How can I include a YAML file inside another?

Question

So I have two YAML files, "A" and "B" and I want the contents of A to be inserted inside B, either spliced into the existing data structure, like an array, or as a child of an element, like the value for a certain hash key.

Is this possible at all? How? If not, any pointers to a normative reference?

Answer 1

No, YAML does not include any kind of "import" or "include" statement.

Answer 2

Your question does not ask for a Python solution, but here is one using PyYAML.

PyYAML allows you to attach custom constructors (such as !include) to the YAML loader. I've included a root directory that can be set so that this solution supports relative and absolute file references.

Class-Based Solution

Here is a class-based solution, that avoids the global root variable of my original response.

See this gist for a similar, more robust Python 3 solution that uses a metaclass to register the custom constructor.

import yaml import os  class Loader(yaml.SafeLoader):      def __init__(self, stream):          self._root = os.path.split(stream.name)[0]          super(Loader, self).__init__(stream)      def include(self, node):          filename = os.path.join(self._root, self.construct_scalar(node))          with open(filename, 'r') as f:             return yaml.load(f, Loader)  Loader.add_constructor('!include', Loader.include) 

An example:

foo.yaml

a: 1 b:     - 1.43     - 543.55 c: !include bar.yaml 

bar.yaml

- 3.6 - [1, 2, 3] 

Now the files can be loaded using:

>>> with open('foo.yaml', 'r') as f: >>>    data = yaml.load(f, Loader) >>> data {'a': 1, 'b': [1.43, 543.55], 'c': [3.6, [1, 2, 3]]}