CERNY.schema

The schema package provides functions for validating a JavaScript object against a schema. A schema is a JavaScript object describing a shape (form, schema, pattern). It is composed of constraints, which have a name and a value. These constraints are the members of the schema. The name of the constraint is mapped on an constraint value, which can be a primitive value, a function, a regular expression or a schema.

The function validate is used to perform validation of an object against a schema. It returns an object (called validation report), which contains an error message for every constraint of the schema, that the object does not conform to. Thus the report builds up the *same structure* as the the schema. If the object conforms to the schema, validate returns an empty object. For convenience the function isValid takes a validation report and returns true for an empty result and false, if the report contains errors.

If the constraint value is a function this can be used within the function to navigate to properties within the object. With this._parent you can navigate up the object tree. Thus it is not recommended to perform validation on objects that do contain a _parent property. When specifying a schema, you should not use the _parent property either.

If the constraint value is a function the following rules apply. The function must return true, if the value of the object fulfills the constraint, otherwise the function should return a String containing an error message or false, which will produce a generic error message. Exceptions that occur within the function are considered an error message also.