使用promises递归检索分页数据

Question

我正在使用一个以分页形式返回数据的函数.所以它将返回最多100个项目和一个键来检索接下来的100个项目.我想要检索所有可用的项目.

我如何以递归方式实现这一目标？递归是一个不错的选择吗？我可以在没有递归的情况下以任何其他方式进行吗？

我正在使用Bluebird 3x作为promises库.

以下是我想要实现的内容的片段:

getEndpoints(null, platformApplication)
  .then(function(allEndpoints) {
    // process on allEndpoints
  });


function getEndpoints(nextToken, platformApplication) {
  var params = {
    PlatformApplicationArn: platformApplication
  };

  if (nextToken) {
    params.NextToken = nextToken;
  }

  return sns.listEndpointsByPlatformApplicationAsync(params)
    .then(function(data) {
      if (data.NextToken) {
        // There is more data available that I want to retrieve.
        // But the problem here is that getEndpoints return a promise
        // and not the array. How do I chain this here so that 
        // in the end I get an array of all the endpoints concatenated.
        var moreEndpoints = getEndpoints(data.NextToken, platformApplication);
        moreEndpoints.push.apply(data.Endpoints, moreEndpoints);
      }

      return data.Endpoints;
    });
}

但问题是,如果要检索更多数据(请参阅参考资料if (data.NextToken) { ... }),我如何将承诺链接起来,以便最终获得所有端点的列表等.

Answer 1

递归可能是获取所有端点的最简单方法.

function getAllEndpoints(platformApplication) {
    return getEndpoints(null, platformApplication);
}

function getEndpoints(nextToken, platformApplication, endpoints = []) {
  var params = {
    PlatformApplicationArn: platformApplication
  };

  if (nextToken) {
    params.NextToken = nextToken;
  }

  return sns.listEndpointsByPlatformApplicationAsync(params)
    .then(function(data) {
      endpoints.push.apply(endpoints, data.Endpoints);
      if (data.NextToken) {
          return getEndpoints(data.NextToken, platformApplication, endpoints);
      } else {
          return endpoints;
      }
    });
}