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Developing a Custom Form Field for Liferay 7.2

React-based custom form fields can be developed for Liferay 7.3 and Liferay 7.4. See Writing Custom Form Field Types to learn how. Liferay 7.2 used a different frontend technology, based on MetalJS and Soy closure templates. In this tutorial you can learn to adapt the React-based Acme C2P9 Slider field to run on a Liferay 7.2 installation.

Adjusting the Acme C2P9 Slider to Run on Liferay 7.2

Liferay 7.2 used a different frontend framework for custom form fields. To adjust the Acme C2P9 Slider field in order to run it on Liferay 7.2,

Download and unzip the Custom Forms Field Type project.

curl https://resources.learn.liferay.com/examples/liferay-c2p9.zip -O

unzip liferay-c2p9.zip

Open the liferay-c2p9.zip/gradle.properties file and change the line

liferay.workspace.product=portal-7.4-ga8

liferay.workspace.product=portal-7.2-ga2

Open the liferay-c2p9.zip/settings.gradle file and change the line

classpath group: "com.liferay", name: "com.liferay.gradle.plugins.workspace", version: "latest.release"

classpath group: "com.liferay", name: "com.liferay.gradle.plugins.workspace", version: "3.4.17"

Open the liferay-c2p9.zip/c2p9-impl/build.gradle file and add the lines

 compileOnly group: "org.osgi", name: "osgi.cmpn"
 jsCompile group: "com.liferay", name: "com.liferay.dynamic.data.mapping.form.field.type"

Open the liferay-c2p9.zip/c2p9-impl/package.json file. Begin by replacing the devDependencies line

 "@liferay/portal-7.4": "*"

with these two lines:

 "@liferay/portal-7.2": "*",
 "metal-tools-soy": "4.3.2"

Then replace the existing scripts content (two lines) with these three lines:

"build": "npm run build-soy && npm run build-js && liferay-npm-bundler",
"build-js": "babel --source-maps -d build/resources/main/META-INF/resources src/main/resources/META-INF/resources",
"build-soy": "metalsoy --externalMsgFormat \"Liferay.Language.get('\\$2')\" --soyDeps \"./node_modules/clay-*/src/**/*.soy\" \"./node_modules/com.liferay.dynamic.data.mapping.form.field.type/META-INF/resources/+(FieldBase|components)/**/*.soy\""

Open the liferay-c2p9.zip/c2p9-impl/bnd.bnd file and add these lines:
```
Provide-Capability:\
	soy;\
		type:String="LiferayFormField"
```
Replace the contents of liferay-c2p9.zip/c2p9-impl/.babelrc.js with
```
module.exports = {
    presets: ['@babel/preset-env'],
};
```
Checkpoint: The project is reconfigured to expect the 7.2 frontend framework, so you must replace the frontend of the form field project.

Remove the existing Slider.es.js file and create these three files to replace it:

Slider.es.js: the new slider component using the MetalJS + Soy frontend.

import 'dynamic-data-mapping-form-field-type/FieldBase/FieldBase.es';
import './SliderRegister.soy.js';
import templates from './Slider.soy.js';
import Component from 'metal-component';
import Soy from 'metal-soy';
import {Config} from 'metal-state';

class Slider extends Component {

    dispatchEvent(event, name, value) {
        this.emit(name, {
            fieldInstance: this,
            originalEvent: event,
            value
        });
    }

    _handleFieldChanged(event) {
        const {value} = event.target;

        this.setState(
            {
                value
            },
            () => this.dispatchEvent(event, 'fieldEdited', value)
        );
    }
}

Slider.STATE = {

    label: Config.string(),

    name: Config.string().required(),

    predefinedValue: Config.oneOfType([Config.number(), Config.string()]),

    required: Config.bool().value(false),

    showLabel: Config.bool().value(true),

    spritemap: Config.string(),

    value: Config.string().value('')
}

Soy.register(Slider, templates);

export default Slider;

Slider.soy: the Soy template for the field.

{namespace Slider}

{template .render}
    {@param label: string}
    {@param name: string}
    {@param showLabel: bool}
    {@param tip: string}
    {@param value: ?}
    {@param? _handleFieldChanged: any}
    {@param? predefinedValue: any}
    {@param? required: bool}
    {@param? spritemap: string}

    {call FieldBase.render}
        {param contentRenderer kind="html"}
            {call .content}
                {param _handleFieldChanged: $_handleFieldChanged /}
                {param name: $name /}
                {param predefinedValue: $predefinedValue /}
                {param value: $value /}
            {/call}
        {/param}
        {param label: $label /}
        {param name: $name /}
        {param required: $required /}
        {param showLabel: $showLabel /}
        {param spritemap: $spritemap /}
        {param tip: $tip /}
    {/call}
{/template}

{template .content}
    {@param name: string}
    {@param value: ?}
    {@param? _handleFieldChanged: any}
    {@param? predefinedValue: any}
    {let $attributes kind="attributes"}
        class="ddm-field-slider form-control slider"

        data-oninput="{$_handleFieldChanged}"

        id="myRange"

        max="100"

        min="1"

        name="{$name}"

        type="range"

        {if $value}
            value="{$value}"
        {else}
            value="{$predefinedValue}"
        {/if}
    {/let}

    <input {$attributes}>
{/template}

SliderRegister.soy: the registration code for the Slider’s Soy template.

{namespace SliderRegister}

{deltemplate PageRenderer.RegisterFieldType variant="'slider'"}
    {call Slider.render data="all" /}
{/deltemplate}

A minor adjustment to the DDMFormFieldType is needed: the identifier for the field (the name) cannot have a hyphen (-) because it is referenced as a String literal in the Soy template. Open the C2P9DDMFormFieldType class and remove the hyphen from
- the component property ddm.form.field.type.name
- the String returned by getName
The value in both locations is now c2p9slider.
Once the project’s frontend is replaced, deploy it to a running Liferay 7.2.
- To start a Liferay 7.2 Docker container run
```
docker run -it -m 8g -p 8080:8080 liferay/portal:7.2.1-ga2
```
- To deploy the reconfigured form field project, go to the liferay-c2p9.zip folder and run
```
./gradlew deploy -Ddeploy.docker.container.id=$(docker ps -lq)
```
Confirm the deployment in the Liferay Docker container console.
```
STARTED com.acme.c2p9.impl_1.0.0 [1009]
```