How can I insert a array of objects into a mysql database

Question

I have a problem where I have an array of objects like this:

 [
  {
    department_id: '6256f8ae6f749617e8167416',
    employee_id: '6253ca0c6f749618a8d022af',
    employee_number: '1234'
  },
  {
    department_id: '6256f8ae6f749617e8167416',
    employee_id_id: '6253ca0c6f749618a8d022af',
    employee_number: '1503'
  }
]

and would like to use node.js and mysql to insert it into a database so I have got this script

Department.assignEmployeetoDepartment = (employees, result) => {
  let employees_array = Object.values(rooms);

  db.query(
    `INSERT INTO department_employee (department_id, employee_id, employee_number) VALUES ?`,
    [employees_array],
    (err, res) => {
      if (err) {
        console.log("error: ", err);
        result(err, null);
        return;
      }

      console.log("success: ", res);
      result(null, res);
    }
  );
};

when I use the code above, I get

INSERT INTO department_employee (department_id, employee_id, employee_number) VALUES '[object Object]', '[object Object]'

which does not work for obvious reasons. I tried to stringify the object and I also tried to use a for loop to iterate over the employees array and it did not work as it says the headers were already sent.

How could I store the array (which can vary in length into the database? Thanks in advance

Answer 1

As per mysql- Escaping query values

Nested arrays are turned into grouped lists (for bulk inserts), eg [['a', 'b'], ['c', 'd']] turns into ('a', 'b'), ('c', 'd')

You probably want to map the values to array, you can't pass array of JSON object to query

  db.query(
    `INSERT INTO department_employee (department_id, employee_id, employee_number) VALUES ?`,
    [employees_array.map(employee => [employee.department_id, employee.employee_id, employee.employee_number])],
    (err, res) => {
      if (err) {
        console.log("error: ", err);
        result(err, null);
        return;
      }

      console.log("success: ", res);
      result(null, res);
    }
  );
};

Answer 2

The solution I'm suggesting for you will serve you safe if you make your data an array of arrays;

const employeesData = [
     [
      '6256f8ae6f749617e8167416',
      '6253ca0c6f749618a8d022af',
      '1234'
    ],
    [
     '6256f8ae6f749617e8167416',
     '6253ca0c6f749618a8d022af',
     '1503'
    ],
  ];

Next, prepare your query like this;

const sql = `INSERT INTO images (department_id, employee_id, employee_number) VALUES?`;

You're now ready to run your query liike below;

    db
  .query(sql, [employeesData])
  .then(rows => {
     res.status(200).json({
       status: "success",
       message:"Data inserted successfully"
     });
   })
   .catch(err => {
     res.status(500).json({
       status: "error",
       error: err.message
     });
  });

You can generate array of values to insert using array's map method like shown below,

employeesData = dataSourceArray.map ( (data) => {
  return [
     department_id,
     employee_id,
     employee_number
];
});

Answer 3

You can't insert an array in a table, an array IS a table