Executing callback in the incorrect context

I'm facing an issue and can't seem to navigate through it. I am setting up a callback from a third party directive, but the callback is not returning with the correct scope. This means that when it reaches my controller, this refers to some other scope that I can't quite identify, making it unable to access any member variables. How can I switch back to my controller's scope?

<ui-gmap-layer type="HeatmapLayer" onCreated="$ctrl.heatLayerCallback"></ui-gmap-layer>

Component Controller:

heatLayerCallback(heatLayer: google.maps.visualization.HeatmapLayer) {
    this.heatMapLayer = heatLayer;
    // 'this' here does not reference my controller
}

If I modify the callback like so:

<ui-gmap-layer onCreated="$ctrl.heatLayerCallback(layer)"></ui-gmap-layer>

Then the callback executes within the correct scope (i.e. my controller), but unfortunately, the parameter layer is lost ;/

Notes

I am using Typescript, Angular 1.6, and Angular Components

angularjstypescriptangular-google-maps

Answer №1

If you prefer, you have the option to utilize bind in order to connect the callback to the specific context (like your controller) or alternatively, you can save it in a new variable before the callback and then refer to it using that variable within the callback.

For example:

var heatLayerCallback = (function(heatLayer: google.maps.visualization.HeatmapLayer) {
    this.heatMapLayer = heatLayer;
    // Here, 'this' is now the same as the 'this' outside of this scope
}).bind(this); // Connect to 'this' or any other desired context

...or:

var that = this; // Save 'this' or your chosen context
...
heatLayerCallback(heatLayer: google.maps.visualization.HeatmapLayer) {
    that.heatMapLayer = heatLayer;

The exact syntax may vary depending on where your provided code is situated (e.g. determine where "this" represents your intended context, or substitute "this" with another appropriate context).

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