "calorie": 294.9,
      "date": "2021-03-02",
      "name": "eat"
  }
  
  calorie = 294.9
  date = "2021-03-02"
  name = "eat"
  
  calorie: 294.9
  date: '2021-03-02'
  name: eat
  

5. Convert formats between JSON, TOML and YAML.

The jsonfmt can recognize any format of JSON, TOML and YAML from files or stdin. Either formats can be converted to the other by specifying the "-f" option.

Note that:

The `null` value is invalid in TOML. Therefore, any null values from JSON or YAML will be removed when converting to TOML.

JSON to TOML and YAML

$ jsonfmt test/example.json -f toml

Output:

age = 23
gender = "纯爷们"
money = 3.1415926
name = "Bob"
[[actions]]
calorie = 294.9
date = "2021-03-02"
name = "eat"

[[actions]]
calorie = -375
date = "2023-04-27"
name = "sport"

$ jsonfmt test/example.json -f yaml

Output:

actions:
- calorie: 294.9
  date: '2021-03-02'
  name: eat
- calorie: -375
  date: '2023-04-27'
  name: sport
age: 23
gender: 纯爷们
money: 3.1415926
name: Bob

TOML to JSON and YAML

# toml to json
$ jsonfmt test/example.toml -f json
# toml to yaml
$ jsonfmt test/example.toml -f yaml

YAML to JSON and TOML

# yaml to json
$ jsonfmt test/example.yaml -f json

# yaml to toml
$ jsonfmt test/example.yaml -f toml

6. Modify some values in the input data.

Use the --set and --pop options when you want to change something in the input documents.

The format is --set 'key=value'. When you need to modify multiple values ​​you can use ; to separate: --set 'k1=v1;k2=v2'. If the key-value pair dose not exist, it will be added.

For the items in list, use key[i] or key.i to specify. If the index is greater than or equal to the number of elements, the value will be appended.

Add items

# add `country` key and append one item for `actions`
$ jsonfmt --set 'country=China; actions[2]={"name": "drink"}' test/example.json

Output:

{
    "actions": [
        {
            "calorie": 294.9,
            "date": "2021-03-02",
            "name": "eat"
        },
        {
            "calorie": -375,
            "date": "2023-04-27",
            "name": "sport"
        },
        {
            "name": "drink"
        }
    ],
    "age": 23,
    "country": "China",
    "gender": "纯爷们",
    "money": 3.1415926,
    "name": "Bob"
}

Modify items

# modify money and actions[1]["name"]
$ jsonfmt --set 'money=1000; actions[1].name=swim' test/example.json

Output:

{
    "actions": [
        {
            "calorie": 294.9,
            "date": "2021-03-02",
            "name": "eat"
        },
        {
            "calorie": -375,
            "date": "2023-04-27",
            "name": "swim"
        }
    ],
    "age": 23,
    "gender": "纯爷们",
    "money": 1000,
    "name": "Bob"
}

Pop items

# pop `gender` and actions[1]
$ jsonfmt --pop 'gender; actions[1]' test/example.json

Output:

{
    "actions": [
        {
            "calorie": 294.9,
            "date": "2021-03-02",
            "name": "eat"
        }
    ],
    "age": 23,
    "money": 3.1415926,
    "name": "Bob"
}

Of course you can use --set and --pop together.

jsonfmt --set 'skills=["Django","Flask"];money=1000' --pop 'gender;actions[1]' test/example.json

Note, however, that the above command will not modify the original JSON file. If you want to do this, read below please.

7. Output to file.

• use the -O parameter to overwrite the file with the result.

  This option will be forced to close when -o is specified

  $ jsonfmt --set 'name=Alex' -O test/example.json
  

• write the result to a new file (use symbol >).

  $ jsonfmt test/example.json > formatted.json