CALLBACK ERROR: TypeError: Cannot read property 'rows' of undefined

Question

I'm adding a pagination in my product list. But I kept having error:

console.log(data.rows);
                   ^

Here's my js file that's query-ing in my database:

list: (client, filter, callback) => {
const productListQuery = `
SELECT * 
FROM products 
ORDER BY id
`;
client.query(productListQuery, (req, result)=>{
  console.log(result.rows);
  callback(result.rows);
});

Here's my router.get in my server.js:

app.get('/products', function (req, res, next) {
  Product.list(client, {limit: 8}, {offset: (req.query.p - 1) * 8}, {
  }, function (products) {
    res.render('/client/product-list', {
      products: products,
      title: 'Products',
      pagination: {
        page: req.query.p || 1,
        limit: 8,
        n: req.query.p || 1
      }
    });
  });
});

Please add your code as content to the question, not as image links. — Paul
– Paul, Commented Oct 1, 2018 at 18:13

NAVIN · Accepted Answer · 2018-10-01 17:44:15Z

2

That just simply means your data is undefined and in JavaScript undefined objects don't have any property or value.

Would recommend you to go though JavaScript Documentation before using it.

When you called your database, there was an error in response and since you didn't handled response correctly thus getting this error.

To understand different between undefined and other object values:

let a;
let b = 22;
let c = null;
let d = {
    'a': 22,
    'b': [4,5,6]
};

console.log(a);  // undefined
console.log(a.b);  // TypeError: Cannot read property 'b' of undefined
console.log(b);  // 22
console.log(b.c);  // undefined
console.log(c);  // null
console.log(d.a);  // 22
console.log(d.b);  // [4,5,6]
console.log(e);  // ReferenceError: e is not defined

edited Oct 1, 2018 at 17:44

answered Oct 1, 2018 at 17:32

NAVIN

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