silverstripe-framework/docs/en/02_Developer_Guides/15_Customising_the_Admin_Interface/How_Tos/Customise_React_Forms.md

title	summary
Customising React forms	Use Injector to add customisations to React-rendered forms

Customising React Forms

Forms that are rendered with React use the ReduxForm library and are based on schema definitions that come from the server. To customise these forms, you can apply middleware that updates the schema or applies validation.

Toggling a form field

Let's have a field hide or show based on the state of another field. We want the field "State" to show if Country === 'US'.

First, we need to add a customisation to all form fields that allows them to be toggleable.

_my-module/js/src/HideableComponent.js

import React from 'react';

const HideableComponent = ({Component, ...props}) => (
  props.shouldHide ? null : <Component {...props} />
);

HideableComponent.propTypes = {
  shouldHide: PropTypes.boolean
};

HideableComponent.defaultProps = {
  shouldHide: false
};

export default (Component) => (props) => (
  props.shouldHide ? null : <Component {...props} />
);

Now, let's apply this through Injector.

my-module/js/main.js

Injector.transform(
  'toggle-field',
  (updater) => {
    updater.component('ReduxFormField', HideableComponentCreator);
  }
);

Lastly, we need to apply a schema transformation using updater.form.alterSchema().

Injector.transform(
  'my-toggle',
  (updater) => {
    updater.form.alterSchema(
      'AssetAdmin.*',
      (form) =>
        form
          .updateField('State', {
            shouldHide: form.getValue('Country') !== 'US'
          })
          .getState()
    )
  }
);

Conditionally adding a CSS class to a form field

In this example, we'll add the class "danger" to the Price field when TicketsRemaining is less than 10.

Injector.transform(
  'my-css',
  (updater) => {
    updater.form.alterSchema(
      'AssetAdmin.*',
      (form) =>
        form
          .setFieldClass('Price', 'danger', (form.getValue('TicketsRemaining') < 10))
          .getState()
    );
  }
);

Using a custom component

In this example, we'll replace a plain text field for PhoneNumber with one that is broken up into three separate text fields.

First, we need to create the PrettyPhoneNumberField component.

my-module/js/src/PrettyPhoneNumberField.js

import React from 'react';

export default (props) => {
  const [area, exchange, ext] = props.value.split('-');
  function handleChange (i, e) {
    const parts = props.value.split('-');
    parts[i] = e.target.value;
    const formatted = parts.join('-');
    props.onChange(formatted, e);
  };
  return (
    <div>
      (<input type="text" value={area} onChange={handleChange.bind(null, 0)}/>)
      <input type="text" value={exchange} onChange={handleChange.bind(null, 1)}/> -
      <input type="text" value={ext} onChange={handleChange.bind(null, 2)}/>
    </div>
  );
};

Now, we'll need to override the PhoneNumber field with custom component.

Injector.transform(
  'my-custom-component',
  (updater) => {
    updater.form.alterSchema(
      'AssetAdmin.*',
      (form) =>
        form
          .setFieldComponent('PhoneNumber', 'PrettyPhoneNumberField')
          .getState()
    );
  }
);

Custom validation

In this example, we'll add a computed validation rule. If Country is set to "US", we'll validate the postal code against a length of 5. If not, we'll use a length of 4.

Injector.transform(
  'my-validation',
  (updater) => {
    updater.form.addValidation(
      'AssetAdmin.*',
      (values, errors) => {
        const requiredLength = values.Country === 'US' ? 5 : 4;
        if (!values.Country || !values.PostalCode) {
          return;
        }
        return {
          ...errors,
          PostalCode: values.PostalCode.length !== requiredLength ? 'Invalid postal code' : null,
        };
      }
    )
  }
);

Adding a "confirm" state to a form action

In this example, we'll have a form action expose two new buttons for "confirm" and "cancel" when clicked. This type of behaviour could be useful for a delete action, for instance, as an alternative to throwing window.confirm().

First, we need to create the ConfirmingFormAction component.

my-module/js/src/ConfirmingFormAction.js

import React from 'react';

export default (FormAction) => {
 class ConfirmingFormAction extends React.Component 
 {
    constructor(props) {
      super(props);
      this.state = { confirming: false };
      this.confirm = this.confirm.bind(this);
      this.cancel = this.cancel.bind(this);
      this.preClick = this.preClick.bind(this);
    }
    
    confirm(e) {
      this.props.handleClick(e, this.props.name || this.props.id);
      this.setState({ confirming: false });
    }
    
    cancel() {
      this.setState({ confirming: false });
    }
    
    preClick(event) {
      event.preventDefault();
      this.setState( {confirming: true });
    }

    render() {
      const { confirmText, cancelText } = this.props;
      const buttonProps = {
        ...this.props,
        extraClass: 'ss-ui-action-constructive',
        attributes: {
          ...this.props.attributes,
          type: 'button'
        },
      };
      delete buttonProps.name;
      delete buttonProps.type;

      const hideStyle = {
        display: this.state.confirming ? null : 'none'
      };

      return (
        <div>
          <FormAction { ...buttonProps } handleClick={this.preClick} />
          <button style={hideStyle} key="confirm" type="submit" name={this.props.name} onClick={this.confirm}>
            {confirmText}
          </button>
          <button style={hideStyle} key="cancel" type="button" onClick={this.cancel}>{cancelText}</button>
        </div>
      );
    }
  }

  return ConfirmingFormAction;
}

Now, let's apply this new component to a very specific form action.

Injector.transform(
  'my-confirm',
  (updater) => {
    updater.form.alterSchema(
      'AssetAdmin.*',
      (form) =>
          form
            .updateField('action_delete', {
              confirmText: 'Are you sure you want to delete?',
              cancelText: 'No!! Cancel!!!!'
            })
            .getState()
    )
  }
);