feat(graphql): add graphql endpoint to check whether an entity exists

datahub-graphql-core/src/main/java/com/linkedin/datahub/graphql/GmsGraphQLEngine.java

@@ -86,6 +86,7 @@
 import com.linkedin.datahub.graphql.resolvers.domain.ListDomainsResolver;
 import com.linkedin.datahub.graphql.resolvers.domain.SetDomainResolver;
 import com.linkedin.datahub.graphql.resolvers.domain.UnsetDomainResolver;
+import com.linkedin.datahub.graphql.resolvers.entity.EntityExistsResolver;
 import com.linkedin.datahub.graphql.resolvers.glossary.CreateGlossaryNodeResolver;
 import com.linkedin.datahub.graphql.resolvers.glossary.CreateGlossaryTermResolver;
 import com.linkedin.datahub.graphql.resolvers.glossary.DeleteGlossaryEntityResolver;
@@ -621,6 +622,7 @@ private void configureQueryResolvers(final RuntimeWiring.Builder builder) {
             .dataFetcher("listTests", new ListTestsResolver(entityClient))
             .dataFetcher("getRootGlossaryTerms", new GetRootGlossaryTermsResolver(this.entityClient))
             .dataFetcher("getRootGlossaryNodes", new GetRootGlossaryNodesResolver(this.entityClient))
+            .dataFetcher("getDoesEntityExist", new EntityExistsResolver(this.entityService))
         );
     }
 

datahub-graphql-core/src/main/java/com/linkedin/datahub/graphql/resolvers/entity/EntityExistsResolver.java

@@ -0,0 +1,37 @@
+package com.linkedin.datahub.graphql.resolvers.entity;
+
+import com.linkedin.common.urn.Urn;
+import com.linkedin.metadata.entity.EntityService;
+import graphql.schema.DataFetcher;
+import graphql.schema.DataFetchingEnvironment;
+import java.util.Objects;
+import java.util.concurrent.CompletableFuture;
+
+import static com.linkedin.datahub.graphql.resolvers.ResolverUtils.*;
+
+
+/**
+ * Resolver responsible for returning whether an entity exists.
+ */
+public class EntityExistsResolver implements DataFetcher<CompletableFuture<Boolean>> {
+  private final EntityService _entityService;
+
+  public EntityExistsResolver(final EntityService entityService) {
+    _entityService = entityService;
+  }
+
+  @Override
+  public CompletableFuture<Boolean> get(final DataFetchingEnvironment environment) throws Exception {
+    final String entityUrnString = bindArgument(environment.getArgument("urn"), String.class);
+    Objects.requireNonNull(entityUrnString, "Entity urn must not be null!");
+
+    Urn entityUrn = Urn.createFromString(entityUrnString);
+    return CompletableFuture.supplyAsync(() -> {
+      try {
+        return _entityService.exists(entityUrn);
+      } catch (Exception e) {
+        throw new RuntimeException(String.format("Failed to check whether entity %s exists", entityUrnString));
+      }
+    });
+  }
+}

datahub-graphql-core/src/main/resources/entity.graphql

@@ -158,6 +158,11 @@ type Query {
     Get all GlossaryNodes without a parentNode
     """
     getRootGlossaryNodes(input: GetRootGlossaryEntitiesInput!): GetRootGlossaryNodesResult
+
+    """
+    Get whether or not not an entity exists
+    """
+    getDoesEntityExist(urn: String!): Boolean
 }
 
 """

datahub-graphql-core/src/test/java/com/linkedin/datahub/graphql/resolvers/entity/EntityExistsResolverTest.java

@@ -0,0 +1,41 @@
+package com.linkedin.datahub.graphql.resolvers.entity;
+
+import com.linkedin.metadata.entity.EntityService;
+import graphql.schema.DataFetchingEnvironment;
+import org.testng.annotations.BeforeMethod;
+import org.testng.annotations.Test;
+
+import static org.mockito.Mockito.*;
+import static org.testng.Assert.*;
+
+
+public class EntityExistsResolverTest {
+  private static final String ENTITY_URN_STRING = "urn:li:corpuser:test";
+
+  private EntityService _entityService;
+  private DataFetchingEnvironment _dataFetchingEnvironment;
+  private EntityExistsResolver _resolver;
+
+  @BeforeMethod
+  public void setupTest() {
+    _entityService = mock(EntityService.class);
+    _dataFetchingEnvironment = mock(DataFetchingEnvironment.class);
+
+    _resolver = new EntityExistsResolver(_entityService);
+  }
+
+  @Test
+  public void testFailsNullEntity() {
+    when(_dataFetchingEnvironment.getArgument("urn")).thenReturn(null);
+
+    assertThrows(() -> _resolver.get(_dataFetchingEnvironment).join());
+  }
+
+  @Test
+  public void testPasses() throws Exception {
+    when(_dataFetchingEnvironment.getArgument("urn")).thenReturn(ENTITY_URN_STRING);
+    when(_entityService.exists(any())).thenReturn(true);
+
+    assertTrue(_resolver.get(_dataFetchingEnvironment).join());
+  }
+}