Interface HasValidation<VN, WithPlugins>

The HasValidation interfaces encapsulates properties involved in validation.

• The validate property defines the types for each possible Formio validator, e.g. a pattern must be a string, while a maxLength must be a number. Open Forms also supports backend validators that are called async, which is specified as a list of strings for the validator names.
• The errors property defines the (translated) error messages that may be returned by the backend, at runtime. The possible keys are coupled with the possible validator names in the validate property. The resulting strings are the strings that are ultimately presented to the end user.
• The translatedErrors property is used to store the translated error messages. The keys are the supported language codes, the values have the same shape as the errors property. Effectively, at runtime, this object is assigned for the active language: Object.assign(obj.errors, obj.translatedErrors[activeLanguage]).

There are some generics involed:

• VN: the relevant validator names. Most components only use a small subset of validator options depending on their type. E.g. a pattern makes no sense for a number field, only for textfield/textarea etc. Likewise, max only has meaning for numbers, but not for strings. Typically you pass in a union: 'pattern' | 'maxLength'. This generic is then used to populate the errors and translatedErrors objects with only the relevant keys.
• WithPlugins - most components support plugin validation, but the error messages come from the server. The plugins key is never included in the errors and translatedErrors objects. Pass false if plugin validation is not available for the component.