JSON validation for Pecan with Notario (http://notario.cafepais.com).
In its simplest form, you need to define a schema and decorate the controller method, like:
schema = ('foo', True) @expose() @validate(schema) def some_controller(self, **kw): return dict()
The above controller method, using a Notario schema, will require a foo key and a True value otherwise it will (by default) set the HTTP response to a 400 (invalid request) and add the validation error to request.pecan['schema'].errors.
Using a handler
If more granular control is needed when dealing with an error condition, a handler can be passed in to the decorator to deal with errors explicitly.
@expose() @validate(some_schema, '/some/handler') def some_controller(self, **kw): return dict()
In this situation ‘/some/handler’ would be a controller method that can deal directly with the error that was slapped onto the request object (on request.validation_error).
Notario exceptions will include a reason attribute that will contain the specific error message that was raised if a custom validator failed with an error message. In this case, a handler would access this Notario exception attribute like: