如何修复'类型错误无法读取未定义的属性0'？

Question

I can't get row[].column_name in my .hbs file althougth when I console.log(row) it shows the result.

The error is the following:

TypeError: Cannot read property 0 of undefined

router.get('/:id/baiviet', (req, res) => {
  var id = req.params.id;
  var p = baivietModel.allByCat(id);
  var q = chuyenmuc.singel(id); // singel(id) return a promise
  var row;

  q.then(rows => {
    row = rows;
  });

  p.then(rows => {
    for (const cm of res.locals.lcChuyenmuc) {
      if (cm.ID == +id) {
        cm.isActive = true;
      }
    }
    res.render('vwBaiviet/byCat', {
      baiviet: rows,
      CM: row[0]
    });
  }).catch(err => {
    console.log(err);
  });
});

My .hbs file:

{{this.CM.Name}}

Answer 1

TypeError: Cannot read property 0 of undefined

  var row;

Will initialize the row value to be undefined hence you're getting that error.

If you use Promise.all you can resolve two promises and send a value at once.

router.get('/:id/baiviet', (req, res) => {
  var {id} = req.params;

  Promise.all([
    baivietModel.allByCat(id),
    chuyenmuc.singel(id) // singel(id) return a promise
  ]).then(([prows, qrows]) => {

    // ... your other code

    res.render('vwBaiviet/byCat', {
      baiviet: prows,
      CM: qrows[0]
    });
  }).catch(err => {
    console.log(err);
  });

});