Valued Components (Data Binding)

Valued components are interactive components that can read from and write to form data. They are the backbone of interactive forms, enabling two-way data synchronization between the UI and the data model. This guide explains how to create components with data binding capabilities.

What Are Valued Components?

Valued components are components that:

✅ Read data from the form store
✅ Write data back to the form store
✅ Support two-way data binding
✅ Trigger validation automatically
✅ Track dirty/touched state
✅ Integrate with FormEngine’s reactive system

Common Examples:

Text inputs
Checkboxes and radio buttons
Dropdown selects
Date pickers
Sliders and range inputs
Custom interactive widgets

Understanding Data Binding

Data binding is the automatic synchronization between a component’s visual state and the form data store. When a user interacts with a valued component:

User Action → User types in input, checks a box, etc.
Component Update → Component calls onChange with new value
Store Update → FormEngine updates the data store
Validation → Validation runs (if enabled)
UI Sync → All components bound to that data key update automatically

User types "Hello" → Input onChange("Hello") → Store updates → Validation runs → Other components refresh

Creating Your First Valued Component

Use valued to set the component property that will be displayed in the form data. Only one property of a component can be valued.

Example: Custom Rating Component

Let’s create a star rating component that stores a numeric value (1-5) in the form data.

interface StarProps {
  color?: string
}

const Star = ({color}: StarProps) => (
  <svg
    width="24"
    height="24"
    viewBox="0 0 24 24"
    fill={color}
    stroke={color}
    strokeWidth="1"
  >
    <path d="M12 2l3.09 6.26L22 9.27l-5 4.87 1.18 6.88L12 17.77l-6.18 3.25L7 14.14 2 9.27l6.91-1.01L12 2z"/>
  </svg>
)

interface StarButtonProps {
  starNumber: number
  color?: string
  onClick?: () => void
  onMouseEnter?: () => void
}

const StarButton = ({
                      starNumber,
                      color,
                      onClick,
                      onMouseEnter
                    }: StarButtonProps) => {
  return <button
    type="button"
    className="star-rating__star"
    onClick={onClick}
    onMouseEnter={onMouseEnter}
    aria-label={`Rate ${starNumber} star${starNumber > 1 ? 's' : ''}`}
  >
    <Star color={color}/>
  </button>
}

// Step 1: Create the React component
interface StarRatingProps {
  /** Current rating value (1-5) */
  value: number;

  /** Called when rating changes */
  onChange?: (value: number) => void;

  /** Number of stars to show */
  maxStars?: number;

  /** Star color when active */
  activeColor?: string;

  /** Star color when inactive */
  inactiveColor?: string;
}

export const StarRating = ({
                             value,
                             onChange,
                             maxStars,
                             activeColor,
                             inactiveColor
                           }: StarRatingProps) => {
  const [hoveredStar, setHoveredStar] = useState<number | null>(null)

  const handleStarClick = (starValue: number) => {
    onChange?.(starValue)
  }

  const handleMouseEnter = (starValue: number) => {
    setHoveredStar(starValue)
  }

  const handleMouseLeave = () => {
    setHoveredStar(null)
  }

  const getStarColor = (starIndex: number) => {
    const effectiveRating = hoveredStar || value
    return starIndex <= effectiveRating ? activeColor : inactiveColor
  }

  return (
    <div
      className="star-rating"
      onMouseLeave={handleMouseLeave}
      aria-label={`Rating: ${value} out of ${maxStars}`}
    >
      {Array.from({length: maxStars}, (_, index) => {
        const starNumber = index + 1
        return (
          <StarButton
            key={starNumber}
            starNumber={starNumber}
            color={getStarColor(starNumber)}
            onClick={() => handleStarClick(starNumber)}
            onMouseEnter={() => handleMouseEnter(starNumber)}
          />
        )
      })}
      <span className="star-rating__value">{value || 0}</span>
    </div>
  )
}

// Step 2: Define it for FormEngine with data binding
export const starRating = define(StarRating, 'StarRating')
  .props({
    // This is the KEY prop - it enables data binding!
    value: number
      .valued, // ← This makes it a valued property!

    // Regular props (no data binding)
    maxStars: number.default(5),
    activeColor: string.default('#FFD700'),
    inactiveColor: string.default('#DDDDDD')
  })
  .build()

Using the Rating Component

{
  "key": "productRating",
  "type": "StarRating",
  "props": {
    "maxStars": {
      "value": 5
    },
    "activeColor": {
      "value": "#FFD700"
    }
  }
}

Live Example

live

function App() {
  const Star = ({color}) => (
    <svg
      width="24"
      height="24"
      viewBox="0 0 24 24"
      fill={color}
      stroke={color}
      strokeWidth="1"
    >
      <path d="M12 2l3.09 6.26L22 9.27l-5 4.87 1.18 6.88L12 17.77l-6.18 3.25L7 14.14 2 9.27l6.91-1.01L12 2z"/>
    </svg>
  )

  const StarButton = ({
                        starNumber,
                        color,
                        onClick,
                        onMouseEnter
                      }) => {
    return <button
      type="button"
      className="star-rating__star"
      onClick={onClick}
      onMouseEnter={onMouseEnter}
      aria-label={`Rate ${starNumber} star${starNumber > 1 ? 's' : ''}`}
    >
      <Star color={color}/>
    </button>
  }

  const StarRating = ({
                        value,
                        onChange,
                        maxStars,
                        activeColor,
                        inactiveColor
                      }) => {
    const [hoveredStar, setHoveredStar] = useState(null)

    const handleStarClick = (starValue) => {
      onChange?.(starValue)
    }

    const handleMouseEnter = (starValue) => {
      setHoveredStar(starValue)
    }

    const handleMouseLeave = () => {
      setHoveredStar(null)
    }

    const getStarColor = (starIndex) => {
      const effectiveRating = hoveredStar || value
      return starIndex <= effectiveRating ? activeColor : inactiveColor
    }

    return (
      <div
        className="star-rating"
        onMouseLeave={handleMouseLeave}
        aria-label={`Rating: ${value} out of ${maxStars}`}
      >
        {Array.from({length: maxStars}, (_, index) => {
          const starNumber = index + 1
          return (
            <StarButton
              key={starNumber}
              starNumber={starNumber}
              color={getStarColor(starNumber)}
              onClick={() => handleStarClick(starNumber)}
              onMouseEnter={() => handleMouseEnter(starNumber)}
            />
          )
        })}
        <span className="star-rating__value">{value || 0}</span>
      </div>
    )
  }

  const starRating = define(StarRating, 'StarRating')
    .props({
      value: number.valued,
      maxStars: number.default(5),
      activeColor: string.default('#FFD700'),
      inactiveColor: string.default('#DDDDDD')
    })
    .build()

  const view = createView([starRating.model])

  const formJson = {
    "form": {
      "key": "Screen",
      "type": "Screen",
      "children": [
        {
          "key": "productRating",
          "type": "StarRating",
          "props": {
            "maxStars": {
              "value": 5
            },
            "activeColor": {
              "value": "#FFD700"
            }
          }
        }
      ]
    }
  }

  return (
    <FormViewer
      view={view}
      getForm={() => JSON.stringify(formJson)}
      onFormDataChange={({data}) => {
        console.log(JSON.stringify(data))
      }}
    />
  )
}

What happens:

Component renders with current value from form data (or 0 if not set)
User clicks on stars → onChange is called with new value
FormEngine automatically updates form.data.productRating
Validation runs if configured
Component re-renders with new value

Understanding the .valued Property

The .valued modifier is what transforms a regular prop into a data-bound prop:

// Regular prop - just passes a value
regularProp: string

// Valued prop - connects to form data
valuedProp: string.valued

// Valued prop with uncontrolled behavior
uncontrolledProp: string.valued.uncontrolledValue('default')

How .valued Changes Behavior

Feature	Regular Prop	Valued Prop
Gets value from	Props	Form data store
Updates trigger	Nothing	Form data update
Validates	No	Yes
Tracks dirty state	No	Yes
Available in form data	No	Yes

Valued Property Types

String Valued Props

const CustomInput = ({value, onChange, placeholder}: any) => (
  <input
    value={value}
    onChange={e => onChange(e.target.value)}
    placeholder={placeholder}
  />
)

export const customInput = define(CustomInput, 'CustomInput')
  .props({
    value: string
      .valued
      .uncontrolledValue(''),

    placeholder: string.default('Enter text...')
  })
  .build()

Live Example

live

function App() {
  const CustomInput = ({value, onChange, placeholder}) => (
    <input
      value={value}
      onChange={e => onChange(e.target.value)}
      placeholder={placeholder}
    />
  )

  const customInput = define(CustomInput, 'CustomInput')
    .props({
      value: string
        .valued
        .uncontrolledValue(''),

      placeholder: string.default('Enter text...')
    })
    .build()

  const view = createView([customInput.model])

  const formJson = {
    "form": {
      "key": "Screen",
      "type": "Screen",
      "children": [
        {
          "key": "customInput",
          "type": "CustomInput"
        }
      ]
    }
  }

  return (
    <FormViewer
      view={view}
      getForm={() => JSON.stringify(formJson)}
      onFormDataChange={({data}) => {
        console.log(JSON.stringify(data))
      }}
    />
  )
}

What happens:

Component renders with current value from form data (or 0 if not set)
User clicks on stars → onChange is called with new value
FormEngine automatically updates form.data.productRating
Validation runs if configured
Component re-renders with new value

Number Valued Props

const NumberSpinner = ({value = 0, onChange, min, max}: any) => {
  const increment = () => onChange(Math.min(value + 1, max))
  const decrement = () => onChange(Math.max(value - 1, min))

  return (
    <div className="number-spinner">
      <button onClick={decrement}>-</button>
      <span>{value}</span>
      <button onClick={increment}>+</button>
    </div>
  )
}

export const numberSpinner = define(NumberSpinner, 'NumberSpinner')
  .props({
    value: number.valued,
    min: number.default(0),
    max: number.default(100)
  })
  .build()

Live Example

live

function App() {
  const NumberSpinner = ({value = 0, onChange, min, max}) => {
    const increment = () => onChange(Math.min(value + 1, max))
    const decrement = () => onChange(Math.max(value - 1, min))

    return (
      <div className="number-spinner">
        <button onClick={decrement}>-</button>
        <span>{value}</span>
        <button onClick={increment}>+</button>
      </div>
    )
  }

  const numberSpinner = define(NumberSpinner, 'NumberSpinner')
    .props({
      value: number.valued,
      min: number.default(0),
      max: number.default(100)
    })
    .build()

  const view = createView([numberSpinner.model])

  const formJson = {
    "form": {
      "key": "Screen",
      "type": "Screen",
      "children": [
        {
          "key": "numberSpinner",
          "type": "NumberSpinner"
        }
      ]
    }
  }

  return (
    <FormViewer
      view={view}
      getForm={() => JSON.stringify(formJson)}
      onFormDataChange={({data}) => {
        console.log(JSON.stringify(data))
      }}
    />
  )
}

Boolean Valued Props

const ToggleSwitch = ({value, onChange, label}: any) => (
  <label className="toggle-switch">
    <span>{label}</span>
    <input
      type="checkbox"
      checked={value}
      onChange={e => onChange(e.target.checked)}
    />
    <span className="toggle-switch__slider"/>
  </label>
)

export const toggleSwitch = define(ToggleSwitch, 'ToggleSwitch')
  .props({
    value: boolean.valued.uncontrolledValue(false),
    label: string.default('Enable feature')
  })
  .build()

Live Example

live

function App() {
  const ToggleSwitch = ({value, onChange, label}) => (
    <label className="toggle-switch">
      <span>{label}</span>
      <input
        type="checkbox"
        checked={value}
        onChange={e => onChange(e.target.checked)}
      />
      <span className="toggle-switch__slider"/>
    </label>
  )

  const toggleSwitch = define(ToggleSwitch, 'ToggleSwitch')
    .props({
      value: boolean.valued.uncontrolledValue(false),
      label: string.default('Enable feature')
    })
    .build()

  const view = createView([toggleSwitch.model])

  const formJson = {
    "form": {
      "key": "Screen",
      "type": "Screen",
      "children": [
        {
          "key": "toggleSwitch",
          "type": "ToggleSwitch"
        }
      ]
    }
  }

  return (
    <FormViewer
      view={view}
      getForm={() => JSON.stringify(formJson)}
      onFormDataChange={({data}) => {
        console.log(JSON.stringify(data))
      }}
    />
  )
}

Array Valued Props

const MultiSelect = ({value = [], onChange, options}: any) => {
  const handleToggle = (optionValue) => {
    const newValue = value.includes(optionValue)
      ? value.filter(v => v !== optionValue)
      : [...value, optionValue]
    onChange(newValue)
  }

  return (
    <div className="multi-select">
      {options.map(option => (
        <label key={option.value}>
          <input
            type="checkbox"
            checked={value.includes(option.value)}
            onChange={() => handleToggle(option.value)}
          />
          {option.label}
        </label>
      ))}
    </div>
  )
}

export const multiSelect = define(MultiSelect, 'MultiSelect')
  .props({
    value: array.valued,
    options: array
      .default([
        {value: 'option1', label: 'Option 1'},
        {value: 'option2', label: 'Option 2'}
      ])
  })
  .build()

Live Example

live

function App() {
  const MultiSelect = ({value = [], onChange, options}) => {
    const handleToggle = (optionValue) => {
      const newValue = value.includes(optionValue)
        ? value.filter(v => v !== optionValue)
        : [...value, optionValue]
      onChange(newValue)
    }

    return (
      <div className="multi-select">
        {options.map(option => (
          <label key={option.value}>
            <input
              type="checkbox"
              checked={value.includes(option.value)}
              onChange={() => handleToggle(option.value)}
            />
            {option.label}
          </label>
        ))}
      </div>
    )
  }

  const multiSelect = define(MultiSelect, 'MultiSelect')
    .props({
      value: array.valued,
      options: array
        .default([
          {value: 'option1', label: 'Option 1'},
          {value: 'option2', label: 'Option 2'}
        ])
    })
    .build()

  const view = createView([multiSelect.model])

  const formJson = {
    "form": {
      "key": "Screen",
      "type": "Screen",
      "children": [
        {
          "key": "multiSelect",
          "type": "MultiSelect"
        }
      ]
    }
  }

  return (
    <FormViewer
      view={view}
      getForm={() => JSON.stringify(formJson)}
      onFormDataChange={({data}) => {
        console.log(JSON.stringify(data))
      }}
    />
  )
}

Advanced Data Binding Patterns

Uncontrolled Valued Props

If the valued component must have a value other than undefined, then add an uncontrolledValue, then FormEngine will substitute the value from uncontrolledValue instead of undefined.

const DebouncedInput = ({value, onChange, delay}: any) => {
  const [internalValue, setInternalValue] = useState(value)

  useEffect(() => {
    const timeout = setTimeout(() => {
      onChange(internalValue)
    }, delay)

    return () => clearTimeout(timeout)
  }, [internalValue, delay, onChange])

  return (
    <input
      value={internalValue}
      onChange={e => setInternalValue(e.target.value)}
    />
  )
}

export const debouncedInput = define(DebouncedInput, 'DebouncedInput')
  .props({
    value: string
      .valued
      .uncontrolledValue(''), // Component manages initial state

    delay: number.default(300)
  })
  .build()

Live Example

live

function App() {
  const DebouncedInput = ({value, onChange, delay}) => {
    const [internalValue, setInternalValue] = useState(value)

    useEffect(() => {
      const timeout = setTimeout(() => {
        onChange(internalValue)
      }, delay)

      return () => clearTimeout(timeout)
    }, [internalValue, delay, onChange])

    return (
      <input
        value={internalValue}
        onChange={e => setInternalValue(e.target.value)}
      />
    )
  }

  const debouncedInput = define(DebouncedInput, 'DebouncedInput')
    .props({
      value: string
        .valued
        .uncontrolledValue(''), // Component manages initial state

      delay: number.default(300)
    })
    .build()

  const view = createView([debouncedInput.model])

  const formJson = {
    "form": {
      "key": "Screen",
      "type": "Screen",
      "children": [
        {
          "key": "debouncedInput",
          "type": "DebouncedInput"
        }
      ]
    }
  }

  return (
    <FormViewer
      view={view}
      getForm={() => JSON.stringify(formJson)}
      onFormDataChange={({data}) => {
        console.log(JSON.stringify(data))
      }}
    />
  )
}

Validation Integration

Valued components automatically participate in validation:

const AgeInput = ({value = 0, onChange}: any) => (
  <input
    type="number"
    value={value}
    onChange={e => onChange(Number(e.target.value))}
    min="0"
    max="150"
  />
)

export const ageInput = define(AgeInput, 'AgeInput')
  .props({
    value: number.valued
  })
  .build()

Live Example

live

function App() {
  const AgeInput = ({value = 0, onChange}) => (
    <input
      type="number"
      value={value}
      onChange={e => onChange(Number(e.target.value))}
      min="0"
      max="150"
    />
  )

  const ageInput = define(AgeInput, 'AgeInput')
    .props({
      value: number.valued
    })
    .build()

  const view = createView([ageInput.model])

  const formJson = {
    "form": {
      "key": "Screen",
      "type": "Screen",
      "children": [
        {
          "key": "ageInput",
          "type": "AgeInput",
          "schema": {
            "validations": [
              {
                "key": "min",
                "args": {
                  "limit": 0
                }
              },
              {
                "key": "max",
                "args": {
                  "limit": 10
                }
              }
            ]
          }
        }
      ]
    }
  }

  return (
    <FormViewer
      view={view}
      getForm={() => JSON.stringify(formJson)}
      onFormDataChange={({data}) => {
        console.log(JSON.stringify(data))
      }}
    />
  )
}

Real-World Example: Color Picker

const ColorPicker = ({value = '#000000', onChange, presetColors = []}: any) => {
  const [showCustom, setShowCustom] = useState(false)
  const [customColor, setCustomColor] = useState('#000000')

  const colors = presetColors.length > 0 ? presetColors : [
    '#FF6B6B', '#4ECDC4', '#45B7D1', '#96CEB4', '#FFEAA7',
    '#DDA0DD', '#98D8C8', '#F7DC6F', '#BB8FCE', '#85C1E9'
  ]

  const handleColorSelect = (color) => {
    onChange(color)
    setShowCustom(false)
  }

  const handleCustomColor = () => {
    onChange(customColor)
    setShowCustom(false)
  }

  return (
    <div className="color-picker" style={{display: 'flex', flexDirection: 'column', gap: 5, maxWidth: 200}}>
      <div className="color-picker__grid" style={{display: 'flex', gap: 5}}>
        {colors.map(color => (
          <button
            key={color}
            className={`color-picker__swatch ${value === color ? 'is-selected' : ''}`}
            style={{backgroundColor: color, height: 35, width: 40, border: 'none', borderRadius: 10}}
            onClick={() => handleColorSelect(color)}
            aria-label={`Select color ${color}`}
          />
        ))}
      </div>

      <button
        className="color-picker__custom-btn"
        onClick={() => setShowCustom(!showCustom)}
      >
        Custom Color
      </button>

      {showCustom && (
        <div className="color-picker__custom">
          <input
            type="color"
            value={customColor}
            onChange={e => setCustomColor(e.target.value)}
          />
          <button onClick={handleCustomColor}>Apply</button>
        </div>
      )}

      <div className="color-picker__selected">
        Selected: <span style={{color: value}}>{value}</span>
      </div>
    </div>
  )
}

export const colorPicker = define(ColorPicker, 'ColorPicker')
  .props({
    value: string.valued,
    presetColors: array
      .default([
        '#FF6B6B', '#4ECDC4', '#45B7D1', '#96CEB4', '#FFEAA7'
      ])
  })
  .build()

Usage in Form:

{
  "key": "favoriteColor",
  "type": "ColorPicker",
  "props": {
    "presetColors": {
      "value": [
        "#FF0000",
        "#00FF00",
        "#0000FF",
        "#FFFF00",
        "#FF00FF"
      ]
    }
  }
}

Live Example

live

function App() {
  const ColorPicker = ({value = '#000000', onChange, presetColors = []}) => {
    const [showCustom, setShowCustom] = useState(false)
    const [customColor, setCustomColor] = useState('#000000')

    const colors = presetColors.length > 0 ? presetColors : [
      '#FF6B6B', '#4ECDC4', '#45B7D1', '#96CEB4', '#FFEAA7',
      '#DDA0DD', '#98D8C8', '#F7DC6F', '#BB8FCE', '#85C1E9'
    ]

    const handleColorSelect = (color) => {
      onChange(color)
      setShowCustom(false)
    }

    const handleCustomColor = () => {
      onChange(customColor)
      setShowCustom(false)
    }

    return (
      <div className="color-picker" style={{display: 'flex', flexDirection: 'column', gap: 5, maxWidth: 200}}>
        <div className="color-picker__grid" style={{display: 'flex', gap: 5}}>
          {colors.map(color => (
            <button
              key={color}
              className={`color-picker__swatch ${value === color ? 'is-selected' : ''}`}
              style={{backgroundColor: color, height: 35, width: 40, border: 'none', borderRadius: 10}}
              onClick={() => handleColorSelect(color)}
              aria-label={`Select color ${color}`}
            />
          ))}
        </div>

        <button
          className="color-picker__custom-btn"
          onClick={() => setShowCustom(!showCustom)}
        >
          Custom Color
        </button>

        {showCustom && (
          <div className="color-picker__custom">
            <input
              type="color"
              value={customColor}
              onChange={e => setCustomColor(e.target.value)}
            />
            <button onClick={handleCustomColor}>Apply</button>
          </div>
        )}

        <div className="color-picker__selected">
          Selected: <span style={{color: value}}>{value}</span>
        </div>
      </div>
    )
  }

  const colorPicker = define(ColorPicker, 'ColorPicker')
    .props({
      value: string.valued,
      presetColors: array
        .default([
          '#FF6B6B', '#4ECDC4', '#45B7D1', '#96CEB4', '#FFEAA7'
        ])
    })
    .build()

  const view = createView([colorPicker.model])

  const formJson = {
    "form": {
      "key": "Screen",
      "type": "Screen",
      "children": [
        {
          "key": "favoriteColor",
          "type": "ColorPicker",
          "props": {
            "presetColors": {
              "value": [
                "#FF0000",
                "#00FF00",
                "#0000FF",
                "#FFFF00",
                "#FF00FF"
              ]
            }
          }
        }
      ]
    }
  }

  return (
    <FormViewer
      view={view}
      getForm={() => JSON.stringify(formJson)}
      onFormDataChange={({data}) => {
        console.log(JSON.stringify(data))
      }}
    />
  )
}

Testing Valued Components

describe('StarRating', () => {
  afterEach(() => {
    cleanup()
  })

  test('renders with initial value', () => {
    const onChange = vi.fn()
    const {getByLabelText} = render(
      <StarRating value={3} onChange={onChange} maxStars={5}/>
    )

    expect(getByLabelText('Rating: 3 out of 5')).toBeInTheDocument()
  })

  test('calls onChange when star is clicked', () => {
    const onChange = vi.fn()
    const {getByLabelText} = render(
      <StarRating value={0} onChange={onChange} maxStars={10}/>
    )

    fireEvent.click(getByLabelText('Rate 3 stars'))
    expect(onChange).toHaveBeenCalledWith(3)
  })

  test('respects maxStars prop', () => {
    const onChange = vi.fn()
    const {queryByLabelText} = render(
      <StarRating value={0} onChange={onChange} maxStars={3}/>
    )

    expect(queryByLabelText('Rate 4 stars')).not.toBeInTheDocument()
  })
})

Common Patterns

Pattern 1: Input with Clear Button

const ClearableInput = ({value, onChange, placeholder}: any) => {
  const handleClear = () => onChange(undefined)

  return (
    <div className="clearable-input">
      <input
        value={value}
        onChange={e => onChange(e.target.value)}
        placeholder={placeholder}
      />
      {value && (
        <button
          type="button"
          onClick={handleClear}
          aria-label="Clear input"
        >
          ✕
        </button>
      )}
    </div>
  )
}

export const clearableInput = define(ClearableInput, 'ClearableInput')
  .props({
    value: string.valued.uncontrolledValue(''),
    placeholder: string.default('Enter text...')
  })
  .build()

Live Example

live

function App() {
  const ClearableInput = ({value, onChange, placeholder}) => {
    const handleClear = () => onChange(undefined)

    return (
      <div className="clearable-input">
        <input
          value={value}
          onChange={e => onChange(e.target.value)}
          placeholder={placeholder}
        />
        {value && (
          <button
            type="button"
            onClick={handleClear}
            aria-label="Clear input"
          >
            ✕
          </button>
        )}
      </div>
    )
  }

  const clearableInput = define(ClearableInput, 'ClearableInput')
    .props({
      value: string.valued.uncontrolledValue(''),
      placeholder: string.default('Enter text...')
    })
    .build()

  const view = createView([clearableInput.model])

  const formJson = {
    "form": {
      "key": "Screen",
      "type": "Screen",
      "children": [
        {
          "key": "clearableInput",
          "type": "ClearableInput"
        }
      ]
    }
  }

  return (
    <FormViewer
      view={view}
      getForm={() => JSON.stringify(formJson)}
      onFormDataChange={({data}) => {
        console.log(JSON.stringify(data))
      }}
    />
  )
}

Pattern 2: Toggle Group

const ToggleGroup = ({value, onChange, options}: any) => (
  <div className="toggle-group" style={{display: 'flex', gap: 5}}>
    {options.map(option => (
      <button
        key={option.value}
        type="button"
        className={`toggle-group__item ${value === option.value ? 'is-active' : ''}`}
        style={{backgroundColor: value === option.value ? 'lightblue' : 'lightgray'}}
        onClick={() => onChange(option.value)}
      >
        {option.label}
      </button>
    ))}
  </div>
)

export const toggleGroup = define(ToggleGroup, 'ToggleGroup')
  .props({
    value: string.valued,
    options: array.default([
      {value: 'yes', label: 'Yes'},
      {value: 'no', label: 'No'}
    ])
  })
  .build()

Live Example

live

function App() {
  const ToggleGroup = ({value, onChange, options}) => (
    <div className="toggle-group" style={{display: 'flex', gap: 5}}>
      {options.map(option => (
        <button
          key={option.value}
          type="button"
          className={`toggle-group__item ${value === option.value ? 'is-active' : ''}`}
          style={{backgroundColor: value === option.value ? 'lightblue' : 'lightgray'}}
          onClick={() => onChange(option.value)}
        >
          {option.label}
        </button>
      ))}
    </div>
  )

  const toggleGroup = define(ToggleGroup, 'ToggleGroup')
    .props({
      value: string.valued,
      options: array.default([
        {value: 'yes', label: 'Yes'},
        {value: 'no', label: 'No'}
      ])
    })
    .build()

  const view = createView([toggleGroup.model])

  const formJson = {
    "form": {
      "key": "Screen",
      "type": "Screen",
      "children": [
        {
          "key": "toggleGroup",
          "type": "ToggleGroup"
        }
      ]
    }
  }

  return (
    <FormViewer
      view={view}
      getForm={() => JSON.stringify(formJson)}
      onFormDataChange={({data}) => {
        console.log(JSON.stringify(data))
      }}
    />
  )
}

Overriding existing event handlers

Sometimes you need to work with third-party components that have different onChange event handler signatures. For example, some components pass the event object as the first parameter instead of the value. FormEngine Core provides a way to handle this through the overrideEventHandlers function.

When to Use overrideEventHandlers

Use overrideEventHandlers when:

A component’s onChange handler receives an event object instead of a value
You need to extract the value from a complex event object
The component uses non-standard event names (e.g., onSelect instead of onChange)
You need to transform the event data before it reaches the form store

Built-in Event Handlers in FormEngine Core

FormEngine Core currently provides two built-in event handlers:

onChange - Triggered when a component’s value changes
onBlur - Triggered when a component loses focus

Example: Overriding onChange for Event Object

Below is an example of redefining the onChange and onBlur events for the Input component from the @mui/material library:

export const matInput = define(Input, 'MatInput')
  .name('Input')
  .props({
    value: string.valued.uncontrolledValue('')
  })
  .overrideEventHandlers({
    onChange: (e: ActionEventArgs) => {
      const value = e.args[0].target.value
      e.sender.field?.setValue(value)
    },
    // optional, to track the touched field property
    onBlur: (e: ActionEventArgs) => {
      e.sender.field?.setTouched()
    },
  })

Summary

Valued components are essential for creating interactive forms. Key points:

Use .valued to enable data binding
Components receive value and onChange props automatically
FormEngine handles store synchronization
Validation runs automatically
Supports all data types (string, number, boolean, array, object)

Next Steps:

Learn about Components with Events to handle user interactions
Check out Advanced Patterns for complex scenarios

Happy coding! 🎯

​What Are Valued Components?

​Understanding Data Binding

​Creating Your First Valued Component

​Example: Custom Rating Component

​Using the Rating Component

​Live Example

​Understanding the .valued Property

​How .valued Changes Behavior

​Valued Property Types

​String Valued Props

​Live Example

​Number Valued Props

​Live Example

​Boolean Valued Props

​Live Example

​Array Valued Props

​Live Example

​Advanced Data Binding Patterns

​Uncontrolled Valued Props

​Live Example

​Validation Integration

​Live Example

​Real-World Example: Color Picker

​Live Example

​Testing Valued Components

​Common Patterns

​Pattern 1: Input with Clear Button

​Live Example

​Pattern 2: Toggle Group

​Live Example

​Overriding existing event handlers

​When to Use overrideEventHandlers

​Built-in Event Handlers in FormEngine Core

​Example: Overriding onChange for Event Object

​Summary

What Are Valued Components?

Understanding Data Binding

Creating Your First Valued Component

Example: Custom Rating Component

Using the Rating Component

Live Example

Understanding the .valued Property

How .valued Changes Behavior

Valued Property Types

String Valued Props

Live Example

Number Valued Props

Live Example

Boolean Valued Props

Live Example

Array Valued Props

Live Example

Advanced Data Binding Patterns

Uncontrolled Valued Props

Live Example

Validation Integration

Live Example

Real-World Example: Color Picker

Live Example

Testing Valued Components

Common Patterns

Pattern 1: Input with Clear Button

Live Example

Pattern 2: Toggle Group

Live Example

Overriding existing event handlers

When to Use overrideEventHandlers

Built-in Event Handlers in FormEngine Core

Example: Overriding onChange for Event Object

Summary