Converting a YAML file to Python JSON object

Question

How can I load a YAML file and convert it to a Python JSON object?

My YAML file looks like this:

Section:
    heading: Heading 1
    font: 
        name: Times New Roman
        size: 22
        color_theme: ACCENT_2

SubSection:
    heading: Heading 3
    font:
        name: Times New Roman
        size: 15
        color_theme: ACCENT_2
Paragraph:
    font:
        name: Times New Roman
        size: 11
        color_theme: ACCENT_2
Table:
    style: MediumGrid3-Accent2

Solution 1

you can use PyYAML

pip install PyYAML

And in the ipython console:

In [1]: import yaml

In [2]: document = """Section:
   ...:     heading: Heading 1
   ...:     font: 
   ...:         name: Times New Roman
   ...:         size: 22
   ...:         color_theme: ACCENT_2
   ...: 
   ...: SubSection:
   ...:     heading: Heading 3
   ...:     font:
   ...:         name: Times New Roman
   ...:         size: 15
   ...:         color_theme: ACCENT_2
   ...: Paragraph:
   ...:     font:
   ...:         name: Times New Roman
   ...:         size: 11
   ...:         color_theme: ACCENT_2
   ...: Table:
   ...:     style: MediumGrid3-Accent2"""
   ...:     

In [3]: yaml.load(document)
Out[3]: 
{'Paragraph': {'font': {'color_theme': 'ACCENT_2',
   'name': 'Times New Roman',
   'size': 11}},
 'Section': {'font': {'color_theme': 'ACCENT_2',
   'name': 'Times New Roman',
   'size': 22},
  'heading': 'Heading 1'},
 'SubSection': {'font': {'color_theme': 'ACCENT_2',
   'name': 'Times New Roman',
   'size': 15},
  'heading': 'Heading 3'},
 'Table': {'style': 'MediumGrid3-Accent2'}}

Solution 2

The PyYAML library is intended for this purpose

pip install pyyaml

import yaml
import json
with open("example.yaml", 'r') as yaml_in, open("example.json", "w") as json_out:
    yaml_object = yaml.safe_load(yaml_in) # yaml_object will be a list or a dict
    json.dump(yaml_object, json_out)

Notes: PyYAML only supports the pre-2009, YAML 1.1 specification.
ruamel.yaml is an option if YAML 1.2 is required.

pip install ruamel.yaml

Solution 3

There is no such thing as a Python JSON object. JSON is a language independent file format that finds its roots in JavaScript, and is supported by many languages.

If your YAML document adheres to the old 1.1 standard, i.e. pre-2009, you can use PyYAML as suggested by some of the other answers.

If it uses the newer YAML 1.2 specification, which made YAML into a superset of JSON, you should use ruamel.yaml (disclaimer: I am the author of that package, which is a fork of PyYAML).

import ruamel.yaml
import json

in_file = 'input.yaml'
out_file = 'output.json'

yaml = ruamel.yaml.YAML(typ='safe')
with open(in_file) as fpi:
    data = yaml.load(fpi)
with open(out_file, 'w') as fpo:
    json.dump(data, fpo, indent=2)

which generates output.json:

{
  "Section": {
    "heading": "Heading 1",
    "font": {
      "name": "Times New Roman",
      "size": 22,
      "color_theme": "ACCENT_2"
    }
  },
  "SubSection": {
    "heading": "Heading 3",
    "font": {
      "name": "Times New Roman",
      "size": 15,
      "color_theme": "ACCENT_2"
    }
  },
  "Paragraph": {
    "font": {
      "name": "Times New Roman",
      "size": 11,
      "color_theme": "ACCENT_2"
    }
  },
  "Table": {
    "style": "MediumGrid3-Accent2"
  }
}

ruamel.yaml, apart from supporting YAML 1.2, has many PyYAML bugs fixed. You should also note that PyYAML's load() is also documented to be unsafe, if you don't have full control over the input at all times. PyYAML also loads scalar numbers 021 as integer 17 instead of 21 and converts scalar strings like on, yes, off to boolean values (resp. True, True and False).

Solution 4

In python3 you can use pyyaml.

$ pip3 install pyyaml

Then you load your yaml file and dump it into json:

import yaml, json

with open('./file.yaml') as f:
    print(json.dumps(yaml.load(f)))

Output:

{"Section": null, "heading": "Heading 1", "font": {"name": "Times New Roman", "size": 22, "color_theme": "ACCENT_2"}, "SubSection": {"heading": "Heading 3", "font": {"name": "Times New Roman", "size": 15, "color_theme": "ACCENT_2"}}, "Paragraph": {"font": {"name": "Times New Roman", "size": 11, "color_theme": "ACCENT_2"}}, "Table": {"style": "MediumGrid3-Accent2"}}

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