502 GET请求上有节点，ajax，restful api的错误网关

Question

我在单击应用程序上的按钮时尝试执行mysql查询而不刷新页面。当我点击我的＆＃34;更多信息＆＃34;我在我的Chrome浏览器上收到502坏网关日志按钮。 注意：以下部分代码用于Michael Cheng的YouTube视频。

我的代码：

staticPricing.js

$(function() {
// GET/READ info FROM server
$('#getInfoMats-button').on('click', function () {
    // ajax GET request
    $.ajax({
        url: '/materials',
        contentType: 'application/json',
        success: function (response) {
            console.log(response);
            var tbodyEl = $('#tbodytest');

            tbodyEl.html('');

            response.result.forEach(function (result) {
                tbodyEl.append('\
                    <tr>\
                       <td>' + result.PricePerSheetORFt + '</td> \
                    </tr>\
                    ');
            });
        }
    });
});

pricingTable.js

    // sql handler
    exports.sqlGetMaterialPricing = "SELECT PricePerSheetORFt FROM genericname.info_pricing WHERE 'Key' = ?;";


exports.getMaterial = function(req, res) {
    var weErrored = false;
    var post = {
        PricePerSheetORFt: req.body.PricePerSheetORFt
    };



    mySqlController.connection.query(exports.sqlGetMaterialPricing, post, '1',
        function(err, result, fields){
            if (err) {
                console.log(err.code);
                weErrored = true; // setting the error to true, this is used to display a message on the front end

            }
            res.send(JSON.stringify(result));
        });

}

路线

var pricingTable = require('../controllers/pricingTable');
app.get('/materials', pricingTable.getMaterial);

和

pricingTable.hbs

<script src="staticPricing.js"></script>

<tbody id="tbodytest">
            {{#each data}}
                <tr>
                    <td>{{this.IGNORE}}</td>
                    <td>{{this.IGNORE}}</td>
                    <td>{{this.IGNORE}}</td>
                    <td>
                        <p>
                            <button id="getInfoMats-button" class="btn btn-outline-secondary" data-toggle="collapse" data-target="#collpase{{this.Key}}" aria-expanded="false" aria-controls="collapseExample">
                                More Info
                            </button>
                        </p>
                    </td>

                </tr>

                <tr>
                    <td colspan="4">
                        <div class="collapse" id="collapse{{this.Key}}">
                            <div class="card card-block">
                                <div class="row">
                                    <div class="col">
                                        <p><strong>PricePerSheetORFt:</strong> {{this.PricePerSheetORFt}}</p>
                                    </div>
                                </div>
                            </div>
                        </div>
                    </td>
                </tr>

            {{/each}}
            </tbody>

请不要介意这个。签名，我改变了这个问题。