Updating state management example to include etag mismatch exception handling

examples/src/main/java/io/dapr/examples/state/README.md

@@ -80,17 +80,30 @@ public class StateClient {
         retrievedMessagesMono.block().forEach(System.out::println);
 
         System.out.println("Deleting states...");
-
+
+        System.out.println("Verify delete key request is aborted if an etag different from stored is passed.");
         // delete state API
-        Mono<Void> mono = client.deleteState(STATE_STORE_NAME, FIRST_KEY_NAME);
-        mono.block();
+        try {
+          client.deleteState(STATE_STORE_NAME, FIRST_KEY_NAME, "100", null).block();
+        } catch (DaprException ex) {
+          if (ex.getErrorCode().equals(Status.Code.ABORTED.toString())) {
+            // Expected error due to etag mismatch.
+            System.out.println(String.format("Expected failure. %s ", ex.getMessage()));
+          } else {
+            System.out.println("Unexpected exception.");
+            throw ex;
+          }
+        }
+
+        System.out.println("Trying to delete again with correct etag.");
+        String storedEtag = client.getState(STATE_STORE_NAME, FIRST_KEY_NAME, MyClass.class).block().getEtag();
+        client.deleteState(STATE_STORE_NAME, FIRST_KEY_NAME, storedEtag, null).block();
 
         // Delete operation using transaction API
         operationList.clear();
         operationList.add(new TransactionalStateOperation<>(TransactionalStateOperation.OperationType.DELETE,
             new State<>(SECOND_KEY_NAME)));
-        mono = client.executeStateTransaction(STATE_STORE_NAME, operationList);
-        mono.block();
+        client.executeStateTransaction(STATE_STORE_NAME, operationList).block();
 
         Mono<List<State<MyClass>>> retrievedDeletedMessageMono = client.getStates(STATE_STORE_NAME,
             Arrays.asList(FIRST_KEY_NAME, SECOND_KEY_NAME), MyClass.class);
@@ -112,7 +125,7 @@ This example performs multiple operations:
 * `client.getState(...)` operation in order to retrieve back the persisted state using the same key. 
 * `client.executeStateTransaction(...)` operation in order to update existing state and add new state. 
 * `client.getBulkState(...)` operation in order to retrieve back the persisted states using the same keys.
-* `client.deleteState(...)` operation to remove  one of the persisted states. 
+* `client.deleteState(...)` operation to remove  one of the persisted states. An example of etag mismatch error if a different than current etag is added to request.
 * `client.executeStateTransaction(...)` operation in order to remove the other persisted state.
 
 Finally, the code tries to retrieve the deleted states, which should not be found. 

examples/src/main/java/io/dapr/examples/state/StateClient.java

@@ -9,6 +9,8 @@
 import io.dapr.client.DaprClientBuilder;
 import io.dapr.client.domain.State;
 import io.dapr.client.domain.TransactionalStateOperation;
+import io.dapr.exceptions.DaprException;
+import io.grpc.Status;
 import reactor.core.publisher.Mono;
 
 import java.util.ArrayList;
@@ -84,16 +86,28 @@ public static void main(String[] args) throws Exception {
 
       System.out.println("Deleting states...");
 
+      System.out.println("Verify delete key request is aborted if an etag different from stored is passed.");
       // delete state API
-      Mono<Void> mono = client.deleteState(STATE_STORE_NAME, FIRST_KEY_NAME);
-      mono.block();
-
+      try {
+        client.deleteState(STATE_STORE_NAME, FIRST_KEY_NAME, "100", null).block();
+      } catch (DaprException ex) {
+        if (ex.getErrorCode().equals(Status.Code.ABORTED.toString())) {
+          // Expected error due to etag mismatch.
+          System.out.println(String.format("Expected failure. %s ", ex.getMessage()));
+        } else {
+          System.out.println("Unexpected exception.");
+          throw ex;
+        }
+      }
+
+      System.out.println("Trying to delete again with correct etag.");
+      String storedEtag = client.getState(STATE_STORE_NAME, FIRST_KEY_NAME, MyClass.class).block().getEtag();
+      client.deleteState(STATE_STORE_NAME, FIRST_KEY_NAME, storedEtag, null).block();
       // Delete operation using transaction API
       operationList.clear();
       operationList.add(new TransactionalStateOperation<>(TransactionalStateOperation.OperationType.DELETE,
           new State<>(SECOND_KEY_NAME)));
-      mono = client.executeStateTransaction(STATE_STORE_NAME, operationList);
-      mono.block();
+      client.executeStateTransaction(STATE_STORE_NAME, operationList).block();
 
       Mono<List<State<MyClass>>> retrievedDeletedMessageMono = client.getBulkState(STATE_STORE_NAME,
           Arrays.asList(FIRST_KEY_NAME, SECOND_KEY_NAME), MyClass.class);

sdk/src/main/java/io/dapr/client/domain/State.java

@@ -26,7 +26,7 @@ public class State<T> {
 
   /**
    * The ETag to be used
-   * Keep in mind that for some state stores (like reids) only numbers are supported.
+   * Keep in mind that for some state stores (like redis) only numbers are supported.
    */
   private final String etag;