I have two tables A and B. The scenario is that I run an array over a loop to use those entries in a findOne query on table A before inserting into table B. Even if one item from the array does not exist in table A the operation should fail. What I have now is as follows

var idList = [1,2,3,4,5];
for (i=0; i<idList.length; i  ){
  await A.findOne({ where: { id : i }}).then((product) => {
    if(!product){
      notValidItem.push(i);
    }
  });
  if (notValidItem.length > 0){
    return res.status(400).send({ message : 'Invalid Operation' });
  }
  else{
    next();
    //going ahead with inserting into table B
  }
}

The above method works for sure... but do we have a more lamda or a function oriented implementation instead of the loop in the above code? Thanks in advance for any help.

CodePudding user response：

Since ive got an advantage that the array items and items from database are going to be unique the following method worked for me

var idList = [1,2,3,4,5];
A.findAll({ where: { id : { [Op.in] : idList }}}).then((foundItems) => {
  foundItemsArray = foundItems.map((x) =>  x.id);
  diffence = idList.filter(x => !foundItemsArray.includes(x));
  if(diffence.length > 0){
    //failure here              
  }
  else{
    next();
  }
})

CodePudding user response：

One solution with Promises would be to use Promise.all() . If any of those Promises fail, you'll get an Error.

try {
    let idList = [1,2,3,4,5];
    let promisesArray = [];
    for (i=0; i<idList.length; i  ){
        promisesArray.push(A.findOne({ where: { id : i }}))
    }
    await Promise.all(promisesChangeMenuOrder);
    next();
} catch (error) {
    console.log(error) // don't console.log errors in production
    return res.status(400).send({ message : 'Invalid Operation' });
}

Next solution would be:

let rows = A.findAll({
    where: {
        id: [1,2,3,4,5]
    }
})

And now check if length is what it should be and if non of those values is null. This is much better solution I think...