Purpose

To describe how to set a hookfunction to a connection using the BDE.

Introduction

Sometimes you will need to process the value of a slot before it propagated through a connection. For example, you may need to do some data transformation to fit the target slots expected structure. To aim that you should use  hook function. To declare a hook function, which will be called each time a connection triggers. The hook function will be called with the propagated value and a callback function next, which should be called after the data is processed. A hook function should look as follows:

function (value, next) {
    // Do your data transformation based on value
    var newValue = value * 2;

    // Call next callback with transformed value
    next(newValue);
}

The following sections will show you how to set and use a hook function using the BDE.

An example component

The hook functions are defined for connections between two members. Therefore, we will compose component, we will use the cubx-color-input and the cubx-textarea components to get the following compound: