Add listDocuments() API

google-cloud-clients/google-cloud-firestore/src/main/java/com/google/cloud/firestore/CollectionReference.java

@@ -19,7 +19,14 @@
 import com.google.api.core.ApiFunction;
 import com.google.api.core.ApiFuture;
 import com.google.api.core.ApiFutures;
+import com.google.api.gax.rpc.ApiException;
+import com.google.api.gax.rpc.ApiExceptions;
+import com.google.cloud.firestore.v1beta1.FirestoreClient.ListDocumentsPagedResponse;
 import com.google.common.base.Preconditions;
+import com.google.firestore.v1beta1.Document;
+import com.google.firestore.v1beta1.DocumentMask;
+import com.google.firestore.v1beta1.ListDocumentsRequest;
+import java.util.Iterator;
 import java.util.Map;
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
@@ -104,6 +111,62 @@ public DocumentReference document(@Nonnull String childPath) {
     return new DocumentReference(firestore, documentPath);
   }
 
+  /**
+   * Retrieves the list of documents in this collection.
+   *
+   * <p>The document references returned may include references to "missing documents", i.e.
+   * document locations that have no document present but which contain subcollections with
+   * documents. Attempting to read such a document reference (e.g. via `get()` or `onSnapshot()`)
+   * will return a `DocumentSnapshot` whose `exists()` method returns false.
+   *
+   * @return {Promise<DocumentReference[]>} @return {Promise<DocumentReference[]>} The list of
+   *     documents in this * collection.
+   */
+  @Nonnull
+  public Iterable<DocumentReference> listDocuments() {
+    ListDocumentsRequest.Builder request = ListDocumentsRequest.newBuilder();
+    request.setParent(path.getParent().toString());
+    request.setCollectionId(this.getId());
+    request.setMask(DocumentMask.getDefaultInstance());
+    request.setShowMissing(true);
+
+    final ListDocumentsPagedResponse response;
+
+    try {
+      response =
+          ApiExceptions.callAndTranslateApiException(
+              firestore.sendRequest(
+                  request.build(), firestore.getClient().listDocumentsPagedCallable()));
+    } catch (ApiException exception) {
+      throw FirestoreException.apiException(exception);
+    }
+
+    return new Iterable<DocumentReference>() {
+      @Override
+      @Nonnull
+      public Iterator<DocumentReference> iterator() {
+        final Iterator<Document> iterator = response.iterateAll().iterator();
+        return new Iterator<DocumentReference>() {
+          @Override
+          public boolean hasNext() {
+            return iterator.hasNext();
+          }
+
+          @Override
+          public DocumentReference next() {
+            ResourcePath path = ResourcePath.create(iterator.next().getName());
+            return document(path.getId());
+          }
+
+          @Override
+          public void remove() {
+            throw new UnsupportedOperationException("remove");
+          }
+        };
+      }
+    };
+  }
+
   /**
    * Adds a new document to this collection with the specified data, assigning it a document ID
    * automatically.

google-cloud-clients/google-cloud-firestore/src/main/java/com/google/cloud/firestore/spi/v1beta1/FirestoreRpc.java

@@ -21,20 +21,21 @@
 import com.google.api.gax.rpc.UnaryCallable;
 import com.google.cloud.ServiceRpc;
 import com.google.cloud.firestore.v1beta1.FirestoreClient.ListCollectionIdsPagedResponse;
+import com.google.cloud.firestore.v1beta1.FirestoreClient.ListDocumentsPagedResponse;
 import com.google.firestore.v1beta1.BatchGetDocumentsRequest;
 import com.google.firestore.v1beta1.BatchGetDocumentsResponse;
 import com.google.firestore.v1beta1.BeginTransactionRequest;
 import com.google.firestore.v1beta1.BeginTransactionResponse;
 import com.google.firestore.v1beta1.CommitRequest;
 import com.google.firestore.v1beta1.CommitResponse;
 import com.google.firestore.v1beta1.ListCollectionIdsRequest;
+import com.google.firestore.v1beta1.ListDocumentsRequest;
 import com.google.firestore.v1beta1.ListenRequest;
 import com.google.firestore.v1beta1.ListenResponse;
 import com.google.firestore.v1beta1.RollbackRequest;
 import com.google.firestore.v1beta1.RunQueryRequest;
 import com.google.firestore.v1beta1.RunQueryResponse;
 import com.google.protobuf.Empty;
-import java.util.concurrent.Executor;
 import java.util.concurrent.ScheduledExecutorService;
 
 /** Contains the RPC stubs used by the manual Cloud Firestore client. */
@@ -63,6 +64,9 @@ public interface FirestoreRpc extends AutoCloseable, ServiceRpc {
   UnaryCallable<ListCollectionIdsRequest, ListCollectionIdsPagedResponse>
       listCollectionIdsPagedCallable();
 
+  /** Returns a list of documents. */
+  UnaryCallable<ListDocumentsRequest, ListDocumentsPagedResponse> listDocumentsPagedCallable();
+
   /** Returns a bi-directional watch stream. */
   BidiStreamingCallable<ListenRequest, ListenResponse> listenCallable();
 }

google-cloud-clients/google-cloud-firestore/src/main/java/com/google/cloud/firestore/spi/v1beta1/GrpcFirestoreRpc.java

@@ -33,10 +33,11 @@
 import com.google.cloud.NoCredentials;
 import com.google.cloud.ServiceOptions;
 import com.google.cloud.firestore.FirestoreOptions;
-import com.google.cloud.firestore.v1beta1.FirestoreSettings;
-import com.google.cloud.firestore.v1beta1.stub.FirestoreStubSettings;
 import com.google.cloud.firestore.v1beta1.FirestoreClient.ListCollectionIdsPagedResponse;
+import com.google.cloud.firestore.v1beta1.FirestoreClient.ListDocumentsPagedResponse;
+import com.google.cloud.firestore.v1beta1.FirestoreSettings;
 import com.google.cloud.firestore.v1beta1.stub.FirestoreStub;
+import com.google.cloud.firestore.v1beta1.stub.FirestoreStubSettings;
 import com.google.cloud.firestore.v1beta1.stub.GrpcFirestoreStub;
 import com.google.cloud.grpc.GrpcTransportOptions;
 import com.google.cloud.grpc.GrpcTransportOptions.ExecutorFactory;
@@ -48,6 +49,7 @@
 import com.google.firestore.v1beta1.CommitResponse;
 import com.google.firestore.v1beta1.DatabaseRootName;
 import com.google.firestore.v1beta1.ListCollectionIdsRequest;
+import com.google.firestore.v1beta1.ListDocumentsRequest;
 import com.google.firestore.v1beta1.ListenRequest;
 import com.google.firestore.v1beta1.ListenResponse;
 import com.google.firestore.v1beta1.RollbackRequest;
@@ -59,7 +61,6 @@
 import io.grpc.ManagedChannelBuilder;
 import java.io.IOException;
 import java.util.Collections;
-import java.util.concurrent.Executor;
 import java.util.concurrent.ScheduledExecutorService;
 
 /**
@@ -129,7 +130,8 @@ public Void apply(UnaryCallSettings.Builder<?, ?> builder) {
             }
           };
       FirestoreStubSettings.Builder firestoreBuilder =
-          FirestoreStubSettings.newBuilder(clientContext).applyToAllUnaryMethods(retrySettingsSetter);
+          FirestoreStubSettings.newBuilder(clientContext)
+              .applyToAllUnaryMethods(retrySettingsSetter);
       firestoreStub = GrpcFirestoreStub.create(firestoreBuilder.build());
     } catch (Exception e) {
       throw new IOException(e);
@@ -187,6 +189,12 @@ public UnaryCallable<RollbackRequest, Empty> rollbackCallable() {
     return firestoreStub.listCollectionIdsPagedCallable();
   }
 
+  @Override
+  public UnaryCallable<ListDocumentsRequest, ListDocumentsPagedResponse>
+      listDocumentsPagedCallable() {
+    return firestoreStub.listDocumentsPagedCallable();
+  }
+
   @Override
   public BidiStreamingCallable<ListenRequest, ListenResponse> listenCallable() {
     return firestoreStub.listenCallable();

google-cloud-clients/google-cloud-firestore/src/test/java/com/google/cloud/firestore/it/ITSystemTest.java

@@ -577,6 +577,39 @@ public void getCollections() throws Exception {
     assertEquals(collections.length, count);
   }
 
+  @Test
+  public void listDocuments() throws Exception {
+    // We test with 21 documents since 20 documents are by default returned in a single paged
+    // response.
+    String[] documents =
+        new String[] {
+          "1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12", "13", "14", "15", "16",
+          "17", "18", "19", "20", "21"
+        };
+    Arrays.sort(documents); // Sort in alphabetical (non-numeric) order.
+
+    WriteBatch batch = firestore.batch();
+    for (String document : documents) {
+      batch.create(randomColl.document(document), SINGLE_FIELD_OBJECT);
+    }
+    batch.commit().get();
+
+    Iterable<DocumentReference> collectionRefs = randomColl.listDocuments();
+
+    int count = 0;
+    for (DocumentReference documentRef : collectionRefs) {
+      assertEquals(documents[count++], documentRef.getId());
+    }
+    assertEquals(documents.length, count);
+  }
+
+  @Test
+  public void listDocumentsListsMissingDocument() throws Exception {
+    randomColl.document("missing/foo/bar").set(SINGLE_FIELD_MAP).get();
+    Iterable<DocumentReference> collectionRefs = randomColl.listDocuments();
+    assertEquals(randomColl.document("missing"), collectionRefs.iterator().next());
+  }
+
   @Test
   public void addAndRemoveFields() throws ExecutionException, InterruptedException {
     Map<String, Object> expected = new HashMap<>();