feat: add initial support for restricted keys query provider implementation

[igdianov]

This PR adds support for row filtering via restricting query search criteria using pluggable RestrictedKeysProvider implementation.

The RestrictedKeysProvider functional interface should provide a list of restricted keys in order to filter records at runtime based on user security context and supplied EntityIntrospection descriptor arugment.

The return argument uses Optional<List> return type.

• The non-empty list will restrict the query results to provided keys
• The empty list will execute the query without any restrictions.
• The empty Optional will block running the query and return empty result list or null value.

@FunctionalInterface
public interface RestrictedKeysProvider extends Function<EntityIntrospectionResult, Optional<List<Object>>> {

    /**
     * Applies this restricted keys provider function to the given argument of entityDescriptor.
     *
     * @param entityDescriptor the function argument
     * @return the function result with optional list of keys
     */
    @Override
    Optional<List<Object>> apply(EntityIntrospectionResult entityDescriptor);
    
}

You can configure the implementation of the provider via GraphqJpaSchemaBuilder.restrictedKeysProvider builder method Java Api, i.e.,

graphQLSchemaBuilder = GraphQLJpaSchemaBuilder(entityManager)
                .name("GraphQLBooks")
                .description("Books JPA test schema")
                .restrictedKeysProvider(new SpringSecurityRestrictedKeysProvider(entityManager.getMetamode()));

public class SpringSecurityRestrictedKeysProvider implements RestrictedKeysProvider {
    
    private final Metamodel metamodel;
    
    public SpringSecurityRestrictedKeysProvider(Metamodel metamodel) {
        this.metamodel = metamodel;
    }

    @Override
    public Optional<List<Object>> apply(EntityIntrospectionResult entityDescriptor) {
        Authentication token = SecurityContextHolder.getContext()
                                                    .getAuthentication();
        if (token == null) {
            return Optional.empty();
        }
        
        // resolve entity name from descriptor
        String entityName = metamodel.entity(entityDescriptor.getEntity())
                                     .getName();

        // resolve keys from entityName and user token in permission store
        List<Object> keys = resolveKeys(entityName, token);

        return keys.isEmpty() ? Optional.empty() // restrict query if no permissions exists 
                              : Optional.of(keys); // execute query with restricted keys
    }
    

The provided graphql-jpa-query-boot-starter will detect and automatically inject RestrictedKeysProvider bean instance from application context.

Fixes #219

[codecov]

Codecov Report

Merging #274 into master will increase coverage by 2.38%.
The diff coverage is 89.87%.

@@             Coverage Diff              @@
##             master     #274      +/-   ##
============================================
+ Coverage     72.14%   74.53%   +2.38%     
- Complexity     1031     1083      +52     
============================================
  Files            72       72              
  Lines          4696     4751      +55     
  Branches        672      679       +7     
============================================
+ Hits           3388     3541     +153     
+ Misses         1019      919     -100     
- Partials        289      291       +2     

Impacted Files	Coverage Δ	Complexity Δ
...query/schema/relay/GraphQLJpaRelayDataFetcher.java	93.75% <81.81%> (+93.75%)	6.00 <0.00> (+6.00)
...jpa/query/schema/impl/GraphQLJpaSchemaBuilder.java	90.76% <88.88%> (+2.05%)	141.00 <2.00> (+12.00)
.../jpa/query/schema/impl/GraphQLJpaQueryFactory.java	78.91% <89.13%> (+0.54%)	229.00 <7.00> (+9.00)
...utoconfigure/GraphQLJpaQueryAutoConfiguration.java	100.00% <100.00%> (ø)	1.00 <0.00> (ø)
.../query/schema/impl/GraphQLJpaQueryDataFetcher.java	93.18% <100.00%> (+3.18%)	9.00 <0.00> (+2.00)
...phql/jpa/query/schema/impl/EntityIntrospector.java	71.22% <0.00%> (+0.71%)	8.00% <0.00%> (ø%)
...res/graphql/jpa/query/schema/impl/PagedResult.java	88.88% <0.00%> (+3.70%)	6.00% <0.00%> (+1.00%)
.../graphql/jpa/query/introspection/Constructors.java	82.00% <0.00%> (+4.00%)	15.00% <0.00%> (+1.00%)
...query/schema/impl/GraphQLJpaSimpleDataFetcher.java	100.00% <0.00%> (+7.69%)	5.00% <0.00%> (ø%)
... and 4 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update dae311b...c9cfac7. Read the comment docs.