在Express路由之间传递数据以创建两个响应

Question

I have a project where when the user presses the submit button it sends the the data 'to' and 'from' to '/charts' on my server, which is express.js. (Below is some of my pug script).

//index.pug    
form(action="/charts" method="get")
            select
                    option(value='chart') Chart
                    option(value='report') Report
            p From:
                    input(type='date' id='from' name='from')
            p To:
                    input(type='date' id='to' name='to')
            input(type="submit" value="Submit")

On the server side, I want to be able to use the data the user has just submitted in an SQL query, the result of which will be sent as JSON to my client-side JavaScript which creates some google charts visualizations.

//server.js
app.get('/charts', function(req, res, next) {

    var to = req.params.to;
    var from = req.params.from;

    console.log("Dates /dateRange " + to + " - " + from);

    //SQL Query
    connection.query("select date_, count(*) AS 'Total' from ( select date(insert_timestamp) date_ from test_table where api_task_type='hifd' AND insert_timestamp BETWEEN '" + from + "' AND '" + to + "')a group by date_ order by date_", function(err, rows, fields){
    if(!err){
    var table = [];
    for (var i in rows) {
            table.push({
                    date: String(rows[i].date_.getFullYear() + '-' + (rows[i].date_.getMonth() + 1) + "-" + rows[i].date_.getDate()),
                            Record_Count: (rows[i].Total),
                    });
            console.log(rows[i]);
    }
    console.log("The JSON data is: " + table);
    res.json(table);
    }
});

});

The problem I am having is that, along with sending the json data, I want to render my visualization page (chart.pug), but express doesnt allow you to send more than one response. So I would like something like:

app.get('/chartQuery', function(req, res, next) {

    var to = req.params.to;
    var from = req.params.from;

    console.log("Dates /dateRange " + to + " - " + from);

    //SQL Query
    connection.query("select date_, count(*) AS 'Total' from ( select date(insert_timestamp) date_ from test_table where api_task_type='hifd' AND insert_timestamp BETWEEN '" + from + "' AND '" + to + "')a group by date_ order by date_", function(err, rows, fields){
    if(!err){
    var table = [];
    for (var i in rows) {
            table.push({
                    date: String(rows[i].date_.getFullYear() + '-' + (rows[i].date_.getMonth() + 1) + "-" + rows[i].date_.getDate()),
                            Record_Count: (rows[i].Total),
                    });
            console.log(rows[i]);
    }
    var stringtable = JSON.stringify(table);
    console.log("The JSON data is: " + table);
    res.json(table);
    //Render the chart page
    res.render('chart');
    }
});

});

Any ideas how to achieve this? I want to send my json data extracted from the SQL query and render my page, all at once.

EDIT

On the client side javascript my code is as follows:

function drawHorizontalBar() {

$.getJSON('/charts', function(json) {

    var newJson = json.map(Object.values);


    var options = {
    chart: {
      title: 'Record Count Over time',
      chartArea: {width:'100%'}
    },
    height:400,
    hAxis: {
      title: 'Record Count',
      minValue: 0,
    },
    vAxis: {
      title: 'Date'
    },
    bars: 'horizontal'
  };

    var dataTable = new google.visualization.DataTable();
    dataTable.addColumn('string', 'Date');
    dataTable.addColumn('number', 'Record Count');
    dataTable.addRows(newJson);

    var material = new google.charts.Bar(document.getElementById('test_div'));
    material.draw(dataTable, options);
});

}

If I use the suggested:

res.render('chart', { table: table });

How do I access table in my client side javascript? Any ideas

Answer 1

According to Express 4 docs, you can pass a variable in the render method

// pass a local variable to the view
res.render('chart', { data: table }, function(err, html) {
  // ...
});

https://expressjs.com/en/api.html#res.render

Then you can access your table in client side Jade/Pug using:

#{data.something} // #{table.something}