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Thursday, September 28, 2017

Development Tutorial: Extensibility: Adding a table display/edit method and showing it on a form in PU10

One of the super common tasks for an application developer working to address customer requirements is adding display methods showing some additional customer-specific information on existing forms.

Usually you would overlayer the corresponding table and form and insert the missing method. Overlayering is not an option soon, however it is possible to do the same using only Extensions.

As an example, let us add a new display method showing the internal product name for a selected product - we'll compose it by appending some text to the product search name.

Step 1 - Create a table extension and add a new display method to it - Option 1

As you know, there are two ways to create extension classes now, so let's see both ways in action.
Here we'll look at the "old" way, where we create an actual extension class (as in .NET), so it must be static, and the display method must be static as well, and take the record as the first argument.

Here's how it looks for my example:

/// Extension class for EcoResProduct table.
public static class MyPU10_EcoResProductTable_Extension
    public static display Name myInternalProductName(EcoResProduct _ecoResProduct)
        return 'IntName: ' + strReplace(_ecoResProduct.SearchName, ' ', '');

As you can see, we can define the above method and it will compile even though normally declaring a static display method is not allowed by the compiler.
We can also decorate the method with attribute, like I have done here by applying the display method caching attribute.
The logic of the method is not really important - you'd have your fields used here, most probably, but for the sake of the example I just use SearchName field.

Step 2 - Create a table extension and add a new display method to it - Option 2

So, another "new" way to extend a table is through an augmentation class, using the ExtensionOf attribute. This is shown below for my example:

/// Extension class for EcoResProduct table.
final class MyPU10_EcoResProductExtensionOfTable_Extension
    public static display Name myInternalProductName(EcoResProduct _ecoResProduct)
        return "Alt: " + _ecoResProduct.SearchName;

As you can see, this again is a static method - declaring it as an instance method will compile and would allow you to reference the record through this, but you will not be able to use it as a display method on the form as of today.
The method also needs to take the record as the argument.
It, of course, can also be decorated with the SysClientCacheDataMethod attribute, as in the first example.

Step 3 - Add the methods to a form through extension

Note - Limitation

You cannot as of today add the newly created display methods to a field group on the table. It will compile, but the control will not show up on the form if you add the field group to it.

First off, we'll need to create an extension of the EcoResProductDetails form in the desired model.
Then we'll add a new tab page to it and place two new String controls into it.

Now, the trick is with how to specify the display method name in Properties.

See the example below:

Specify properties for form string control to bind it to a table data method
As you can see, the trick is to specify the full name, including the class name and the method name with the static method delimiter in the format:

<class name>::<static method name>

This is only supported for table methods, so you won't be able to do the same for a Form Data Source, for example.


Here's how our new awesome display methods look at run-time:

Additional information shown through display methods on Product details form

Download the project

You can download it from my OneDrive here.

What's next

In an upcoming platform update we hope to provide a much more intuitive way of adding display methods, however the above approach will keep being supported.
Stay tuned for an update!

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