What's the correct way to create a YAML document without a file?

Question

I want to create a YAML file from scratch inside a python program (with PyYAML), to send it inside a HTTP request body. The closest thing I've found in the PyYAML docs is this:

import yaml
document = """
  a: 1
  b:
    c: 3
    d: 4
"""
yaml.load(document)
send_req(document)

However, I find it ugly and not very maintainable, so I would like to be able to do something like this:

document = {'a': 1, 'b': {'c': 3, 'd': 4}}
yaml.load(document)
send_req(document)

So I can modify its structure in a programmatic way, with variables and so.

How can I create a YAML document from a python object structure?

Answer 1

I think what you want is yaml.dump.

document = {'a': 1, 'b': {'c': 3, 'd': 4}}
print(yaml.dump(document))
>>> a: 1
b: {c: 3, d: 4}

For simple Python objects you can even serialize .__dict__ directly:

class MyClass(object):
    def __init__(self, a, b):
        self.a = a
        self.b = b

my_obj = MyClass(1, 2)
print(yaml.dump(my_obj.__dict__))
>>> {a: 1, b: 2}