Expectation Suite Operations

A Great Expectations Expectation Suite enables you to perform Create, Read, Update, and Delete (CRUD) operations on a Suite's Expectations without needing to re-run them. Each of the methods that support a CRUD operation relies on two main parameters - expectation_configuration and match_type.

• expectation_configuration - an ExpectationConfiguration object that is used to determine whether and where this Expectation already exists within the Suite. It can be a complete or a partial ExpectationConfiguration.
• match_type - a string with the value of domain, success, or runtime which determines the criteria used for matching:
  • domain checks whether two Expectation Configurations apply to the same data. It results in the loosest match, and can use the least complete ExpectationConfiguration object. For example, for a column map Expectation, domain_kwargs will include the Expectation_type, the column, and any row_conditions that may affect which rows are evaluated by the Expectation.
  • success criteria are more exacting - in addition to the domain kwargs, these include those kwargs used when evaluating the success of an Expectation, like mostly, max, or value_set.
  • runtime are the most specific - in addition to domain_kwargs and success_kwargs, these include kwargs used for runtime configuration. Currently these include result_format, include_config, and catch_exceptions

Adding or updating Expectations

To add an Expectation to a Suite, you can use

Python

suite.add_expectation_configuration(
    expectation_configuration,
    match_type,
    overwrite_existing
)

• If a matching Expectation is not found on the Suite, this function will add the Expectation to the Suite.
• If a matching Expectation is found on the Suite, add_expectation will throw an error, unless overwrite_existing is set to True, in which case the found Expectation will be updated with expectation_configuration.
• If more than one Expectation is found, this will throw an error, and you will be prompted to be more specific with your matching criteria.

Removing Expectations

To remove an Expectation from an Expectation Suite, you can use

Python

suite.remove_expectation(
    expectation_configuration, 
    match_type, 
    remove_multiple_matches
)

• If this finds one matching Expectation, it will remove it.
• If it finds more than one matching Expectation, it will throw an error, unless remove_multiple_matches is set to True, in which case it will remove all matching Expectations.
• If this finds no matching Expectations, it will throw an error.

If you are interactively working with an Expectation Suite using a Validator, you can access this functionality by directly calling

Python

validator.remove_expectation(
    expectation_configuration, 
    match_type, 
    remove_multiple_matches
)