Check checks single value with specified rules.

CheckMap validates map and returns the error result.

CheckStruct validates strcut and returns the error result.

RegisterRule registers custom validation rule and function for package.

Error is the validation error for validation result.

CustomMsg is the custom error message type, like: map[field] => string|map[rule]string.

ErrorMap is the validation error map: map[field]map[rule]message.

RuleFunc is the custom function for data validation.