Error Propagation

Custom validators in FLYNC are raising PydanticCustomErrors, to make sure the workspace is loaded as expected. The different Custom Errors are handled in an error propagation flow that we’ll explore on this page.

Overview

There are 3 types of errors defined:

• Minor

• Major

• Fatal

All of them can be retrieved from the factory functions from flync.core.utils.exceptions and raised directly.

Example:

raise err_minor(
    "{field_type} is wrong type for the field {field_name}",
    field_type=field_type,
    field_name=field_name
)

raise err_major(
    "{field_type} is wrong type for the field {field_name}",
    field_type=field_type,
    field_name=field_name
)

raise err_fatal(
    "{field_type} is wrong type for the field {field_name}",
    field_type=field_type,
    field_name=field_name
)

Tip

It is not mandatory to use ctx keyword arguments, you can simply use an f-string for error message.

Validation policy

The FLYNC Workspace provides a loader that uses following validation policy:

Error Level	Error Handling
minor	Minor errors are usually realted to an indivdual field value and are easy to fix. in the current version of FLYNC, the component with the minor error will not be created. But the validation continues and in case there are only minor issues, the FLYNC model might be created with the list of all collected errors.
major	Major errors are being collected along with minor ones. The validation returns a tuple with no FLYNC model (None) and a list of all collected errors.
fatal	Stops the validation immediately and reraises pydantic’s original ValidationError.

This policy is implemented in flync.core.utils.exceptions_handling.validate_with_policy().