How do I parse a yaml string with python?

Question

I see an API and many examples on how to parse a yaml file but what about a string?

FYI YAML is not safe. It is susceptible to vulnerabilities that allows the user to execute code on your servers https://www.youtube.com/watch?v=LrW-HSHP0ws — AlanSTACK, May 05 '18 at 05:59
@AlanSTACK thanks for the heads up, I was looking for a quick way to try some things, in particular how multi-line strings are parsed in yaml. — gae123, May 05 '18 at 06:02
@KlausD. this remark would have been more appropriate if there was something obvious to try. `yaml.load/safe_load` is polymorphic in what it accepts, but if all the examples show files, leaves one to look for something else to handle strings, as json does it with `load`/`loads`. Hard to try using a function that doesn't exist and there's nothing wrong with ... just asking a question. — JL Peyret, Aug 12 '20 at 07:03

score 74 · Accepted Answer · edited Apr 13 '23 at 00:59

74

Here is the best way I have seen so far demonstrated with an example:

import yaml

dct = yaml.safe_load('''
name: John
age: 30
automobiles:
- brand: Honda
  type: Odyssey
  year: 2018
- brand: Toyota
  type: Sienna
  year: 2015
''')

assert dct['name'] == 'John'
assert dct['age'] == 30
assert len(dct["automobiles"]) == 2
assert dct["automobiles"][0]["brand"] == "Honda"
assert dct["automobiles"][1]["year"] == 2015

edited Apr 13 '23 at 00:59

Mateen Ulhaq

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answered May 05 '18 at 05:40

gae123

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When I use this method, the type of `dct` is still string – Nikhil Talreja Sep 04 '19 at 11:19
8

you should use `yaml.safe_load` for untrusted inputs – Tomas Tomecek Jan 03 '20 at 14:23
1

if you need to install the library, be aware that it is `pip install pyyaml` but `import yaml` – Johannes Feb 11 '21 at 12:45

score 12 · Answer 2 · answered Jan 03 '20 at 14:26

12

You don't need to wrap the string in StringIO, the safe_load method accepts strings:

In [1]: yaml.safe_load("{1: 2}")           
Out[1]: {1: 2}

answered Jan 03 '20 at 14:26

Tomas Tomecek

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How do I parse a yaml string with python?

2 Answers2

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