Multi-line in a sequence in YAML

Question

I would like to have multiple lines in a sequence in YAML. This is how I do it, but I have issues with parsing it in python:

Element: |
   - multiple lines
     come here

Doing it this way, when I parse it with Python, I still see the - in the parsed data. It seems that YAML does not understand this is a list.

Answer 1

Your input is not a list, YAML only knows about mappings (constructed as a Python dict and sequences (constructed as a Python list).

Normally - is the block sequence entry indicator, But since you start a block style literal on the first line as the value for the key Element, because of the |, everything following it that is indented is part of this scalar (constructed as a Python string).

What you want to do is bring the indicator outside of the literal scalar:

Element: 
- |
  multiple lines
  come here

If you load that in Python in a variable data then data['Element'][0] will be the string 'multiple lines\ncome here\n'. That is: every newline in your literal scalar will be a newline in your string, and there will be a single final newline on that string independent of how many empty lines follow (this is clipping). If you want the end to have no newline, then use |- (stripping), and if you want all newlines until outdenting then use |+ (keeping). Those additions to the | are called chomping indicators.

If you have the above in a file called input.yaml:

import sys
from pathlib import Path
import ruamel.yaml

input = Path('input.yaml')

yaml = ruamel.yaml.YAML(typ='safe')
data = yaml.load(input)
print(f'{data["Element"][0]!r}')  # print the representation, so you can see where the newlines are

which gives:

'multiple lines\ncome here\n'

Answer 2

Use this syntax (for the yaml Python package, at least)

stuff:
  - 'this is a multiline
  string'

In other words quote the string and unindent its continuation.