The goal, is to lookup for object field value in user.inCart array, if the value is found, update the object field quntity. Else case push a new object to the array.

I have this code working fine:

       Users.findOneAndUpdate({
       id:req.user.id,
       'inCart.item': req.body.item
   },
   {
       $inc: {'inCart.$.quantity': req.body.quantity}
   }).then(data=>{
       if (data!=null) {
           res.status(200)
       } else{
           Users.findOneAndUpdate({
               id:req.user.id,
           },{
               $push : {inCart:{item:req.body.item, quantity: req.body.quantity} }
           }).then(()=>res.status(200))
       }
   })

}

is there a way to do the same with a single reqest?

CodePudding user response：

Query

• you can do it with pipeline update MongoDB >= 4.2
• find the id
• filter to see if item exists (in code replace the 1 with the item identifier (itemName/code etc))
• if isNewItem => add it to the inCard with quantity 1
• else $map and update the quantity by 1

*instead of filter map, you could do it with 1 reduce also, but concatArrays is slower if you had like inCard>1000 items

Test code here

update({"id":{"$eq":1}},
[{"$set":
  {"isNewItem":
   {"$eq":
    [{"$filter":
      {"input":"$inCard", "cond":{"$eq":["$$this.item", 1]}}},
     []]}}},
 {"$set":
  {"inCard":
   {"$cond":
    ["$isNewItem",
     {"$concatArrays":["$inCard", [{"item":1, "quantinty":1}]]},
     {"$map":
      {"input":"$inCard",
       "in":
       {"$cond":
        [{"$eq":["$$this.item", 1]},
         {"$mergeObjects":
          ["$$this", {"quantity":{"$add":["$$this.quantity", 1]}}]},
         "$$this"]}}}]}}}, {"$unset":["isNewItem"]}])

CodePudding user response：

I hope this will solve your issue within mind the cart default quantity would be 0 or less than 1

Users.findOneAndUpdate({
      id: req.user.id,
      'inCart.item': req.body.item
    }, {
      $set: {
        'inCart.$.quantity': {
          $cond: {
            if: {
              $gte: ["inCart.$.quantity": 1]
            },
            then: {
              $add: ["inCart.$.quantity", req.body.quantity]
            },
            else: req.body.quantity
          }
        }
      }
    })