只有在nodejs路由器上完成所有事务后，才返回到ajax调用

Question

I am trying to make an ajax call to a node page, which performs some operations to the database, based on the parameters passed in the ajax calls. The issue I am facing is that the control is passed back to the html page(I am using an alert to test the request completion) which initiated the ajax call even before all the DB transactions are completed on the nodejs end. I have added a smaller version of the code for better understanding.

Origin: HTML page
<div id="paramList">
    <form action='import/other' method='POST' style='display:none;' id="h_form">
    <label><input type="checkbox" value="opt1" />Option 1</label>
    <label><input type="checkbox" value="opt2" />Option 2</label>
    <label><input type="checkbox" value="opt3" />Option 3</label>
    <label><input type="checkbox" value="opt4" />Option 4</label>
    <label><input type="checkbox" value="opt5" />Option 5</label>
    </form>
</div>
<button onclick="startValidation()">Submit</button>

Handler: JS
function startValidation() {
    var paramlist = '';
    $("#paramList input[type='checkbox']").each(function() {
        if ($(this).is(":checked")) {
            paramlist += "'" + $(this).val() + "',";
        }
    });
    paramlist = paramlist.substr(0, paramlist.length - 1);

    var req = $.ajax({
        url: '/import/validate',
        type: 'POST',
        data: { paramList: paramlist, fileName: finalName }
    })
    req.done(function(data, status) {
        alert('Data validated successfully. Select Ok to go to validate sheet: ' + status);
        var form = $("#h_form");
        form.submit();
        //redirect to the other page and load data from the latest insert
    });
    req.fail(function(xOptions, textStatus) {
        alert('Error occured!: ' + textStatus);
    });

}

Server side script

NodeJS: Router
router.post('/validate',function(req,res){
    var paramlist = req.body.paramList;
    var fileName = req.body.fileName;
    var cli = modImport.parseFile(fileName,paramlist);
    res.send(cli);
});

//Import module: modImport.js
module.exports.executeQuery = function(strSQL, operationType, tableName, cb, param) {
    logger.log('debug','running query: '+strSQL);

    var request = new sql.Request(connection);
    request.query(strSQL,function(err, recordset) {
        if(err){
            logger.error('ERROR in '+operationType+' ON '+tableName+': '+err);
        }
        logger.info(operationType+' ON '+tableName+' successful!');
        if(cb){
            cb(param);
        }
    });

},

module.exports.parseFile: function(filePath, validateParam){
    sql.connect(config).then(function() {
        var arr = [];
        arr.push(data);arr.push(validateParam);
        arr.push(tName);

        var delQ = "DELETE FROM [Tbl_TempData]";
        util.executeQuery(delQ,'DELETION','[Tbl_TempData]', module.exports.bulkImportIntoTempData, arr);

        console.log("deletion completed");

    }).catch(function(err) {
        logger.error('other error: '+err); 
    });
},

module.exports.bulkImportIntoTempData: function(arr){
    var data = arr[0];
    var validateParam = arr[1];
    var tName = arr[2];

    var bInQ = "INSERT INTO [Tbl_TempData] (field1,field2,field3) VALUES ";
    data.forEach(function(rec, index){
        var keys = Object.keys(rec);
        var kLen = keys.length - 1;

        keys.forEach(function(datum,cursor){                
            bInQ += "('" + datum + "','" + rec[datum] + "','" + tName + ")";
            if(cursor < kLen){
                bInQ += ",";
            }
        });
    });
    module.exports.executeQuery(bInQ,'BULK INSERTION','[Omni_TempSurveyData]',module.exports.processForTempCalc,validateParam);
},

module.exports.processForTempCalc: function(validateParam){
    var strSQL = "DELETE FROM [Tbl_TempCalc]";
    util.executeQuery(strSQL,'DELETION','[Tbl_TempCalc]',module.exports.insertIntoTempCalc,validateParam);
},

module.exports.insertIntoTempCalc: function(validateParam){
    var strSQL = "INSERT INTO .....";
    //some transformations here from other tables
    util.executeQuery(strSQL,'INSERTION','[Tbl_TempCalcData]');


},

module.exports.insertIntoBlankCalc: function(validateParam){
    var strSQL = "INSERT INTO .....";

    util.executeQuery(strSQL,'INSERTION','[Tbl_BlankCalcData]');

    //TODO: return the ajax call
}

After the ajax completion, the user is to be redirected to a page which is loading data from the last inserted table. But since the alert is popped up before final insertion, the redirected page is shown blank to the user. Please suggest how to overcome this scenario.

Answer 1

if i am right the "modImport.parseFile" function does not return anything and just calls "util.executeQuery" in a promise.

so in this line "var cli = modImport.parseFile(fileName,paramlist);" cli is not valued and raises an error;

i think you should send "res.send(cli)" as callback for "modImport.parseFile" as parameter and then send it for "util.executeQuery" or you should change your functions

update: i changed your code this way. so i can not run it but i guess it will works. hope it helps.

router.post('/validate',function(req,res){
    var paramlist = req.body.paramList;
    var fileName = req.body.fileName;

    var GLOBAL.response_function = function(err,data) 
    {
        //here you can do anything with your data or err;
        // like that 

        if (err)
        {
            return res.status(404).send(err.toString());
        }
        else 
        {
            // if your data is json
            return res.status(200).send(JSON.stringify(data));
        }
    };

    modImport.parseFile(fileName,paramlist) ;
});

module.exports.executeQuery = function(strSQL, operationType, tableName, cb, param) {
    logger.log('debug','running query: '+strSQL);

    var request = new sql.Request(connection);
    request.query(strSQL,function(err, recordset) {
        if(err){
            logger.error('ERROR in '+operationType+' ON '+tableName+': '+err);
        }
        logger.info(operationType+' ON '+tableName+' successful!');

        if(cb){

            if (param.is_return_callback)
            {
                cb(err, recordset)
            }
            else 
            {
                cb(param);
            }
        }


    });

},

the point is you send this ",GLOBAL.response_function, {is_return_callback:true}" by last function which should execute query

   module.exports.insertIntoTempCalc: function(validateParam){
        var strSQL = "INSERT INTO .....";
        //some transformations here from other tables

        util.executeQuery(strSQL,'INSERTION','[Tbl_TempCalcData]',GLOBAL.response_function, {is_return_callback:true});
    },

Answer 2

if other functions work fine this will resolve the problem:

NodeJS: Router
    router.post('/validate',function(req,res){
        var paramlist = req.body.paramList;
        var fileName = req.body.fileName;
        var cli = modImport.parseFile(fileName,paramlist,function(){  
          res.send(cli);
        });
    });

    //Import module: modImport.js
    module.exports.executeQuery = function(strSQL, operationType, tableName, cb, param) {
        logger.log('debug','running query: '+strSQL);

        var request = new sql.Request(connection);
        request.query(strSQL,function(err, recordset) {
            if(err){
                logger.error('ERROR in '+operationType+' ON '+tableName+': '+err);
            }
            logger.info(operationType+' ON '+tableName+' successful!');
            if(cb){
                cb(param);
            }
        });

    },

    module.exports.parseFile: function(filePath, validateParam,callback){
        sql.connect(config).then(function() {
            var arr = [];
            arr.push(data);arr.push(validateParam);
            arr.push(tName);

            var delQ = "DELETE FROM [Tbl_TempData]";
            util.executeQuery(delQ,'DELETION','[Tbl_TempData]', module.exports.bulkImportIntoTempData, arr);

            console.log("deletion completed");
            callback()

        }).catch(function(err) {
            logger.error('other error: '+err); 
            callback()
        });
    },

    module.exports.bulkImportIntoTempData: function(arr){
        var data = arr[0];
        var validateParam = arr[1];
        var tName = arr[2];

        var bInQ = "INSERT INTO [Tbl_TempData] (field1,field2,field3) VALUES ";
        data.forEach(function(rec, index){
            var keys = Object.keys(rec);
            var kLen = keys.length - 1;

            keys.forEach(function(datum,cursor){                
                bInQ += "('" + datum + "','" + rec[datum] + "','" + tName + ")";
                if(cursor < kLen){
                    bInQ += ",";
                }
            });
        });
        module.exports.executeQuery(bInQ,'BULK INSERTION','[Omni_TempSurveyData]',module.exports.processForTempCalc,validateParam);
    },

    module.exports.processForTempCalc: function(validateParam){
        var strSQL = "DELETE FROM [Tbl_TempCalc]";
        util.executeQuery(strSQL,'DELETION','[Tbl_TempCalc]',module.exports.insertIntoTempCalc,validateParam);
    },

    module.exports.insertIntoTempCalc: function(validateParam){
        var strSQL = "INSERT INTO .....";
        //some transformations here from other tables
        util.executeQuery(strSQL,'INSERTION','[Tbl_TempCalcData]');


    },

    module.exports.insertIntoBlankCalc: function(validateParam){
        var strSQL = "INSERT INTO .....";

        util.executeQuery(strSQL,'INSERTION','[Tbl_BlankCalcData]');

        //TODO: return the ajax call
    }