Package gavo :: Package base :: Module metavalidation

Module metavalidation

Meta information validation.

The idea is that you define certain assertions about the meta information of a given object type. Defined assertions are

MetaExists -- a key is present
MetaIsAtomic -- a key is present and a "leaf", i.e., has a single value
MetaAtomicExistsOnSelf -- a key is present even without meta inheritance, and has a single value

Validators are usually built using model descriptions. These are enumerations of meta keys, separated by commata, with an optional code in parenteses. Whitespace is ignored. Codes allowed in parens are:

empty (default): plain existence
!: atomic existance on self
1: atomic existance

An example for a valid model description: "publisher.name,creator.email(), identifier (!), dateUpdated(1)"

These model descriptions can come in metaModel attributes of structures. If they are, you can use the validateStructure function below to validate an entire structure tree.

Classes
	MetaValidationError
	MetaAssertion An assertion about the meta content of an object.
	MetaExists An assertion that a meta item is present for key in whatever form.
	MetaIsAtomic An assertion that a meta item is present and contains a single value only.
	MetaAtomicExistsOnSelf An assertion that a meta item is present and unique for key on metaCarrier itself.
	MetaValidator A metadata model that can verify objects of compliance.

Functions

parseModel(modelDescr)
returns a MetaValidator for a model description.

source code

validateStructure(aStruct)
does a meta validation for a base.Structure.

source code

Variables
	__package__ = `'gavo.base'`

Function Details

parseModel(modelDescr)

source code

returns a MetaValidator for a model description.

model descriptions are covered in the module docstring.

validateStructure(aStruct)

source code

does a meta validation for a base.Structure.

This works by traversing the children of the structure, looking for nodes with a metaModel attribute. For all these, a validation is carried out. The first node failing the validation determines the return value.

The function raises a MetaValidationError if aStruct is invalid.