CODEWITHSUNDEEP
javascriptarraysnode.jsexpressdictionary
iLiA
iLiA

Reputation: 3153

Mapping array inside async function causes error

Hello i have array of objects validation inside my async function (router.post()) and i need to map it before validating and this is how I do it

ingredients.map(({ingredient,quantity})=>{
   if(ingredient.trim().length < 1 || quantity.length < 1){
     return res.status(409).send({
       message: ''
     })
   }
})

and after this i send 200 status code to client side (ReactJS) but it causes error

Can't set headers after they are sent

i do not know what is problem with this.

before this block of code i have only if statements to validate other inputs and when i commented this block of code the if statements worked. So what is problem with this?

P.S: I stringified array before sending the server and then parsed of course

EDIT: it does not causes errors when everything is ok and ingredient or quanitity is not empty

Upvotes: 0

Views: 56

Answers (1)

antonku
antonku

Reputation: 7675

The issue occurs because res.send is being called multiple times.

If your intention is to respond with 409 status code if at least one of ingredients is invalid, you can check if there is at least one invalid item and respond with 409 if it's there:

const hasInvalidIngredient = ingredients.some(
  ({ingredient,quantity}) => ingredient.trim().length == 0 || quantity.length == 0
)

if (hasInvalidIngredient) {
  return res.status(409).send({
    message: ''
  })
}

Upvotes: 2

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