I am creating a component which handles watch and edit permissions. The data structure I use to hold the permissions looks like this:
const input = [{
isAllowed: true,
permissionType: "watch",
userId: 14
},
{
isAllowed: false,
permissionType: "edit",
userId: 14
},
{
isAllowed: true,
permissionType: "edit",
userId: 24
},
{
isAllowed: false,
permissionType: "edit",
userId: 34
},
{
isAllowed: false,
permissionType: "watch",
userId: 44
},
{
isAllowed: false,
permissionType: "edit",
userId: 44
}
]
At first, I just wanted to get a list of all users with any permissions given at all, so I would use
let managers = _.flatMap(props.settings.managerPermissions, (p) => p.userId);
managers = [...new Set(managers)];
So this would leave me with managers = [14,24,34,44], but I need to edit this flatmap in a way that I would not get back the id of a manager which has no permissions at all, even if they were added to the list already, so in this case the return value of the new flatmap should be managers = [14,24]. (ofcourse flatMap is not a must here and if there's a better way to do it I would be happy to see it)
You only need flatMap when you when the result of map would an array of arrays, and you want a flat array.
In this case filter the array by isAllowed and then map to userId:
const arr = [{"isAllowed":true,"permissionType":"watch","userId":14},{"isAllowed":false,"permissionType":"edit","userId":14},{"isAllowed":true,"permissionType":"edit","userId":24},{"isAllowed":false,"permissionType":"edit","userId":34},{"isAllowed":false,"permissionType":"watch","userId":44},{"isAllowed":false,"permissionType":"edit","userId":44}]
const managers = [...new Set(
arr
.filter(o => o.isAllowed)
.map(o => o.userId)
)]
console.log(managers)However, you actually use Array.flatMap() (or lodash equivalent) to map and filter at the same time. It's less idiomatic the map/filter combo, and I'm not sure about the performance, so I don't use it myself. The idea is to return an empty array for items that you don't want:
const arr = [{"isAllowed":true,"permissionType":"watch","userId":14},{"isAllowed":false,"permissionType":"edit","userId":14},{"isAllowed":true,"permissionType":"edit","userId":24},{"isAllowed":false,"permissionType":"edit","userId":34},{"isAllowed":false,"permissionType":"watch","userId":44},{"isAllowed":false,"permissionType":"edit","userId":44}]
const managers = [...new Set(
arr.flatMap(o => o.isAllowed ? o.userId : [])
)]
console.log(managers)You should be able to just filter out the isAllowed=false and then do the same - although flatMap seems to be useless (as there is no nesting of arrays) - just use map
const input = [
{isAllowed: true,
permissionType: "watch",
userId : 14
},
{isAllowed: false,
permissionType: "edit",
userId : 14
},
{isAllowed: true,
permissionType: "edit",
userId : 24
},
{isAllowed: false,
permissionType: "edit",
userId : 34
},
{isAllowed: false,
permissionType: "watch",
userId : 44
},
{isAllowed: false,
permissionType: "edit",
userId : 44
}]
const managers = [...new Set(input.filter(x => x.isAllowed).map(x => x.userId))];
console.log(managers);