• Overview
• The Field Library
  • Retrieving Configurations
  • Retrieving Configuration Groups
  • Defining Your Own Configurations & Configuration Groups
    • Defining a FieldLibraryConfiguration
    • Defining a FieldLibraryConfigurationGroup
• Automatic Field Replacement Using the '#' Pseudo-Type
• Address Forms
  • Using the formly-address-form Component
  • Creating a New Country Specific Form
• Standard Reusable Form Configurations
• Further References

Overview

Formly naturally facilitates the reuse of forms through its configuration-based, typescript-first approach.
In the Intershop PWA, there are a number of ways to enhance this reusability and provide developers with the ability to centrally define common form field configurations that can be used throughout the app.
This article showcases the different ways this can be done.

The Field Library

To enable working with reusable form configurations, the FieldLibrary is an integral part of the PWA.
Imagine every configuration object to be a book in this library.
It can be injected anywhere you need to work with formly and provides a simple interface with which to retrieve standard FormlyFieldConfigs.

Retrieving Configurations

To retrieve a predefined FormlyFieldConfig, use the getConfiguration method.
A basic example could look like this:

constructor(private fieldLibrary: FieldLibrary){}
...

this.fields = [
  this.fieldLibrary.getConfiguration('firstName'),
  this.fieldLibrary.getConfiguration('lastName')
]

To use a predefined configuration but modify some properties, the getConfiguration method also takes an optional override argument.
Use it to define any changes you want to make to the configuration.
The properties defined in override will be deeply merged into the standard configuration, overwriting duplicate properties but not affecting others.

For example, you can use the standard firstName field but change the label like this:

this.fieldLibrary.getConfiguration('firstName', {
  props: {
    label: 'New Label',
  },
});

Retrieving Configuration Groups

Similar to configurations, configuration groups are predefined groups of fields that will often be used together.
They are defined in the field-library.module.ts (refer to the next section for details).

You can retrieve a configuration group with the getConfigurationGroup method, which returns a FormlyFieldConfig[].

For example, the following code snippet will return an array of configurations containing title, firstName, lastName and phoneHome field configurations per default:

this.fields = this.fieldLibrary.getConfigurationGroup('personalInfo');

Just like the singular getConfiguration method, it is possible to override any FormlyFieldConfigs provided by getConfigurationGroup.
To do so, use the optional overrides property.
Because getConfigurationGroup returns multiple field configurations, you will have to specify which configurations to modify.

For example, the following code snippet will return the personalInfo configuration group but modify firstName to not be required anymore and update the lastName field's label:

this.fieldLibrary.getConfigurationGroup('personalInfo', {
  firstName: {
    props: {
      required: false,
    },
  },
  lastName: {
    props: {
      label: 'new and improved label',
    },
  },
});

Defining Your Own Configurations & Configuration Groups

Whether you are customizing the PWA in a project or contributing to the standard, you might need to expand the field library with further field configurations.
These provided configurations & configurations groups will be processed by the FieldLibrary and made accessible via the relevant methods.

All configurations are registered in the field-library.module.ts.

Defining a FieldLibraryConfiguration

To define a new reusable field configuration, use the field-library-configuration schematic.
It will generate a .configuration.ts file and register the configuration in the providers array of the module.
Populate the file with whatever logic you need and let the getConfiguration() method return a FormlyFieldConfig.
You can return a static value or inject services and create a dynamic, smart configuration.

Defining a FieldLibraryConfigurationGroup

To define a new reusable configuration group, provide a new value for the FIELD_LIBRARY_CONFIGURATION_GROUP injection token.
The value has to conform to the ConfigurationGroup type.

// ConfigurationGroup type
type ConfigurationGroup = { id: string; shortcutFor: string[] };

// field-library.module.ts
...
{
  provide: FIELD_LIBRARY_CONFIGURATION_GROUP,
  useValue: { id: 'exampleGroup', shortcutFor: ['firstName', 'lastName', 'companyName'] },
  multi: true,
},
...

Use the id property to define the id through which developers will access the configuration group.

The shortcutFor property defines which configurations the group will be mapped to.
You can introduce dynamic behavior by using factory providers to generate ConfigurationGroup objects.

Automatic Field Replacement Using the '#' Pseudo-Type

For an even cleaner development experience, it is possible to reuse formly field configurations without using the FieldLibrary, saving a lot of boiler-plate code.

To take advantage of this feature, you can use the pseudo-types prefixed by a #.
For example, if you want to use the firstName configuration in your form, add the following object to your FormlyFieldConfig[]:

{
  type: '#firstName',
}

Behind the scenes, this will automatically be replaced by the firstName configuration.
To take advantage of override logic, add the modifications to the object.
For example, defining a new label text works like this:

{
  type: '#firstName',
  props: {
    label: 'New Label',
  }
}

This is equivalent to the example given in Retrieving configurations but does not require you to inject the library.

Address Forms

Address forms are a special kind of reusable forms and as such are treated differently in the Intershop PWA.
Under the hood, they also use the functionality explained above, but the address configurations are declared in their own module and access to address forms is simplified via the formly-address-form component.

Using the formly-address-form Component

The following steps describe how to use the formly-address-form component on your form (also see the example below):

Container component:

1. Create a FormGroup. It will be populated with an address control.

Container template:

1. Add a <ish-formly-address-form> component to your template.
2. Pass your FormGroup via the parentForm input.
3. Optional: Define whether you want to display business customer addresses via the businessCustomer input.
4. Optional: Define whether you want to have the address form pre-filled via the prefilledAddress input.

Creating a New Country Specific Form

Use the address-form-configuration (or shortcut afc) schematic with your desired countryCode parameter.
This will create a new configuration under src/app/shared/formly-address-forms/configurations and register it in the formlyAddressFormsModule.
An empty example configuration looks like this:

...

@Injectable()
export class AddressFormEXConfiguration extends AddressFormConfiguration {
  countryCode = 'EX';

  constructor() {
    super();
  }

  getModel(model: Partial<Address> = {}): Partial<Address> {
    return {
      ...model,
    };
  }

  getFieldConfiguration(): FormlyFieldConfig[] {
    return [];
  }
}

• getFieldConfiguration and getModel will automatically be called by the formly-address-form component when a new country is selected. They are used to populate the address form. The businessCustomer attribute will be set automatically, based on what you passed to the formly-address-form. You can use it to adjust the configuration and model.

• Define the field configuration in getFieldConfiguration.

• Define the model for the country form in getModel. The method will be called with the previous model to make keeping field values between countries possible.

• Use the addressesFieldConfiguration helper method to quickly reuse common address field configurations (see standardFields).

Standard Reusable Form Configurations

The following is a list of reusable field configurations available in the PWA.

Further References

• Formly documentation
• General forms documentation