---
Added: v2.0.0
---
# Form Extensibility and Customisation

_Note: it is assumed you are familiar with Alfresco Process Services (powered by Activiti) form definition structure._

-   How components and widgets are rendered on a Form
-   Replacing default form widgets with custom components
-   Replacing custom stencils with custom components

## How components and widgets are rendered on a Form

All form field editors (aka widgets) on a Form are rendered by means of `FormFieldComponent`
that takes an instance of a `FormFieldModel`:

```html
<form-field [field]="field"></form-field>
```

This component depends on `FormRenderingService` service to map `FormFieldModel` to UI component
based on field type or metadata information.

### Component type resolvers

`FormRenderingService` maps field types to corresponding instances exposing `ComponentTypeResolver` interface:

```ts
export interface ComponentTypeResolver {
    (field: FormFieldModel): Type<{}>;
}
```

Typically a `ComponentTypeResolver` is a function that takes `FormFieldModel` and returns corresponding component type.
It can be either a predefined component type or a dynamically evaluated based on field properties and metadata.

#### Static component mapping

You can (re)map fields like in the following:

```ts
let customResolver: ComponentTypeResolver = () => CustomWidgetComponent;
formRenderingService.setComponentTypeResolver('text', customResolver, true);
```

or simply:

```ts
formRenderingService.setComponentTypeResolver('text', () => CustomWidgetComponent, true);
```

#### Dynamic component mapping

Alternatively your resolver may return different component types based on `FormFieldModel` state and condition:

```ts
let customResolver: ComponentTypeResolver = (field: FormFieldModel): Type<{}> => {
    if (field) {
        let params = field.params;
    }
    return UnknownWidgetComponent;
};
formRenderingService.setComponentTypeResolver('text', customResolver, true);
```

### Default component mappings

| Stencil Name | Field Type | Component Type |
| ------------ | ---------- | -------------- |
| Text | text | TextWidgetComponent |
| Number | integer | NumberWidgetComponent |
| Multi-line text | multi-line-text | MultilineTextWidgetComponentComponent |
| Checkbox | boolean | CheckboxWidgetComponent |
| Dropdown | dropdown | DropdownWidgetComponent |
| Date | date | DateWidgetComponent |
| Amount | amount | AmountWidgetComponent |
| Radio buttons | radio-buttons | RadioButtonsWidgetComponent |
| Hyperlink | hyperlink | HyperlinkWidgetComponent |
| Display value | readonly | DisplayValueWidgetComponent |
| Display text | readonly-text | DisplayTextWidgetComponentComponent |
| Typeahead | typeahead | TypeaheadWidgetComponent |
| People | people | PeopleWidgetComponent |
| Group of people | functional-group | FunctionalGroupWidgetComponent |
| Dynamic table | dynamic-table | DynamicTableWidgetComponent |
| N/A | container | ContainerWidgetComponent (layout component) |
| Header | group | ContainerWidgetComponent |
| Attach | upload | AttachWidgetComponent or UploadWidgetComponent (based on metadata) |
| N/A | N/A | UnknownWidgetComponent |

## Replacing default form widgets with custom components

This is a short walkthrough on replacing a standard `Text` widget with a custom component for all APS forms
rendered within `<adf-form>` component.

First let's create a simple APS form with `Text` widgets:

![default text widget](docassets/images/text-default-widget.png)

Every custom widget must inherit `WidgetComponent` class in order to function properly:

```ts
import { Component } from '@angular/core';
import { WidgetComponent } from '@alfresco/adf-core';

@Component({
    selector: 'custom-editor',
    template: `
        <div style="color: red">Look, I'm a custom editor!</div>
    `
})
export class CustomEditorComponent extends WidgetComponent {}
```

Now you will need to add it to the application module or any custom module that is imported into the application one:

```ts
import { NgModule } from '@angular/core';
import { CustomEditorComponent } from './custom-editor.component';

@NgModule({
    declarations: [ CustomEditorComponent ],
    exports: [ CustomEditorComponent ],
    entryComponents: [ CustomEditorComponent ]
})
export class CustomEditorsModule {}
```

Every custom widget should be added into all three module collections: `declarations`, `exports` and `entryComponents`.

If you decided to store custom widgets in a separate dedicated module (and optionally as separate redistributable library)
don't forget to import it into your main application one:

```ts
@NgModule({
    imports: [
        // ...
        CustomEditorsModule
        // ...
    ],
    providers: [],
    bootstrap: [ AppComponent ]
})
export class AppModule {}
```

Now you can import `FormRenderingService` in any of your Views and override default mapping similar to the following:

```ts
import { Component } from '@angular/core';
import { CustomEditorComponent } from './custom-editor.component';

@Component({...})
export class MyView {

    constructor(formRenderingService: FormRenderingService) {
        formRenderingService.setComponentTypeResolver('text', () => CustomEditorComponent, true);
    }

}
```

At runtime it should look similar to the following:

![custom text widget](docassets/images/text-custom-widget.png)

## Replacing custom stencils with custom components

This is a short walkthrough on rendering custom APS stencils by means of custom Angular components.

### Creating custom stencil

First let's create a basic stencil and call it `Custom Stencil 01`:

![custom stencil](docassets/images/activiti-stencil-01.png)

_Note the `internal identifier` value as it will become a `field type` value when corresponding form is rendered._

Next put some simple html layout for `Form runtime template` and `Form editor template` fields:

```html
<div style="color: blue">Custom activiti stencil</div>
```

Now you are ready to design a test form based on your custom stencil:

![custom stencil form](docassets/images/activiti-stencil-02.png)

Once wired with a new task it should look like the following within APS web application:

![custom stencil task](docassets/images/activiti-stencil-03.png)

### Creating custom widget

If you load previously created task into ADF `<adf-form>` component you will see something like the following:

![adf stencil](docassets/images/adf-stencil-01.png)

Let's create an Angular component to render missing content:

```ts
import { Component } from '@angular/core';
import { WidgetComponent } from '@alfresco/adf-core';

@Component({
    selector: 'custom-stencil-01',
    template: `<div style="color: green">ADF version of custom Activiti stencil</div>`
})
export class CustomStencil01 extends WidgetComponent {}
```

Put it inside custom module:

```ts
import { NgModule } from '@angular/core';
import { CustomStencil01 } from './custom-stencil-01.component';

@NgModule({
    declarations: [ CustomStencil01 ],
    exports: [ CustomStencil01 ],
    entryComponents: [ CustomStencil01 ]
})
export class CustomEditorsModule {}
```

And import into your Application Module

```ts
@NgModule({
    imports: [
        // ...
        CustomEditorsModule
        // ...
    ],
    providers: [],
    bootstrap: [ AppComponent ]
})
export class AppModule {}
```

Now you can import `FormRenderingService` in any of your Views and provide new mapping:

```ts
import { Component } from '@angular/core';
import { CustomStencil01 } from './custom-stencil-01.component';

@Component({...})
export class MyView {

    constructor(formRenderingService: FormRenderingService) {
        formRenderingService.setComponentTypeResolver('custom_stencil_01', () => CustomStencil01, true);
    }

}
```

At runtime you should now see your custom Angular component rendered in place of the stencils:

![adf stencil runtime](docassets/images/adf-stencil-02.png)

## See Also

-   [Form field model](form-field.model.md)
-   [Form rendering service](form-rendering.service.md)
-   [Form component](form.component.md)
-   [Widget component](widget.component.md)
