Use switch statement on mongodb query

help
#1

Hi, I was wondering if this

    if(Worlds_Items.findOne({_id:FlowRouter.getParam('item'), itemSlot: "head"})) {
      return "Head";
    }
    else if(Worlds_Items.findOne({_id:FlowRouter.getParam('item'), itemSlot: "torso"})) {
      return "Torso";
    }
    else if(Worlds_Items.findOne({_id:FlowRouter.getParam('item'), itemSlot: "hands"})) {
      return "Hands";
    }
    else if(Worlds_Items.findOne({_id:FlowRouter.getParam('item'), itemSlot: "legs"})) {
      return "Legs";
    }
    else if(Worlds_Items.findOne({_id:FlowRouter.getParam('item'), itemSlot: "feet"})) {
      return "Feet";
    }

could be converted to a swtich-statement? I read that a lot of if else-statements should be avoided if possible. But since those queries only seem to give out booleans, it seems to be tricky at best. But I was wondering if someone has any solution to this?

many thanks.

#2

if else statements are perfectly fine,

the problem in your code is that it is not DRY (DRY - don’t repeat yourself)

you could do:

const hasItemSlot = (itemSlot) => Worlds_Items.findOne({_id:FlowRouter.getParam('item'), itemSlot}))

// and then

if(hasItemSlot("head")) return "Head"
if(hasItemSlot("torso")) return "Torso"
etc.

but its a bit weird anyway, because Worlds_Items.findOne({_id:FlowRouter.getParam('item')}) will return the same object in every case. its cleaner if you do

const theItem = Worlds_Items.findOne({_id:FlowRouter.getParam('item')})
if(theItem.itemSlot === "head") return "Head"
// etc.

and if you could avoid returning “Head” in uppercase when the value is “head” (lowercase), you could just do

return Worlds_Items.findOne({_id:FlowRouter.getParam('item')})?.itemSlot
4 Likes
#3 

const { itemSlot } = Worlds_Items.findOne({ _id:FlowRouter.getParam('item'), itemSlot: {$in: ['head', 'torso', 'hands', 'legs', 'feet' ] } }, { fields: { itemSlot: 1 } })

Also ensure an index for itemSlot on that collection

3 Likes
#4

Amazing, thank you guys!

#5

@paulishca _id field has an unique index, so there is only one doc in the search result. Why we need to create the itemSlot index?

#6

You are 100% right. In this case you don’t even need the second part of the query, just perhaps the “fields”.

#7

Also, if it runs on client side:

Minimongo doesn’t currently have indexes. It’s rare for this to be an issue, since it’s unusual for a client to have enough data that an index is worthwhile.