Support for indeterminate checkboxes

[tgoldenberg]

Description

It would be great to be able to set indeterminate={true} on the <Checkbox/> components. Any suggestions for this, or is there a plan to include this?

Thank you!

Images & references

-->

[oliviertassinari]

@tgoldenberg I'm not sure to understand. What's the use case?

[nathanmarks]

@tgoldenberg

You can target it with css using the :indeterminate selector: https://developer.mozilla.org/en-US/docs/Web/CSS/:indeterminate

[nathanmarks]

And you should be able to access the DOM element with refs (edit - via our component) to set the property.

[nathanmarks]

@tgoldenberg facebook/react#1798

[tgoldenberg]

yeah, I tried using refs via this.checkbox.refs.enhancedToggle.refs... but haven't gotten it to work yet. I'll try to post an example if I get it working.

[nathanmarks]

@tgoldenberg What happens? does the DOM property reset after you change it?

[tgoldenberg]

@nathanmarks Nothing happens. Nothing.

[nathanmarks]

@tgoldenberg Did you add any :indeterminate styling? It's a visual only property. It looks like it's being set to true from your console.log output there.

[nathanmarks]

@tgoldenberg Just having a play with it now. I see the difficulty you're having here even with the property set. All I have right now with the current setup is something slightly hacky:

input[type="checkbox"]:indeterminate + div > div:after {
  content: 'indeterminate_check_box';
  font-family: 'Material Icons';
  font-size: 24px;
}

[nathanmarks]

I'll look into supporting this better in the next branch.

[Alxandr]

Just my 2 cents. One way to support this (that I would prefer) is to allow checked to be either true, false or 'indeterminate' (or explicitly null - not undefined). Instead of adding a new attribute. A check box is a system with 3 states, the input should reflect this IMHO.

[oliviertassinari]

@Alxandr I like the idea of keeping everything under one property as put a hard constraint. The state can't be 'indeterminate' and true or false at the same time => simplicity.

[Alxandr]

Yeah. I seem to recall (from WPF in .NET or something similar) that checkboxes checked state was typed as a bool? (that is, either true, false or null). That made a lot of sense to me. Problem in javascript thought is that since it's untyped, using null has a tendency to be equated to undefined and false. But still, I think this makes sense:

const Test = () => (
  <div>
    <Checkbox /> // unchecked
    <Checkbox checked />  // checked
    <Checkbox checked={null} /> // indeterminate
  </div>
);

I think this is sufficiently explicit, though on the other hand it might be safer to do 'indeterminate'. But I still think it's better than adding a new prop nontheless.

[gulderov]

There is some trouble with null. If you initially pass null to component. It will be "uncontrolled". Once you play with component it will bring to "controlled".

SwitchBase is changing a controlled input of type checkbox to be uncontrolled. Input elements should not switch from controlled to uncontrolled (or vice versa). Decide between using a controlled or uncontrolled input element for the lifetime of the component. More info: https://fb.me/react-controlled-components.

React itself does not support indeterminate checkboxes facebook/react#1798.

https://www.w3.org/TR/2014/WD-html51-20140617/forms.html#checkbox-state-(type=checkbox) says:

The control is never a true tri-state control, even if the element's indeterminate IDL attribute is set to true. The indeterminate IDL attribute only gives the appearance of a third state.

It can be better to set separate prop for it.

[oliviertassinari]

It can be better to set separate prop for it.

@gulderov Yes, I agree. After benchmarking what other libraries are doing, I believe that blueprintjs is handling the problem very well. I would be awesome if we could do the same.

indeterminate boolean
Whether this checkbox is indeterminate, or "partially checked." The checkbox will appear with a small dash instead of a tick to indicate that the value is not exactly true or false.

[Alxandr]

@gulderov There is no reason material-ui can't create a better abstraction on top of the one provided by React itself though. And sure, null might be problematic (didn't think about controlled vs uncontrolled), but a tri-state could be implemented as something like this (without any stying etc, ofcause):

const Checkbox = ({ checked }) => {
  const checkedState = checked === null
    ? null
    : checked === 'indeterminate' : true ? false;
  const indeterminate = checked === 'indeterminate';
  return <checkbox checked={checkedState} indeterminate={indeterminate} />
}

[oliviertassinari]

@Alxandr Don't we lose an extra information? Isn't the point to notify that the value is mostly true of false but not completely? Let's say it's used in a regular Form, what's the value sent to the server?

[Alxandr]

Lose information? We lose no information.

A checkbox can be in one of 4 states technically:

• checked
• unchecked
• checked - indeterminate
• unchecked - indeterminate

If you change it to use only one prop, the only one you can't describe is unckeced - indeterminate, so then the question is does that make sense? I don't think it makes sense, hence I don't think we lose any information.

[Parthchokshi]

An indeterminate checkbox should have different styling I feel. I like how primeng does it.
https://www.primefaces.org/primeng/#/tristatecheckbox

[oliviertassinari]

@Parthchokshi The styling is different:

[Parthchokshi]

I meant, we don't have a tristate checkbox, it just toggles the color when I click on that. We can have it change icon when user click on it. The initial indeterminate state should be blank. And then yes/no should be tick/cross icons.

This should be really useful in RSVP UI's, where user can say:

• coming
• not coming
• haven't said anything yet.

May be a new component all by itself or extend Checkbox.

[veronicaerick]

Is there an update on how to create an unchecked indeterminate state that's blank rather than with a grey/secondary color in the background of the checkbox? I've tried pulling in different checkbox icons from MUIs selection (i.e. IndeterminateCheckBoxOutlined.js ) and added styles with the classes object to achieve what I want... but haven't had any luck going from unchecked indeterminate as an empty checkbox, to checked indeterminate using the default IndeterminateCheckBox icon/style

unchecked indeterminate

checked indeterminate

[oliviertassinari]

@veronicaerick Please submit questions like this on StackOverflow next time. People answers on GitHub don't compound as much. I would try something like this:

import React from 'react';
import Checkbox from '@material-ui/core/Checkbox';
import CheckBoxOutlineBlank from '@material-ui/icons/CheckBoxOutlineBlank';

export default function Checkboxes() {
  const [state, setState] = React.useState({
    checkedF: true,
  });

  const handleChange = (name: string) => (event: React.ChangeEvent<HTMLInputElement>) => {
    setState({ ...state, [name]: event.target.checked });
  };

  return (
    <Checkbox
      checked={state.checkedF}
      indeterminateIcon={state.checkedF ? undefined : <CheckBoxOutlineBlank />}
      onChange={handleChange('checkedF')}
      value="checkedF"
      indeterminate
      inputProps={{
        'aria-label': 'indeterminate checkbox',
      }}
    />
  );
}

https://codesandbox.io/s/material-demo-t8w8r

[veronicaerick]

will do, thank you so much for the response this works perfectly! 👍