Schema and validating

Configcrunch can be used to validate documents. Configcrunch validates documents against a schema. Documents are not validated on load, a special method has to be called instead.

To validate documents, schema is used. For more examples and a full documentation please have a look at the schema documentation.

Let’s say we have the following document:

# fixtures/simple_example.yml
example:
  this: document can contain anything
  int: 12
  map:
    key: value
  list:
    - 1
    - two

To add a schema, we define the schema method of the document class. In this example all fields shown are optional, except for this:

from schema import Schema, SchemaError, Optional
from configcrunch import YamlConfigDocument

class Example(YamlConfigDocument):
    @classmethod
    def header(cls) -> str:
        return "example"

    @classmethod
    def schema(cls) -> Schema:
        return Schema({
            'this': str,
            Optional('int'): int,
            Optional('map'): dict,
            Optional('list'): list
        })

    @classmethod
    def subdocuments(cls):
        return []

You can then use the validate method on documents. On valid documents it returns True and doesn’t raise an error:

>>> document = Example.from_yaml('fixtures/simple_example.yml')
>>> print(document.validate())
True

If you have an invalid document, like the one below, you will get a Schema error detailing the issue.

# fixtures/invalid.yml
example:
  this: 123

>>> document = Example.from_yaml('fixtures/invalid.yml')
>>> try:
...   document.validate()
... except SchemaError as err:
...   print(err)
Key 'this' error:
123 should be instance of 'str'