on_fail Policies for Validators

While initializing a validator, you can specify on_fail policies to handle the failure of the validator. The on_fail policy specifies the corrective action that should be taken if the quality criteria is not met. The corrective action can be one of the following:

Action	Behavior
reask	Reask the LLM to generate an output that meets the correctness criteria specified in the validator. The prompt used for reasking contains information about which quality criteria failed, which is auto-generated by the validator.
fix	Programmatically fix the generated output to meet the correctness criteria when possible. E.g. the formatter provenance_llm validator will remove any sentences that are estimated to be hallucinated.
filter	(Only applicable for structured data validation) Filter the incorrect value. This only filters the field that fails, and will return the rest of the generated output.
refrain	Refrain from returning an output. This is useful when the generated output is not safe to return, in which case a None value is returned instead.
noop	Do nothing. The failure will still be recorded in the logs, but no corrective action will be taken.
exception	Raise an exception when validation fails.
fix_reask	First, fix the generated output deterministically, and then rerun validation with the deterministically fixed output. If validation fails, then perform reasking.