PyYAML dump format

Question

I know there are a few questions about this on SO, but I couldn\'t find what I was looking for.

I\'m using pyyaml to read (.load()) a .yml

Answer 1

In my case, I want " if value contains a { or a }, otherwise nothing. For example:

 en:
   key1: value is 1
   key2: 'value is {1}'

To perform that, copy function represent_str() from file representer.py in module PyYaml and use another style if string contains { or a }:

def represent_str(self, data):
    tag = None
    style = None
    # Add these two lines:
    if '{' in data or '}' in data:
        style = '"'
    try:
        data = unicode(data, 'ascii')
        tag = u'tag:yaml.org,2002:str'
    except UnicodeDecodeError:
        try:
            data = unicode(data, 'utf-8')
            tag = u'tag:yaml.org,2002:str'
        except UnicodeDecodeError:
            data = data.encode('base64')
            tag = u'tag:yaml.org,2002:binary'
            style = '|'
    return self.represent_scalar(tag, data, style=style)

To use it in your code:

import yaml

def represent_str(self, data):
  ...

yaml.add_representer(str, represent_str)

In this case, no diffences between keys and values and that's enough for me. If you want a different style for keys and values, perform the same thing with function represent_mapping