Package com.vaadin.flow.server.auth

Interface AccessCheckDecisionResolver

All Superinterfaces:

Serializable

All Known Implementing Classes:

DefaultAccessCheckDecisionResolver

Functional Interface:

This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.

@FunctionalInterface
public interface AccessCheckDecisionResolver
extends Serializable

Indicates a class that is responsible for taking a decisions about granting access to a target view, based on the result provided by NavigationAccessCheckers.

The component is used by NavigationAccessControl to compute the final decision, based on the results of all registered NavigationAccessCheckers.

Method Summary

Modifier and Type	Method	Description
AccessCheckResult	resolve(List<AccessCheckResult> results, NavigationContext context)	Determines if access is granted for a specific navigation context, based on the decisions provided by NavigationAccessCheckers.

Method Details

resolve

AccessCheckResult resolve(List<AccessCheckResult> results,
 NavigationContext context)

Determines if access is granted for a specific navigation context, based on the decisions provided by NavigationAccessCheckers.

The decision resolver should grant access or deny it by returning an appropriate AccessCheckResult object.

The expected result of the method should be AccessCheckDecision.ALLOW or AccessCheckDecision.DENY, or AccessCheckDecision.REJECT.

A AccessCheckDecision.NEUTRAL result does not make because it does not provide meaningful information to NavigationAccessControl to complete the access check process. For this reason, a neutral result will produce the same effect as AccessCheckDecision.REJECT, preventing the navigation and failing with an exception in development mode.

 AccessCheckResult resolve(List<Result> results,
         NavigationContext context) {

     Map<Decision, Long> votes = results.stream()
             .collect(groupingBy(Result::decision, counting()));

     int allow = votes.getOrDefault(Decision.ALLOW, 0L).intValue();
     int deny = votes.getOrDefault(Decision.ALLOW, 0L).intValue();
     int diff = allow - deny;

     if (allow == 0 && deny == 0) {
         return AccessCheckResult.neutral();
     } else if (diff > 0) {
         return AccessCheckResult.allow();
     } else if (diff < 0) {
         return AccessCheckResult.deny(String
                 .format("Allow %d - Deny %d. Deny wins!", allow, deny));
     }
     return AccessCheckResult
             .reject("To allow, or not to allow, that is the question.");
 }
 

Result object can also be created using NavigationContext helpers NavigationContext.allow(), NavigationContext.deny(String), NavigationContext.reject(String) and NavigationContext.neutral().

Parameters:

results - the decisions from access checkers.

context - the current navigation context

Returns:

a result indicating weather the access to target view should be granted or not, never null.