I have been facing some problem while updating the data in the db using mongoose, Therefore thanks in advance for the help.

I have been sending some data from a dynamic form that contains different set of fields each time... but when i update the array in the db it changes those fields.

This was my controller function earlier:-

exports.savePageContent = (req, res, next) => {
    const id = req.body.dest;  // getting page data document id
    delete req.body.dest;
    var arr = [];

    // When we are returning the same page each time after we submit the data for the particuklar section form then how are we supposed to redirect the user to next page once he is done doing all 

    var fieldKeys = Object.keys(req.body);
    for(let i = 0; i < fieldKeys.length; i++)
    {
        arr.push({fieldRef : fieldKeys[i], fieldValue : req.body[fieldKeys[i]]});
    }

    pageDataModel.findByIdAndUpdate(id, {pageData : arr}).exec(function(err, result) {
        if(err){
            console.log(err);
        }
        else { 
            console.log("data is inserted");
            req.flash('message', "Data Saved Successfully");
            
        }
    })

} 

I also tried a few updates and then moved to this portion

This is my new controller function :

exports.savePageContent = (req, res, next) => {
    const pageid = req.body.dest;  // getting page data document id
    delete req.body.dest;

    var fieldRefData = "";
    var fieldValueData = "";

    var fieldKeys = Object.keys(req.body);
    for(let i = 0; i < fieldKeys.length; i++)
    {
        fieldRefData = fieldKeys[i];
        fieldValueData = req.body[fieldKeys[i]];

       try{

        pageDataModel.update({id : pageid, "pageData.fieldRef" : fieldRefData}, {$set : {"pageData.$.fieldValue" : fieldValueData }}, {upsert : true}).exec(function(err, result) {
            if(err){
                console.log(err);
            }
            else { 
                console.log("data is inserted", result);
            }
        });

        req.flash('message', "Data Saved Successfully");

       }catch(e){
        console.log(e);
        req.flash('message', "error Occurred updating Data ");

       }
    }

    

}  

To elaborate the case for better understanding:-

This is the data that comes first time in the body

[
  { fieldRef: 'sec1.1.h1', fieldValue: 'this is the field value 1' },
  { fieldRef: 'sec1.1.p', fieldValue: 'this is the field value 1' },
  { fieldRef: 'sec1.1.a', fieldValue: 'this is the field value 1' },
  { fieldRef: 'sec1.2.h2', fieldValue: 'this is the field value 1' }
]

and This is the data that comes the second time :-

[
  { fieldRef: 'sec2.1.h1', fieldValue: 'this the field value 2' },
  { fieldRef: 'sec2.1.p', fieldValue: 'this the field value 2' },
  { fieldRef: 'sec2.1.a', fieldValue: 'this the field value 2' },
  { fieldRef: 'sec2.2.h1', fieldValue: 'this the field value 2' }
]

when i want both the data's in the db but when i send one the second data the first one gets updated to the second one and vice versa..

this is the db images of the scenario

this is the data in the document on the first operation

this is the data in the document on the second operation

i am not able to keep and update them both... so please help me ...

This is the error that I am getting most of the time which says that the query is wrong

MongoServerError: The positional operator did not find the match needed from the query.
    at /home/pushkar/Desktop/NodejsWebApp1/node_modules/mongodb/lib/operations/update.js:80:33
    at /home/pushkar/Desktop/NodejsWebApp1/node_modules/mongodb/lib/cmap/connection_pool.js:272:25
    at handleOperationResult (/home/pushkar/Desktop/NodejsWebApp1/node_modules/mongodb/lib/sdam/server.js:370:9)
    at MessageStream.messageHandler (/home/pushkar/Desktop/NodejsWebApp1/node_modules/mongodb/lib/cmap/connection.js:479:9)
    at MessageStream.emit (events.js:400:28)
    at processIncomingData (/home/pushkar/Desktop/NodejsWebApp1/node_modules/mongodb/lib/cmap/message_stream.js:108:16)
    at MessageStream._write (/home/pushkar/Desktop/NodejsWebApp1/node_modules/mongodb/lib/cmap/message_stream.js:28:9)
    at writeOrBuffer (internal/streams/writable.js:358:12)
    at MessageStream.Writable.write (internal/streams/writable.js:303:10)
    at Socket.ondata (internal/streams/readable.js:731:22) {
  index: 0,
  code: 2
}

Also if I was unable to make my scenario clear please leave a comment and I will try to explain it more clearly.. thanks In Advance