Manage Quotes in YAML Files Using Python

In this tutorial, you’ll learn various methods to handle quotes in YAML using Python.

We’ll cover different quoting methods, adding and removing quotes, escaping special characters using quotes, and preserving existing quote styles.

 

 

Quoting methods in YAML

Single quotes vs. double quotes

In YAML, you can enclose strings using single quotes (' ') or double quotes (" ").

Both quoting styles have their purposes, and understanding the difference helps you decide which to use in various situations.

You can parse YAML content with PyYAML to see how quotes affect string values:

import yaml
yaml_content = '''
name: "Ahmed"
greeting: 'Hello, world!'
quote_in_double: "He said, 'YAML is easy.'"
quote_in_single: 'He said, "YAML is easy."'
'''
data = yaml.safe_load(yaml_content)
print(data)

Output:

{'name': 'Ahmed', 'greeting': 'Hello, world!', 'quote_in_double': "He said, 'YAML is easy.'", 'quote_in_single': 'He said, "YAML is easy."'}

The quotes in YAML ensure that strings containing special characters or spaces are correctly interpreted.

Single quotes allow double quotes inside the string and vice versa.

When to use each type

Use single quotes when your string contains double quotes or special characters you want to interpret literally.

Use double quotes when you need to include escape sequences like \n or when your string contains single quotes.

For example, if your string includes a single quote, you can use double quotes to enclose it without escaping:

import yaml
yaml_content = '''
message: "It's a sunny day."
'''
data = yaml.safe_load(yaml_content)
print(data)

Output:

{'message': "It's a sunny day."}

 

Add quotes to YAML strings

Forcing quotes on all strings

You can force all strings to be quoted by using the ruamel.yaml library and setting the default_style parameter:

import ruamel.yaml
data = {
    'name': 'Mariam',
    'city': 'Cairo',
    'age': '30'
}
yaml = ruamel.yaml.YAML()
yaml.default_style = '"'
import io
stream = io.StringIO()
yaml.dump(data, stream)
print(stream.getvalue())

Output:

"name": "Mariam"
"city": "Cairo"
"age": "30"

All keys and values are now enclosed in double quotes in the output YAML.

Add quotes to specific values

You can selectively quote specific values by using ruamel.yaml scalar string types.

To add quotes to specific values, wrap them with the appropriate scalar string type such as DoubleQuotedScalarString and SingleQuotedScalarString:

import ruamel.yaml
from ruamel.yaml.scalarstring import DoubleQuotedScalarString, SingleQuotedScalarString
data = {
    'name': DoubleQuotedScalarString('Mariam'),
    'city': SingleQuotedScalarString('Cairo'),
    'age': 30
}
yaml = ruamel.yaml.YAML()
import io
stream = io.StringIO()
yaml.dump(data, stream)
print(stream.getvalue())

Output:

name: "Mariam"
city: 'Cairo'
age: 30

The name value is double-quoted, the city value is single-quoted, and age remains unquoted.

 

Escape quotes within strings

To include quotes within strings, you can escape them or use different quotes:

import ruamel.yaml
from ruamel.yaml.scalarstring import DoubleQuotedScalarString
data = {
    'message': DoubleQuotedScalarString('He said, "It\'s a sunny day."')
}
yaml = ruamel.yaml.YAML()
import io
stream = io.StringIO()
yaml.dump(data, stream)
print(stream.getvalue())

Output:

message: "He said, \"It's a sunny day.\""

The single quote doesn’t need to be escaped within the double-quoted string, but the double quotes inside need to be escaped with a backslash.

Alternatively, you can use single quotes outside:

from ruamel.yaml.scalarstring import SingleQuotedScalarString
data = {
    'message': SingleQuotedScalarString('He said, "It\'s a sunny day."')
}
yaml.dump(data, stream)
print(stream.getvalue())

Output:

message: 'He said, "It''s a sunny day."'

In single-quoted strings, single quotes are escaped by doubling them.

 

Deal with special characters

Colons, question marks, or leading zeros can cause parsing issues if not properly quoted.

You can ensure special characters are handled correctly by quoting the strings:

import ruamel.yaml
from ruamel.yaml.scalarstring import DoubleQuotedScalarString
data = {
    'time': DoubleQuotedScalarString('08:00'),
    'question': DoubleQuotedScalarString('What is your name?'),
    'path': '/usr/bin'
}
yaml = ruamel.yaml.YAML()
import io
stream = io.StringIO()
yaml.dump(data, stream)
print(stream.getvalue())

Output:

time: "08:00"
question: "What is your name?"
path: /usr/bin

The time '08:00' is quoted to prevent it from being interpreted as a timestamp.

The 'question' string is quoted to handle the question mark properly.

The 'path' does not require quoting since it doesn’t contain special characters that affect parsing.

 

Preserve existing quotes

When modifying YAML files, preserving the existing quote styles is important.

The ruamel.yaml library can maintain the original quotes when loading and dumping YAML content by setting preserve_quotes to True:

import ruamel.yaml
yaml = ruamel.yaml.YAML()
yaml.preserve_quotes = True
yaml_content = '''
name: 'Mariam'
city: "Cairo"
message: "She said, 'Welcome!'"
'''
data = yaml.load(yaml_content)
import io
stream = io.StringIO()
yaml.dump(data, stream)
print(stream.getvalue())

Output:

name: 'Mariam'
city: "Cairo"
message: "She said, 'Welcome!'"

 

Remove unnecessary quotes

You can remove quotes by setting default_style to None and ensure the values are of appropriate types:

import ruamel.yaml
data = {
    'name': 'Mariam',
    'city': 'Cairo',
    'age': 30
}
yaml = ruamel.yaml.YAML()
yaml.default_style = None
import io
stream = io.StringIO()
yaml.dump(data, stream)
print(stream.getvalue())

Output:

name: Mariam
city: Cairo
age: 30

With default_style set to None, the dumper does not add quotes unless necessary.