A required boolean, a checkbox and validation about react-jsonschema-form HOT 7 CLOSED

checkbox{
type: ‘boolean’,
default: null,
enum: [null, true],
}

from react-jsonschema-form.

I tested the following schema:

const schema = {
  "type": "object",
  "title": "Testform",
  "properties": {
    "title": {
      "type": "string",
      "title": "Title",
      "default": ""
    },
    "flags.pure": {
      "type": "boolean",
      "title": "Only typed as boolean",
    },
    "flags.withDefault": {
      "type": "boolean",
      "title": "Typed as boolean and with default: false",
      "default": false
    },
    "flags.withEnum": {
      "type": "boolean",
      "title": "Typed as boolean and with enum: [false, true]",
      "enum": [true, false]
    },
    "flags.withEnumAndDefault": {
      "type": "boolean",
      "title": "Typed as boolean and with enum: [false, true] and default: false",
      "default": false,
      "enum": [true, false]
    }
  },
  "description": "Testform's description.",
  "required": [
    "flags.pure",
    "flags.withDefault",
  ]
};

The results are:

• "empty" default values are ignored (this does apply for boolean false, string "" and probalby [untested] number 0).
• The work-around using { "enum": [ true, false ] } and not setting the field to required does work.

In my opinion, a required boolean checkbox should not fail the validation if it is set to false. If I wan't the form to fail validation in this case, I should limit the allowed value for this field using the enum operator.

I understand the argument that "no user action" does not equals "setting a value to false". If you want to follow this argument I think the following three cases should pass validation (but don't do at the moment):

• The checkbox has no default, the user first checks it and then decides to un-check it before submitting the form.
• The checkbox has the default value of falseand the user doesn't change the value.
• The checkbox has the default value of trueand the user decides to un-check the box (e.g. opt-out for a newsletter).

from react-jsonschema-form.

Didn't test but does setting an explicit default value solve the issue?

{
  type: "boolean",
  default: false
}

Actually it makes sense to me for validation to fail if no default value as been set and no action has been performed by the user just yet.

from react-jsonschema-form.

I had a similar feeling and I was wondering if it wasn't to address cases when you actually want the checkbox to be checked (I have read theTOS for instance)

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@n1k0 As I understand this, but please correct me if I'm wrong, your change now reads default values from the schema if they exist, is that correct? That means that a boolean field will be rendered as a checkbox by default, and unless the schema sets a default value of false, the checkbox must be checked. Is that correct?

Checkboxes are tricky. I can see the logic in this approach. I can also see @HelloLudger's point that it instinctively feels unintuitive. I'm also not sure what a more elegant solution looks like. The humble <input type="checkbox" does not provide a means to distinguish between unset and false.

Maybe this should be explained a little in the docs? Something like this?

Boolean gotchas

By default, a boolean field will be rendered using the checkbox widget. If the field is submitted unchecked, it's value will be undefined. If the schema includes this field in required, then the submission will fail because the field is neither true nor false. This can be useful for compulsory true fields like "Agree to terms" checkboxes and so on. If you want the unchecked checkbox value to be false, you can specify default: false in the schema for that field.

Having just written that, I wonder if this is the most intuitive approach. I suppose it would be a breaking change to modify this behaviour, but somehow I have the sense that out of the box, an unchecked checkbox should set the value false if empty, and true if checked. Then if somebody wants to require a value of true, they can (presumably, maybe?) specify that in the schema.

I also suppose, that currently, there is no way to have a boolean field which can be either true, false or empty. Either the select or the radio widgets will only render true or false as options, and the select will automatically default the first option, and the radio doesn't provide a way to "unselect" an option in most browsers.

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PS> Of course much of this is now solvable with custom field types, as per #77...

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checkbox{ type: ‘boolean’, default: null, enum: [null, true], }

You are a genius!!

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