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Extension of a form method - Chain of command - D365 F&O - X++ Code

Chain of command is an option that helps you enhance the functionality of a form method. This option is applicable for standard methods and custom methods of the form.

You can use the following code pattern if you need to extend the init() method of the form:

[ExtensionOf(formStr(Currency))]
final class CurrencyForm_Extension
{
    public void init()
    {
        //code
        next init();
        //code
    }
}

In X++, the ExtensionOf keyword is used to create a class extension that extends the functionality of an existing class. In this case, the CurrencyForm_Extension class extends the Currency form class, as specified by the formStr(Currency) function call.

The init() method is a built-in X++ method that is called when the form is initialized. The next init() statement in the init() method is used to call the init() method of the parent class, which in this case is the Currency form class.

By using next init() to call the parent class's init() method, any initialization code in the parent class is executed before the initialization code in the CurrencyForm_Extension class. This ensures that any necessary initialization tasks are completed before the extension's code is executed.

Here's an example of how you might use ExtensionOf and next init() to extend the functionality of the Currency form class:

[ExtensionOf(formStr(Currency))]
final class CurrencyForm_Extension
{
    public void init()
    {
        // Call the parent class's init() method first
        next init();

        // Add custom initialization code here
        info("Currency form has been initialized.");
    }
}

In this example, we define the CurrencyForm_Extension class as an extension of the Currency form class. In the init() method, we call the parent class's init() method using next init(), and then we add our own custom initialization code, which simply displays an information message.

By using class extensions and the next init() statement, we can easily extend the functionality of existing X++ classes, while still ensuring that any necessary initialization tasks are completed correctly.

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