Uncaught TypeError: Cannot read property 'getSMS' of null

Question

Below code is a cordova android sms acess permission plugin code. and it is working fine.

inside that i am trying to call my this.getSMS() function it is throughing error

setTimeout(() => {
      this.holders.dissmissLoadingCustom();
      platform.ready().then(() => { 

      var permissions = cordova.plugins.permissions;

        permissions.hasPermission(permissions.READ_SMS, checkPermissionCallback, null);

        function checkPermissionCallback(status) {
          if(!status.hasPermission) {
            var errorCallback = () => {
              console.log("invoking the errorCallback");
              alert('READ_SMS permission is not turned on');
            }

            permissions.requestPermission(
              permissions.READ_SMS,
              (status) => {
                console.log("invoking status");

              if(!status.hasPermission) {
                console.log("invoke !status.hasPermission");
                errorCallback();
              }
              else{
                console.log("invoking else part !status.hasPermission");
                this.getSMS();//this line through error
              }
            },
            errorCallback);
          }
        }

      });

    }, 10000);

if the user tap allow then i am trying to call my this.getSMS() as you can see in the above code. if user deny then i am just getting error callback.

i dont know what i am doing wrong.

This might help you out. http://stackoverflow.com/questions/3127429/how-does-the-this-keyword-work — Prajwal, Feb 01 '17 at 04:42
@Prajwal i am trying to do as below answer but i am not able to slove the issue if you have any idea please let me know — Mohan Gopi, Feb 01 '17 at 07:09

Suraj Rao · Accepted Answer · 2017-02-01T10:22:19.500

0

You have defined checkPermissionCallback as a regular function. The this keyword points to that function and not the actual class in which it is defined.

setTimeout(() => {
      this.holders.dissmissLoadingCustom();
      platform.ready().then(() => { 

      var permissions = cordova.plugins.permissions;

        permissions.hasPermission(permissions.READ_SMS, (status)=>checkPermissionCallback(status), null);//use arrow to call

        function checkPermissionCallback(status) {
          if(!status.hasPermission) {
            var errorCallback = () => {
              console.log("invoking the errorCallback");
              alert('READ_SMS permission is not turned on');
            }

            permissions.requestPermission(
              permissions.READ_SMS,
              (status) => {
                console.log("invoking status");

              if(!status.hasPermission) {
                console.log("invoke !status.hasPermission");
                errorCallback();
              }
              else{
                console.log("invoking else part !status.hasPermission");
                this.getSMS();//this line through error
              }
            },
            errorCallback);
          }
        }

      });

    }, 10000);

Or you can save this to another variable before the function definition or use bind.

edited Feb 01 '17 at 10:22

answered Feb 01 '17 at 04:51

Suraj Rao

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after trying the updated one i am not invoking the setTimeout itself any idea – Mohan Gopi Feb 01 '17 at 10:11
use the other way then set `self=this` before the function definition – Suraj Rao Feb 01 '17 at 10:13
on trying with your code `permissions.hasPermission(permissions.READ_SMS, checkPermissionCallback, null); ` this piece of line is not exicuting – Mohan Gopi Feb 01 '17 at 10:17
using `self` or arrow? – Suraj Rao Feb 01 '17 at 10:18
using arrow i am not able to invoke self i have not tried yet – Mohan Gopi Feb 01 '17 at 10:19
wait have a different idea.try this – Suraj Rao Feb 01 '17 at 10:20
Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/134572/discussion-between-mohan-gopi-and-suraj). – Mohan Gopi Feb 01 '17 at 10:31

Uncaught TypeError: Cannot read property 'getSMS' of null

1 Answers1