Cannot read property 'first name' of undefined nodejs

Question

const con = require('./../connection');
 exports.getProfile = async function(req,res){

        var user_id    = req.session.user_id;
        var userList   = '';
        var id         = req.params.id ? req.params.id  : '';
        if(!id)
        {
          id = user_id;
        }
        await con.query('select * from users where id = ?',[id],function(error,results,fields){

            res.render('profile',{
              userResult: results[0],
            });
    });
};

<input type="text" name="f_name" data-required="1" value="<%= userResult.first_name %>" class="form-control">

getting correct response on web but getting error in console Cannot read property 'first name' of undefined nodejs

Nico · Accepted Answer · 2019-07-31 12:09:06Z

1

I think you have a synchronization issue there.

You're trying to access userResult before the function callback ends.

I don't know what you're trying to accomplish there but the value you're trying to access will be available here:

 await con.query('select * from users where id = ?',[id],function(error,results,fields){
           // HERE YOU CAN ACCESS TO results[0]

            res.render('profile',{
              userResult: results[0],
            });
  });

answered Jul 31, 2019 at 12:09

Nico

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5 Comments

Sam Over a year ago

I am getting error in EJS file. I think value="<%= userResult.first_name %>" is creating problem does above code solve this issue ?

Nico Over a year ago

Hey @Sam, the code above serve as example as where you can access your results[] without further complexity. As far as I can understand here you're trying to access "userResult.first_name" right? if that's the case you can access that value where I mentioned using results[0].first_name

Sam Over a year ago

Yes it does output when we do console.log(result[0].first_name) but it does work for me when i apply this in ejs file <% if (typeof userResult == 'object' && userResult) { %>

Sam Over a year ago

even i don't understand you only mentioned await not async ?

Nico Over a year ago

I only quoted that part of your code to serve as an example. My intention was to point out that you can access the required data inside the mentioned callback

Terry Lennox · Accepted Answer · 2019-07-31 12:15:12Z

If you wish to access the data outside of the module you'll need to do something like so:

exports.getProfile = async function(req,res){

    var user_id    = req.session.user_id;
    var userList   = '';
    var id         = req.params.id ? req.params.id  : '';
    if(!id)
    {
        id = user_id;
    }

    return new Promise((resolve, reject) => {
        con.query('select * from users where id = ?', [id], function(error, results, fields) {
            if (error) {
                reject(error);
            } else {
                console.log("First name: ", results[0].first_name);
                res.render('profile',{
                    userResult: results[0],
                });
                resolve(results[0]);
            }
        });
    })

};

And then in your importing script:

const { getProfile } = require('./get-profile');

async function testGetProfile() {
    let profile = await getProfile(req, res);
    console.log("Profile: First name: ", profile.first_name);
}

// Pull req, res from relevant route..
testGetProfile(req, res);

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