How to use $ref to reference a path from another OpenAPI file?

Question

Here it says I could refer to the definition in another file for an individual path, but the example seems to refer to a whole file, instead of a single path definition under the paths object. How to assign an individual path in another file's paths object?

For example, I have Anotherfile.yaml that contains the /a/b path:

paths:
  /a/b:
    post:

In another file, I use $ref to reference the /a/b path as follows:

paths:
  /c/d:
    $ref: 'Anotherfile.yaml#/paths/a/b'

but this gives an error:

Could not find paths/a/b in contents of ./Anotherfile.yaml

Answer 1

When referencing paths, you need to escape the path name by replacing / with ~1, so that /a/b becomes ~1a~1b. Note that you escape just the path name and not the #/paths/ prefix.

$ref: 'Anotherfile.yaml#/paths/~1a~1b'