uiSchema

JSON Schema is limited for describing how a given data type should be rendered as a form input component. That's why this library introduces the concept of uiSchema.

A UI schema is basically an object literal providing information on how the form should be rendered, while the JSON schema tells what.

The uiSchema object follows the tree structure of the form field hierarchy, and defines how each property should be rendered.

Note that every property within uiSchema can be rendered in one of two ways: {"ui:options": {[property]: [value]}}, or {"ui:[property]": value}.

In other words, the following uiSchemas are equivalent:

{
  "ui:title": "Title",
  "ui:description": "Description"
}
{
  "ui:options": {
    "title": "Title",
    "description": "Description"
  }
}

classNames

The uiSchema object accepts a classNames property for each field of the schema:

const uiSchema = {
  title: {
    classNames: "task-title foo-bar"
  }
};

Will result in:

<div class="field field-string task-title foo-bar" >
  <label>
    <span>Title*</span>
    <input value="My task" required="" type="text">
  </label>
</div>

autofocus

If you want to automatically focus on a text input or textarea input, set the ui:autofocus uiSchema directive to true.

const schema = {type: "string"};
const uiSchema = {
  "ui:widget": "textarea",
  "ui:autofocus": true
}

description

Sometimes it's convenient to change the description of a field. This is the purpose of the ui:description uiSchema directive:

const schema = {type: "string"};
const uiSchema = {
  "ui:widget": "password",
  "ui:description": "The best password"
};

disabled

The ui:disabled uiSchema directive will disable all child widgets from a given field.

Note: If you're wondering about the difference between a disabled field and a readonly one: Marking a field as read-only will render it greyed out, but its text value will be selectable. Disabling it will prevent its value to be selected at all.

enumDisabled

To disable an option, use the enumDisabled property in uiSchema.

const schema = {
  type: "string",
  enum: ["one", "two", "three"],
};

const uiSchema={
  "ui:enumDisabled": ['two'],
}

help

Sometimes it's convenient to add text next to a field to guide the end user filling it. This is the purpose of the ui:help uiSchema directive:

const schema = {type: "string"};
const uiSchema = {
  "ui:widget": "password",
  "ui:help": "Hint: Make it strong!"
};

Help texts work for any kind of field at any level, and will always be rendered immediately below the field component widget(s) (after contextualized errors, if any).

inputType

To change the input type (for example, tel or email) you can specify the inputType in the ui:options uiSchema directive.

const schema = {type: "string"};
const uiSchema = {
  "ui:options": {
    inputType: 'tel'
  }
};

label

Field labels are rendered by default. Labels may be omitted by setting the label option to false in the ui:options uiSchema directive.

const schema = {type: "string"};
const uiSchema = {
  "ui:options": {
    label: false
  }
};

render((
  <Form schema={schema} uiSchema={uiSchema} />
), document.getElementById("app"));

order

This property allows you to reorder the properties that are shown for a particular object. See Objects for more information.

placeholder

You can add placeholder text to an input by using the ui:placeholder uiSchema directive:

const schema = {type: "string", format: "uri"};
const uiSchema = {
  "ui:placeholder": "http://"
};

render((
  <Form schema={schema} uiSchema={uiSchema} />
), document.getElementById("app"));

Fields using enum can also use ui:placeholder. The value will be used as the text for the empty option in the select widget.

const schema = {type: "string", enum: ["First", "Second"]};
const uiSchema = {
  "ui:placeholder": "Choose an option"
};

render((
  <Form schema={schema} uiSchema={uiSchema} />
), document.getElementById("app"));

readonly

The ui:readonly uiSchema directive will mark all child widgets from a given field as read-only. This is equivalent to setting the readOnly property in the schema.

Note: If you're wondering about the difference between a disabled field and a readonly one: Marking a field as read-only will render it greyed out, but its text value will be selectable. Disabling it will prevent its value to be selected at all.

rootFieldId

By default, this library will generate ids unique to the form for all rendered widgets. If you plan on using multiple instances of the Form component in a same page, it's wise to declare a root prefix for these, using the ui:rootFieldId uiSchema directive:

const uiSchema = {
  "ui:rootFieldId": "myform"
};

This will make all widgets have an id prefixed with myform.

rows

You can set the initial height of a textarea widget by specifying rows option.

const schema = {type: "string"};
const uiSchema = {
  "ui:widget": "textarea",
  "ui:options": {
    rows: 15
  }
};

render((
  <Form schema={schema} uiSchema={uiSchema} />
), document.getElementById("app"));

title

Sometimes it's convenient to change a field's title. This is the purpose of the ui:title uiSchema directive:

const schema = {type: "string"};
const uiSchema = {
  "ui:widget": "password",
  "ui:title": "Your password"
};

Theme Options

Semantic UI