Wednesday, August 17, 2016

Angular 1.5 Components: Pass event data to components

I got some trouble finding out how to pass event data from a child component to a parent component.

Here is a quick example to explain the problem:

- Imagine I have a ProductListingComponent. Inside this ProductListingComponent, I have a ProductListComponent that renders a list of ProductListItemComponents. On every ProductListItemComponent I have a “Add to Basket” button. When I click on this button I want to add the selected product to my shopping basket that is managed at the ProductListingComponent level.

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How can I easily pass the selected product up to my parent components? Let’s find out.

Let’s first create the 3 components with their html:

Now I want to add a function to handle the click on the “Add to Basket” button and pass the product to the parent component. The correct way to pass data between child and parent component is through events. So let’s first add an ng-click directive to the button and extend our components to output an event:

Last step and that is the most tricky one is to pass the product information through the event up to the parent controller. The magic is in the html of the ProductListComponent where I create a map of local variable names and values and pass it to the event: on-select="$ctrl.onSelect({product:product})". Angular will recognize the Product property by it’s name and pass it on to the product variable in the onProductSelected function of the parent controller: on-select="$ctrl.onProductSelected(product)".

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