Question

代码全部工作，页面呈现但我得到了大量的错误并且之前只将数据集的第一行写入控制台 res.render被称为。{/ p>

Error: Can't set headers after they are sent.    
    at ServerResponse.OutgoingMessage.setHeader (_http_outgoing.js:344:11)
    at ServerResponse.header      (C:\Node\NodeTestTed\nodetestted\node_modules\express\lib\response.js:718:10)

    at ServerResponse.contentType (C:\Node\NodeTestTed\nodetestted\node_modules\
    express\lib\response.js:551:15)
    at ServerResponse.send (C:\Node\NodeTestTed\nodetestted\node_modules\express
    \lib\response.js:138:14)
    at done (C:\Node\NodeTestTed\nodetestted\node_modules\express\lib\response.j
    s:957:10)
        at Object.exports.renderFile (C:\Node\NodeTestTed\nodetestted\node_modules\j
    ade\lib\index.js:374:12)
        at View.exports.__express [as engine] (C:\Node\NodeTestTed\nodetestted\node_
    modules\jade\lib\index.js:417:11)
        at View.render (C:\Node\NodeTestTed\nodetestted\node_modules\express\lib\vie
    w.js:126:8)
        at tryRender (C:\Node\NodeTestTed\nodetestted\node_modules\express\lib\appli
    cation.js:639:10)
        at EventEmitter.render (C:\Node\NodeTestTed\nodetestted\node_modules\express
    \lib\application.js:591:3)
    GET /stylesheets/style.css 304 1.596 ms - -

res.render is called immediatly after the first row is returned from Tedious

以下是代码：

var express = require('express');
var Promise = require('promise');

var router = express.Router();

/* GET home page. */
router.get('/', getClients, function(req, res, next) {
  console.log("one");
  res.render('index', { title: 'Hi There. ' });
});

router.get('/helloworld', function(req, res) {
    res.render('helloworld', {title: 'Hello World'});

});



function getClients(req, res, next) {
    var promise = new Promise(function(fulfill, reject){
    var dataset = [];

    var Connection = require('tedious').Connection;
    var Request = require('tedious').Request;
    var config = {
        server: '****',
        userName: '*****',
        password: '****',
        options: {
            instanceName: '****'
        }
    };

    var connection = new Connection(config);

    connection.on('connect', function (err) {
        if (err) {
            console.log(err);
            //res.statusCode = 500;
            // return res.json({ errors:[err] });
        } else {
            // If no error, then good to go...

            executeStatement();
            //console.log("hi");
        }
    });

    function executeStatement() {
    //var promise = new Promise(function(resolve, reject){


     var sql = "select people.people_id, evolv_cs.dbo.formatname(people.last_name, people.first_name, people.middle_name) as client " +
          " from  evolv_cs.dbo.people  join evolv_cs.dbo.event_log " +
          "on event_log.people_id = people.people_id " +
          " and event_log.event_definition_id = 'BA7EF74D-142D-4884-981A-6153755DFBE9' " + // program enrollment
          " and event_log.program_providing_service = '1D955DBF-529C-42D3-A2DA-C77B2036F642' " +   // Central Star PHF - Adolescent
          "  where   event_log.end_date is null ";

     var Request = require('tedious').Request;
     request = new Request(sql, function (err, rowCount) {
          if (err) {
               console.log(err);
               //callback(err);
               reject(err);
          } else {
           if(rowCount < 1) {
               callback(null, false);
           }
           else {
               //callback (null, newdata);
            fulfill(dataset);
           }
          }
     });


     request.on('row', function (columns) {

          columns.forEach(function (column) {
               console.log(column.value);

               dataset.push({
                col: column.metadata.colName,
                   val: column.value
               });
          });
          //newdata.push(dataset);
          //req.Clients = dataset;
          //req.body = dataset;
         // console.log(req.body);



          next();


     });


     request.on('doneProc', function (rowCount, more, returnStatus, rows) {
          //console.log('What TF');
          /*  arlen = values.length;
            for (i = 0; i < arlen; i++) {
                 console.log(values[i]); 
            }   */

          connection.close()
          console.log('zzz');


       //arr = values;
       //   console.log(arr[0]);

     });
     connection.execSql(request);
    // return resolve(dataset);   
    //});
     }
  });
    //console.log(dataset);

    // end of getclients

}



module.exports = router;

Answer 1

因为你在next()内呼叫request.on('row', ...。当你调用next时，它返回控制权以表示调用下一个中间件函数。

传递给request.on('row', ...的函数将针对查询返回的每一行调用一次。一旦掌握了所有结果，您真的只想打电话给next()。

因此，您需要将next()调用移至以下内容：

request.on('done', function (rowCount, more, rows) {
  // process rows
  next(null, rows);
});

如何在表达res.render之前获取整个结果集

1 个答案: