6. Customizable columns

Let’s add a bit more control over how the columns are rendered. This is quite a “low hanging fruit” thanks to the volto-object-widget add-on. This add-on has another dependency, the volto-blocks-form, so let’s add them both:

yarn workspace @plone-collective/datatable-tutorial add eea/volto-object-widget
yarn workspace @plone-collective/datatable-tutorial add eea/volto-blocks-form


You can use a specific version or branch when adding the dependency, research first the latest released version for these add-ons

Add the volto-object-widget add-on in the project’s package.json:

    "addons": [

The order in which we load the add-ons can sometimes be relevant. Ideally the configuration options are used only at “runtime”, on demand, but there are cases when an add-on can depend on a specific configuration at “configure time”.

It’s not our case, though. It’s still a good idea to list generic add-ons first.


we’ve had to add @eeacms/volto-blocks-form to the add-ons list to help Volto’s webpack resolver, as we’re distributing this add-on in “source code form”.

What would we like to change about the columns? Let’s go for: title, text align and another field that would allow us to tweak how the values are rendered.

We’ll continue without i18n integration for now, to keep things simpler. Within src/DataTable/schema.js add:

const ColumnSchema = (props) => ({
  title: 'Column',
  fieldsets: [
      id: 'default',
      title: 'Default',
      fields: ['column', 'title', 'textTemplate', 'textAlign'],
  properties: {
    title: {
      title: 'Header',
    textTemplate: {
      title: 'Text template',
      description: 'Add suffix/prefix to text. Use {} for value placeholder',
    textAlign: {
      title: 'Align',
      // widget: 'text_align',
      choices: [
        ['left', 'left'],
        ['center', 'center'],
        ['right', 'right'],
    column: {
      title: 'Data column',
      choices: [],
  required: ['column'],

Now, let’s make use of this schema. We’ll add a new field to the TableSchema to src/DataTable/schema.js:

properties: {
    columns: {
      title: 'Columns',
      description: 'Leave empty to show all columns',
      schema: ColumnSchema({ intl }),
      widget: 'object_list_inline',

Don’t forget to add the columns field name to the default fieldset. Within src/DataTable/schema.js TableSchema default fieldset add:

export const TableSchema = ({ intl }) => ({
  title: 'Data table',

  fieldsets: [
      id: 'default',
      title: intl.formatMessage(messages.defaultFieldset),
      fields: ['file_path', 'columns'], // columns added to fields
    // ...

Now we need to plug the available columns as choices to the schema. In Plone’s world we would write an adapter that binds the widget to the context or something like that. Let’s keep things really simple though and hard code the available choices to the schema. We could do this in the schema function, but it’s better to keep the schema readable and without logic, so we’ll mutate the schema in the component, before we pass it to the <InlineForm> component. Within src/DataTable/DataTableEdit.js replace DataTableEdit code block with:

const DataTableEdit = (props) => {
  const { selected, onChangeBlock, block, data, file_data } = props;
  const schema = TableSchema(props);
  const choices = (file_data?.meta?.fields || []).sort().map((n) => [n, n]);
  schema.properties.columns.schema.properties.column.choices = choices;

  return (
    // <> represents a React Fragment see https://reactjs.org/docs/fragments.html#short-syntax for more details
      <SidebarPortal selected={selected}>
          onChangeField={(id, value) => {
            onChangeBlock(block, {
              [id]: value,
      <DataTableView {...props} />

We’ll need to also inject the file data to the edit form, we didn’t need to before, but now it needs to know what are the available columns. Now that we’re wrapping the edit component in two HOCs, we’ll use Redux’s compose to play nice. This means that we need to first import the compose method from redux within our src/DataTable/DataTableEdit.js file:

import { compose } from 'redux';
import {
} from '@plone-collective/datatable-tutorial/hocs';

Then within src/DataTable/DataTableEdit.js add bellow the DataTableEdit code block:

const getFilePath = ({ data: { file_path } }) => file_path;

export default compose(
    icon: tableSVG,
    title: 'Data table',

Let’s go back to the view component and use the column definitions from the block data. Within src/DataTable/DataTableView.js replace the existing ``DataTableView``code block with:

const DataTableView = ({ file_data, data }) => {
  const columns =
    data.columns?.length > 0
      ? data.columns
      : file_data?.meta?.fields?.map((n) => ({
          column: n,

  return file_data ? (
    <Table {...format(data)}>
          {columns.map((col, i) => (
            <Table.HeaderCell key={i} textAlign={col.textAlign}>
              {col.title || col.column}
        {file_data.data.map((o, i) => (
          <Table.Row key={i}>
            {columns.map((col, y) => (
              <Table.Cell textAlign={col.textAlign}>
                  ? col.textTemplate.replace('{}', o[col.column])
                  : o[col.column]}
  ) : (
    <div>No data</div>

These minimal changes enable our code to have custom column titles, custom text align and to affect the way the values are rendered in the cells.

Of course, now the sky is the limit. We could enhance this with number formatting provided by a library to humanize and automatically format those values, or d3’s format. There’s plenty of choices.


6.1. Write a new Volto widget

Let’s enhance the edit form by creating an align widget for the text align field. Let’s create src/widgets/TextAlign.jsx.

import React from 'react';
import { Button } from 'semantic-ui-react';
import { FormFieldWrapper, Icon } from '@plone/volto/components';

import alignLeftSVG from '@plone/volto/icons/align-left.svg';
import alignRightSVG from '@plone/volto/icons/align-right.svg';
import alignJustifySVG from '@plone/volto/icons/align-justify.svg';
import alignCenterSVG from '@plone/volto/icons/align-center.svg';

const VALUE_MAP = [
  ['left', alignLeftSVG],
  ['right', alignRightSVG],
  ['center', alignCenterSVG],
  ['justify', alignJustifySVG],

export default (props) => {
  const { value, onChange, id } = props;
  return (
    <FormFieldWrapper {...props}>
      <div className="align-tools">
        {VALUE_MAP.map(([name, icon]) => (
              active={value === name}
              onClick={() => {
                onChange(id, name);
              <Icon name={icon} size="24px" />

We also need to create``src/widget/index.js`` file in order to export our widget:

export TextAlign from './TextAlign';

Now we’ll register it in the addon src/index.js default configuration method:

import { TextAlign } from './widgets';

// ... change in the default configuration function
if (!config.widgets.widget.text_align)
    config.widgets.widget.text_align = TextAlign;

An widget is a component with three main properties: id, value and onChange. The widget needs to call back the onChange with id and new value. To conform to the UI requirements Volto provides the FormFieldWrapper component which works on a very nice and easy principle: drop whatever control inside it, as a child and it will render that control neatly wrapped with the label, description, error messages, etc. This concept is somewhat similar to Zope’s ZPT macro and slot system.

Now go back to the schema and let’s use the new text align widget. Within src/DataTable/schema.js uncomment the widget use from TableSchema textAlign property:

// change in TableSchema properties
textAlign: {
  title: 'Align',
  widget: 'text_align', // we can now use the text_align widget
  choices: [
    ['left', 'left'],
    ['center', 'center'],
    ['right', 'right'],


volto-object-widget provides drag/drop sorting of the columns so it’s possible to reorder the columns.


We could say it’s done for now… but let’s go some steps further and explore how to further enhance this add-on’s re-usability and extensibility.