Question

我正在为我的项目使用AWS AppSync。使用突变将数据推送到服务器时它工作正常。但我对订阅有疑问。

OnEventCreated onEventCreated = OnEventCreated.builder().build();
        subscriptionWatcher =  ClientFactory.getInstance(this).subscribe(onEventCreated); // giving error

subscribe函数接受实现Subscription的输入。但是当我构建我的项目时，生成的代码实现了Query。

生成的类

@Generated("Apollo GraphQL")
public final class OnEventCreated implements Query<OnEventCreated.Data, OnEventCreated.Data, Operation.Variables> {
  public static final String OPERATION_DEFINITION = "subscription OnEventCreated {\n"
      + "  onEventCreated {\n"
      + "    __typename\n"
      + "    id\n"
      + "    description\n"
      + "    name\n"
      + "    when\n"
      + "    where\n"
      + "  }\n"
      + "}";

  public static final String QUERY_DOCUMENT = OPERATION_DEFINITION;
}...

GraphQL文件中订阅的特定代码是..

subscription OnEventCreated {
    onEventCreated {
      id
      description
      name
      when
      where
    }
} ...

Schema.json文件

type Subscription {
    subscribeToEventComments(eventId: String!): Comment
        @aws_subscribe(mutations: ["commentOnEvent"])
    onEventCreated: Event
        @aws_subscribe(mutations: ["createEvent"])
}...

构建文件包含...

compile 'com.amazonaws:aws-android-sdk-appsync:2.6.16'
    compile 'com.amazonaws:aws-android-sdk-appsync-compiler:2.6.16'
    compile 'com.amazonaws:aws-android-sdk-cognitoidentityprovider:2.6.16'
    compile 'org.eclipse.paho:org.eclipse.paho.client.mqttv3:1.2.0'
    compile 'org.eclipse.paho:org.eclipse.paho.android.service:1.1.1'

我能做些什么呢。当我构建时，生成的OnEventCreated类实现Subscription接口而不是Query接口

Answer 1

您是否还在GraphQL架构上设置了@aws_subscribe指令，以便在订阅onEventCreated时触发突变？例如，它可能看起来像这样：

type Subscription {
    onEventCreated: Event
    @aws_subscribe(mutations: ["createEvent"])
}

然后，当成功调用createEvent突变时，它将触发订阅。可以在此处找到更多数据：https://docs.aws.amazon.com/appsync/latest/devguide/real-time-data.html

<强>被修改

再次阅读上面的信息后（由于wordwrap错过了一些信息），我看到你得到的错误是：

OnEventCreated onEventCreated = OnEventCreated.builder().build();
subscriptionWatcher = ClientFactory.getInstance(this).subscribe(onEventCreated);

您需要将onEventCreated传递给.createInstance()，如此：

subscriptionWatcher = ClientFactory.createInstance(this).subscribe(subscription);

此时，当您收到如此响应时，您可以对数据执行操作：

    subscriptionWatcher.execute(new AppSyncSubscriptionCall.Callback() {
        @Override
        public void onResponse(@Nonnull Response response) {
            Log.d("RESPONSE", response.data().toString());
        }

        @Override
        public void onFailure(@Nonnull ApolloException e) {
            Log.d("ERROR", e.toString());
        }

        @Override
        public void onCompleted() {
            Log.d("COMPLETE", "COMPLETED SUBSCRIPTION");
        }
    });

生成的GraphQL类实现Query接口而不是Subscription接口

1 个答案: