CODEWITHSUNDEEP
mongodbmongoosemongodb-query
Phil
Phil

Reputation: 3562

Mongoose query using if else possible?

I have this Schema:

const guestSchema = new Schema({
  id: String,
  cart: [
    {
      product: {
        type: mongoose.Schema.ObjectId,
        ref: "products"
      },
      quantity: Number
    }
  ]
});

I have this query:

Guest.findOneAndUpdate(
        { id: req.sessionID },
        {
          $cond: [
            { "cart.product": { $ne: req.body.itemID } },
            { $push: { "cart": { product: req.body.itemID, quantity: 1 } } },
            { $inc: { "cart.quantity": 1 } }
          ]
        },
        { upsert: true, new: true }
      ).exec(function(err, docs) {
        err ? console.log(err) : res.send(docs);
});

Basically, what I'm trying to do is update based on a condition. I tried using $cond, but found out that operator isn't used for querys like I'm doing.

Based on this:

{ $cond: [ <boolean-expression>, <true-case>, <false-case> ] }

I want something similar to the functionality of this operator for my query.

Let's break down my condition:

For my boolean expression: I want to check if req.body.itemID is $ne to any of the values in my cart

If true then: $push the itemID and quantity into the cart

Else (then item already exists): $inc the quantity by 1

Question: How would achieve this result? Do I need to make two seperate querys? I'm trying to avoid doing that if possible

Upvotes: 5

Views: 5230

Answers (2)

Phil
Phil

Reputation: 3562

I went through all their Update Field Operators, and there's probably no way to do this in the way I want.

I wonder why there is no $cond for update operators. Nonetheless, I have the solution to what I wanted the functionality accomplish. Just not in the elegant fashion that I would like it.

Guest.findOneAndUpdate(
        { id: req.sessionID },
        { id: req.sessionID }, //This is here in case need to upsert new guest
        { upsert: true, new: true }
      ).exec(function(err, docs) {
        if (err) {
          console.log(err);
        } else {

          //Find the index of the item in my cart
          //Returns (-1) if not found
          const item = doc.cart.findIndex(
            item => item.product == req.body.itemID
          );

          if (item !== -1) {
            //Item found, so increment quantity by 1
            doc.cart[item].quantity += 1;
          } else {
            //Item not found, so push into cart array
            doc.cart.push({ product: req.body.itemID, quantity: 1 });
          }

          doc.save();
        }
});

Upvotes: 1

Aaron Rumery
Aaron Rumery

Reputation: 562

This type of logic does not belong within the database query. It should happen in the application layer. MongoDB is also very fast at retrieving and updating single records with an index so that should not be a concern.

Please try doing something like this:

try {
  const guest = await Guest.findOne().where({
    id: req.sessionID
  }).exec();
  // your cond logic, and update the object
  await guest.save();
  res.status(200).json(guest);
} catch (error) {
  handleError(res, error.message);
}

Upvotes: 0

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