JS: Compare strings of an array with object fields

Question

There is an object, which represents the role of an user:

const user = {
  isEditor: false,
  isAdmin: true,
  isTranslator: false
}

I need to pass some elements to a function an check if any of this role has a true value in the user object.

result = hasPermission(user, ['editor', 'admin']) // true
result = hasPermission(user, ['editor', 'translator']) // false

I've some problems with that, as the roles are named a bit differently. I thought also about using _.some() as I need to check for only one true value.

function hasPermission (user, roles) {
  roles.forEach(role => {
    user[role] // is not working as user keys named differently
  })
}

Are you forced to give different names to your keys? It would be really simpler and not that uglier. — sjahan
– sjahan, Commented Jan 25, 2018 at 7:39
@sjahan If it is really much more easy, I could change the role array string names... Not the object keys. — user3142695
– user3142695, Commented Jan 25, 2018 at 7:43
return user["is" + "admin".slice(0,1).toUpperCase() + "admin".slice(1)]; — Salman Arshad
– Salman Arshad, Commented Jan 25, 2018 at 7:43
@user3142695 if the syntax always stay the same, it's not a very big problem, check my solution ;) — sjahan
– sjahan, Commented Jan 25, 2018 at 7:53

MKougiouris · Accepted Answer · 2018-01-25 07:57:41Z

3

What you are doing is not the proper way to think about it.

A users role are not individual properties, rather a collection of roles. So your user object should be model like

const MyUser = {
  roles: ["Admin","Editor"]
}

So then you can check if a user has a given role by working with a function like so :

function UserHasAnyRole(user,roleKeys)
{
    if(user && user.roles && roleKeys && roleKeys.length)
    {
        return user.roles.filter(function(r){
            return roleKeys.filter(function(k){ return k == r;}).length>0; 
        }).length > 0;

    }       
    return false;    
}

var neededRoles = ["Admin","Translator"];

if(UserHasAnyRole(MyUser,neededRoles))
{
// do stuff
}

This way of thinking about it scales much better, as individual properties is not a sustainable way in the long term

EDIT: to account for arrray of input roles. This is not tested tho, so there might be some syntax errors in there, but you get the idea...

edited Jan 25, 2018 at 7:57

answered Jan 25, 2018 at 7:45

MKougiouris

2,8711 gold badge18 silver badges20 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

user3142695 Over a year ago

That's a very good point. Thanks for that. But if I change the structure like you recommend, I still have the input of multpile roleKeys, which I want to check if any is matching for the user.

MKougiouris Over a year ago

Please review the answer, i forgot to account for the multiple inputs

Marko Bjelac Over a year ago

@MKougiouris - here are some code improvements: 1) Export the string literals as constants in a separate "roles.sj" module e.g. export const ADMIN = "Admin";; 2) swap if logic for readability i.e. if(!user || !user.roles || !roleKeys || !roleKeys.length) { return false; } ...; 3) Simplify Array functions & put in lambda shorthand (the author tagged this with ES6): return user.roles.find(role => roleKeys.find(roleKey => role === roleKey));

MKougiouris Over a year ago

Indeed, good points all of them, maybe with the exception of the 'export' just because i am not familiar enough with it yet and i would probably not use it in a correct way

sjahan · Accepted Answer · 2018-01-25 08:13:40Z

1

Here is a solution the closest to your situation, without changing the shape of your objects and functions.

You can actually use some like this, it is quite simple:

const user = {
  isEditor: false,
  isAdmin: true,
  isTranslator: false
};

function hasPermission (user, roles) {
  return roles.some(role => user["is" + role[0].toUpperCase() + role.substring(1)]);
}

console.log(hasPermission(user, ['editor', 'admin']));
console.log(hasPermission(user, ['editor', 'translator']));

Hoping this will help you!

edited Jan 25, 2018 at 8:13

answered Jan 25, 2018 at 7:44

sjahan

5,9804 gold badges24 silver badges45 bronze badges

Comments

guest271314 · Accepted Answer · 2018-01-25 08:01:32Z

You can use the same property names, Object.entries() to get an array of property, values pairs of the object and Array.prototype.some() and Array.prototype.includes() to check if the values match

const user = {
  isEditor: false,
  isAdmin: true,
  isTranslator: false
}

const hasPermission = (o, keys) =>
  Object.entries(o).some(([key, prop]) => prop && keys.includes(key));

let result = hasPermission(user, ["isEditor", "isAdmin"]);

console.log(result);

result = hasPermission(user, ["isEditor", "isTranslator"]);

console.log(result);

Jecfish · Accepted Answer · 2018-01-25 12:16:15Z

Here is yet another solution.

const user = {
  isEditor: false,
  isAdmin: true,
  isTranslator: false
};

function hasPermission (user, roles) {
  const userRoles = Object
                      .entries(user)
                      .filter(([_, val]) => val)
                      .map(([key, _]) => key.replace('is', '').toLowerCase());
                      
  return roles.some(x => userRoles.includes(x));
  
}

console.log(hasPermission(user, ['editor', 'admin']));
console.log(hasPermission(user, ['editor', 'translator']));

Collectives™ on Stack Overflow

JS: Compare strings of an array with object fields

4 Answers 4

4 Comments

Comments

Comments

Comments

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

4 Comments

Comments

Comments

Comments

Related