Build a class to create an object with variable key

Question

I want to create an object with variable key with the help of class instance. I have tried by the following code

class ACL {
    constructor(key){
        this[key] = {
            read: false,
            write: false,
            delete: false
        }
    }

    setRoleReadAccess(key, value){
        [key] = {
            read: value,
        }
    }
    setRoleWriteAccess(key, value){
        [key] = {
            write: value,
        }
    }
    setRoleDeleteAccess(value){
        [key] = {
            delete: value,
        }
    }
}

const userACL = new ACL("1234");
userACL.setRoleReadAccess("1234", true);
userACL.setRoleWriteAccess("1234", true);
console.log(userACL);

But i am getting this error UnhandledPromiseRejectionWarning: TypeError: Invalid attempt to destructure non-iterable instance

i am expecting the following console output

ACL {
 "1234": {
    read: true,
    write: true,
    delete: false
  }
}

Can anyone tell me how can resolve this

what is [this.key] in the constructor?

Alan Omar
– Alan Omar

2022-06-07 11:19:37 +00:00
Commented Jun 7, 2022 at 11:19 — Alan Omar
– Alan Omar, Commented Jun 7, 2022 at 11:19
yes i am passing in constructor now

Avinash A
– Avinash A

2022-06-07 11:23:14 +00:00
Commented Jun 7, 2022 at 11:23 — Avinash A
– Avinash A, Commented Jun 7, 2022 at 11:23
change [this.key] to this[key] and tell me what happens

Francisco Santorelli
– Francisco Santorelli

2022-06-07 11:31:23 +00:00
Commented Jun 7, 2022 at 11:31 — Francisco Santorelli
– Francisco Santorelli, Commented Jun 7, 2022 at 11:31
@FranciscoSantorelli getting same error

Avinash A
– Avinash A

2022-06-07 11:39:38 +00:00
Commented Jun 7, 2022 at 11:39 — Avinash A
– Avinash A, Commented Jun 7, 2022 at 11:39

2 revs · Accepted Answer · 2022-06-07 11:27:52Z

3

[this.key] = and [key] = are trying to do iterable destructuring on what follows the =, but you can't do iterable destructuring on plain objects, they aren't iterable.

class ACL {
    constructor(key) {
        this[key] = { // ***
            read: false,
            write: false,
            delete: false
        }
    }

    setRoleReadAccess(key, value){
        this[key] = {   // ***
            read: value,
        }
    }
    setRoleWriteAccess(key, value){
        this[key] = {   // ***
            write: value,
        }
    }
    setRoleDeleteAccess(key, value){ // ** I added a missing `key` parameter here
        this[key] = {   // ***
            delete: value,
        }
    }
}

edited Jun 7, 2022 at 11:27

community wiki

2 revs
T.J. Crowder

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8 Comments

Alan Omar Over a year ago

I guess from his comment he 's passing key through the constructor

T.J. Crowder Over a year ago

@AlanOmar - Sigh, yeah, that wasn't there before. I'll update.

Avinash A Over a year ago

now I am passing key in constructor

T.J. Crowder Over a year ago

@AvinashAnshu - Yeah, I've updated.

Avinash A Over a year ago

@T.J.Crowder I tried again but getting same error class ACL { constructor(key){ this[key] = { read: false, write: false, delete: false } } setRoleReadAccess(key, value){ [key] = { read: value, } } setRoleWriteAccess(key, value){ [key] = { write: value, } } setRoleDeleteAccess(value){ [key] = { delete: value, } } }

|

PsyGik · Accepted Answer · 2022-06-07 12:11:34Z

When you do [key] = {}, you are trying to do a destructuring, which doesn't work because you can't destructure an object that way. It only works on arrays.

What you need is an assignment to this[key].

class ACL {
  constructor(key) {
      this[key] = { 
          read: false,
          write: false,
          delete: false
      }
  }

  setRoleReadAccess(key, value){
      this[key] = {   
          ...this[key],
          read: value,
      }
  }
  setRoleWriteAccess(key, value){
      this[key] = {   
        ...this[key],  
        write: value,
      }
  }
  setRoleDeleteAccess(key, value){ 
      this[key] = {  
        ...this[key],  
        delete: value,
      }
  }
}

const userACL = new ACL("1234");
userACL.setRoleReadAccess("1234", true);
userACL.setRoleWriteAccess("1234", true);
console.log(userACL);

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