How can a Cerberus dependency refer to the box above in the document?

Question

I am trying to create a schema for documents that have dependencies that reference the fields above in the document. For instance:

document = {
    'packages': {
        'some-package': {'version': 1}
    },
    'build-steps': {
        'needs-some-package': {'foo': 'bar'},
        'other-thing': {'funky': 'stuff'}
    }
}

What I'm facing right now is the forced dependency between build-steps.needs-some-package and package.some-package. Whenever assembly steps contain "needs-some-package", packages should contain "some-package".

When "needs-some-package" is not, "some-package" is not required. Therefore, this document must also be verified.

other_document = {
    'packages': {
        'other-package': {'version': 1}
    },
    'build-steps': {
        'other-thing': {'funky': 'stuff'}
    }
}

A dependency scheme in what seems like a suitable place,

schema = {
    'packages': {
        'type': 'dict',
        'valueschema': {
            'type': 'dict'
        }
    },
    'build-steps': {
        'type': 'dict',
        'schema': {
            'needs-some-package': {
                'type': 'dict',
                'dependencies': 'packages.some-package'
            },
            'other-thing': {
                'type': 'dict'
            }
        }
    }
}

, , Cerberus "" " ". ? - ?

Answer 1

1.0.2:

. , ^. (^^) , ^ .

:

import cerberus

schema = {
    'packages': {
        'type': 'dict',
        'valueschema': {
            'type': 'dict'
        }
    },
    'build-steps': {
        'type': 'dict',
        'schema': {
            'needs-some-package': {
                'type': 'dict',
                'dependencies': '^packages.some-package'
            },
            'other-thing': {
                'type': 'dict'
            }
        }
    }
}

document = {
    'packages': {
        'some-package': {'version': 1}
    },
    'build-steps': {
        'needs-some-package': {'foo': 'bar'},
        'other-thing': {'funky': 'stuff'}
    }
}

validator = cerberus.Validator(schema)
print(validator.validate(document))