How to retrieve the average value from a PostgreSQL database using a Sequelize ORM with React Node.js bundle.

Mike Muckler
Mike Muckler used Ask the Experts™
on
I am trying to retrieve the average value from a PostgreSQL database using a Sequelize ORM with React on the front end and running Node.js server.  My 'GET' request on the Node side retrieves all of the data from the PostgreSQL database so I know everything is wired up with React using the following code:

module.exports = function (db, app, bodyParser) {


    app.use(bodyParser.json());
    app.use(bodyParser.urlencoded({ extended: false }));

    app.get('/survey_init', function(req, res, next) {
        db.answers.findAll({})
        .then(function (data) {

            res.send(data);
              })
          .catch(function (err) {
            return next(err);
          })
        });
        
    }

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However, when I attempt to run an average on a specific column called 'conf_one' in my PostgreSQL database I get an error.  I will list the modified code (modified from code above) that is throwing the error here:

module.exports = function (db, app, bodyParser) {


    app.use(bodyParser.json());
    app.use(bodyParser.urlencoded({ extended: false }));

    app.get('/survey_init', function(req, res, next) {
        db.answers.findAll({
          attributes: ['conf_one', [models.Sequelize.fn('AVG', models.Sequelize.col('conf_one')), 'conf_one_avg']]
        })
        .then(function (data) {

            res.send(data);
              })
          .catch(function (err) {
            return next(err);
          })
        });
        
    }

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The error that I get with the code is the following error and I do not get the result of an average calculation.

GET http://localhost:3000/survey_init 500 (Internal Server Error)
dispatchXhrRequest @ xhr.js:178
xhrAdapter @ xhr.js:12
dispatchRequest @ dispatchRequest.js:59
Promise.then (async)
request @ Axios.js:51
wrap @ bind.js:9
current_aggs @ current_aggs.js:7
handleClick @ Survey.js:46
callCallback @ react-dom.development.js:100
invokeGuardedCallbackDev @ react-dom.development.js:138
invokeGuardedCallback @ react-dom.development.js:187
invokeGuardedCallbackAndCatchFirstError @ react-dom.development.js:201
executeDispatch @ react-dom.development.js:461
executeDispatchesInOrder @ react-dom.development.js:483
executeDispatchesAndRelease @ react-dom.development.js:581
executeDispatchesAndReleaseTopLevel @ react-dom.development.js:592
forEachAccumulated @ react-dom.development.js:562
runEventsInBatch @ react-dom.development.js:723
runExtractedEventsInBatch @ react-dom.development.js:732
handleTopLevel @ react-dom.development.js:4476
batchedUpdates$1 @ react-dom.development.js:16659
batchedUpdates @ react-dom.development.js:2131
dispatchEvent @ react-dom.development.js:4555
interactiveUpdates$1 @ react-dom.development.js:16714
interactiveUpdates @ react-dom.development.js:2150
dispatchInteractiveEvent @ react-dom.development.js:4532
index.js:2178 Error for getting confidence data Error: Request failed with status code 500
    at createError (createError.js:16)
    at settle (settle.js:18)
    at XMLHttpRequest.handleLoad (xhr.js:77)

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Any suggestions on how to retrieve the average value from a PostgreSQL database using a Sequelize ORM with React on the front end and running Node.js server with the above error?
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Kyle SantosSoftware Test Analyst I at Dassault Systemes

Commented:
Hi,

I am here to help you with your open question.  Do you still need help?  I have the ability to alert more experts if you still need help.

If you solved the problem on your own, would you please post the solution here in case others have the same problem?

If you need me to delete this question just say "Delete."

Thank you for using Experts Exchange.

Regards,

Kyle Santos
Customer Relations

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