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d3.js, queue.js và node.js

In lại 作者：太空宇宙 更新时间：2023-11-03 21:58:34 28 4
mua khóa gpt4 Nike

我尝试在 NodeJS 中加载数据，然后将其传递给 ExpressJS 以在浏览器中呈现 d3 图表。

我知道我可以通过这种方式加载数据 - https://github.com/mbostock/queue

我有一个像这样的expressjs路由配置 - 

    var d3 = require('d3')
            ,queue = require("queue-async")
            ;

        router.get('/', handler1);

        function handler1(req, res) {

    queue()
       .defer(d3.json, 'https://data.medicare.gov/resource/a8s4-5eya.json?$limit=50000&$$app_token=igGS35vW9GvDMmJUnmHju2MEH&$select=org_pac_id%20as%20source, org_pac_id%20as%20target,org_lgl_nm%20as%20description')
       .defer(d3.json, 'https://data.medicare.gov/resource/a8s4-5eya.json?$limit=50000&$$app_token=igGS35vW9GvDMmJUnmHju2MEH&$select=org_pac_id%20as%20source, org_pac_id||pri_spec%20as%20target, pri_spec%20as%20description')
       .defer(d3.json, 'https://data.medicare.gov/resource/a8s4-5eya.json?$limit=50000&$$app_token=igGS35vW9GvDMmJUnmHju2MEH&$select=org_pac_id||pri_spec%20as%20tsource, pri_spec%20as%20target, frst_nm%20as%20description')
       .await(go);

    function go(error, data,d2,d3){

     data.concat(d2); data.concat(d3);

     console.log(data);

     res.render('index', { title: 'Group Practices', data });

    }  
  }
module.exports = router;

但我收到浏览器错误，

XMLHttpRequest is not defined

ReferenceError: XMLHttpRequest is not defined
    at d3_xhr (/Users/Admin/Public/GroupPractice/node_modules/d3/d3.js:1934:114)
    at d3.json (/Users/Admin/Public/GroupPractice/node_modules/d3/d3.js:9533:12)
    at pop (/Users/Admin/Public/GroupPractice/node_modules/queue-async/queue.js:24:14)
    at Object.q.defer (/Users/Admin/Public/GroupPractice/node_modules/queue-async/queue.js:55:11)
    at handler1 (/Users/Admin/Public/GroupPractice/routes/index.js:18:5)
    at Layer.handle [as handle_request] (/Users/Admin/Public/GroupPractice/node_modules/express/lib/router/layer.js:95:5)
    at next (/Users/Admin/Public/GroupPractice/node_modules/express/lib/router/route.js:131:13)
    at Route.dispatch (/Users/Admin/Public/GroupPractice/node_modules/express/lib/router/route.js:112:3)
    at Layer.handle [as handle_request] (/Users/Admin/Public/GroupPractice/node_modules/express/lib/router/layer.js:95:5)
    at /Users/Admin/Public/GroupPractice/node_modules/express/lib/router/index.js:277:22

如何使用 d3 和队列来预加载此 RESTful 数据？

1 Câu trả lời

d3 库是一个客户端库。这意味着它必须在浏览器中使用，而不是在服务器端应用程序中使用。

如果您想获取数据并在 Express 应用程序中连接它们，您可以使用异步Và请求，如下所述:

var request = require('request');
var async = require('async');

function createRequestTask(url) {
  return function(callback) {
    request({
      url: url,
      json: true        
    }, function (err, response, body) {
      callback(err, body);
    });
  };
}

async.parallel([
  // URL #1
  createRequestTask('https://data.medicare.gov/resource/a8s4-5eya.json?$limit=50000&$$app_token=igGS35vW9GvDMmJUnmHju2MEH&$select=org_pac_id%20as%20source, org_pac_id%20as%20target,org_lgl_nm%20as%20description'),
  // URL #2
  createRequestTask('https://data.medicare.gov/resource/a8s4-5eya.json?$limit=50000&$$app_token=igGS35vW9GvDMmJUnmHju2MEH&$select=org_pac_id%20as%20source, org_pac_id%20as%20target,org_lgl_nm%20as%20description'),
  (...)
],
function(err, results) {
  // Result contains an array with each request result
});

请求将并行执行，当所有请求完成时，调用最终回调。 results 变量将包含一个包含所有响应内容的数组。

然后，您可以利用此数组来构建您希望 Express 路由返回的对象。

这是您的代码的更新:

router.get('/', handler1);

function handler1(req, res) {
  async.parallel([
    // URL #1
    createRequestTask('https://data.medicare.gov/...'),
    // URL #2
    createRequestTask('https://data.medicare.gov/...'),
    (...)
  ],
  function(err, results) {
    res.render('index', { title: 'Group Practices', results });
  });  
}

module.exports = router;

希望对你有帮助蒂埃里

关于node.js - d3.js、queue.js 和 node.js，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/33815684/

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