Function If

markers/markers.go:151–158

If iterates on the error's causal chain and returns a predicate's return value the first time the predicate returns true. Note: if any of the error types has been migrated from a previous package location or a different type, ensure that RegisterTypeMigration() was called prior to If().

(err error, pred func(err error) (interface{}, bool))

// package location or a different type, ensure that
// RegisterTypeMigration() was called prior to If().
func If(err error, pred func(err error) (interface{}, bool)) (interface{}, bool) {
	for c := err; c != nil; c = errbase.UnwrapOnce(c) {
		if v, ok := pred(c); ok {
			return v, ok
		}
	}
	return nil, false
}

// IsAny is like Is except that multiple references are compared.
//