Google数据存储中的节点分页 [英] Node pagination in google datastore

问题描述

我在使用Google数据存储区分页时遇到问题。我有一个没有限制的查询有几百个结果。我想检索5，发回给用户，如果用户想要更多，他们会检索下5个。

I am having trouble doing the pagination with Google Datastore. I have a query which without the limit has a few hundred results. I would like to retrieve 5, send them back to the user, if the user wants more they would retrieve the next 5.

按照文档我创建查询：

var query = datastore.createQuery('ResultsKind').filter('name', 'bobby').limit(5).autoPaginate(false);

然后我运行这个查询来得到前5个结果：

I then run this query to get the first 5 results:

datastore.runQuery(query, callback);

这是回调函数：

This is the callback function:

function callback(err, entities, nextQuery, apiResponse) {
    if (err) {
        // An error occurred while running the query.
        console.log('err ' + err);
        return;
    }

    if (nextQuery) {
        console.log('res = ' + entities);
        datastore.runQuery(nextQuery, callback);
    } else {
        // No more results exist.
        console.log('no more results');
        return;
    }
};

问题是正在打印 res = 无限次，在控制台中没有结果。我不确定我做错了什么。我想要发生的是。

The problem is res = is being printed infinity times with no results in the console. I am unsure what I am doing wrong. What I would like to happen is.

1) I create the initial query.
2) I run the query.
3) I get the first 5 results.
4) I pass these results + the nextquery object to the user.
5) If the user wants more results the pass me back the nextQuery and I run this query and get the next 5 results and so on.

我一直在寻找这份文件： http://googlecloudplatform.github.io/gcloud-node/#/docs/v0.30.2/数据存储/查询？method = autoPaginate 。

I have been looking at this doc:http://googlecloudplatform.github.io/gcloud-node/#/docs/v0.30.2/datastore/query?method=autoPaginate.

我怎样才能完成这个简单的分页？

How can I accomplish this simple pagination?

推荐答案

在您的回调中，您将直接在 console.log 后重新运行查询：

From within your callback, you are re-running the query directly after the console.log:

if (nextQuery) {
    console.log('res = ' + entities);
    datastore.runQuery(nextQuery, callback); // <-- Here
}

这实质上与 autoPaginate（true）的确如此。相反，您应该删除该行，缓存 nextQuery ，然后运行您删除的同一行，以在用户请求时获取下一批结果。

This is essentially doing the same thing as autoPaginate(true) does. Instead, you should remove that line, cache nextQuery, then run the same line that you removed to get the next batch of results when the user asks to.

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