CODEWITHSUNDEEP
typescriptthis
user3236751
user3236751

Reputation:

self = this but cannot access self.function within a callback

I have the following block of code to store the correct reference to this. I am using Mongoose for Models.Image.

class some {
    public one() {
        var self = this;
        this.another(); //edited: this.another() is not a function
        Models.Image.findById(id).then(function(data) {
            self.another(); //self.another is not a function
            ....
        });
    }
    public another() {
        ....
    }
}

The linter is showing self to be this but when I execute it, gives me error. What is happening here? How to solve it?

The class is a route handler bound to express routes.

I would like to add more. Calling this.another() within the one() (not callback) is still giving me is not a function error. Somehow, this is not referencing the class. What may be the problem?

Upvotes: 0

Views: 5440

Answers (2)

Marco V
Marco V

Reputation: 2623

another() is expected to be within public one() :

class some {
    public one() {
        var self = this;
        Models.Image.findById(id).then(function(data) {
            self.another(); //self.another is not a function

            ....
        });
    }
    public another() {
        ....
    }
}

Maybe better like this:

class some {
    public one() {
        var self = this;
        Models.Image.findById(id).then(function(data) {
            self.another(); //self.another is not a function
            ....
        });
        another() {
            ....
        }
    }
}

Upvotes: -3

Paleo
Paleo

Reputation: 23692

Edited: The class is a route handler bound to express routes.

Probably the problem is here.

Because of how the method one is called, this is not bound to an instance of the class some. The issue is not about the callback. At the first line of one, this already has a wrong value:

var self = this; // self has a wrong value because this has a wrong value

Upvotes: 4

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