Tutorial: All UI widgets demo

Important

This feature is in Public Preview.

This reference tutorial builds a Python UDF operator for Lakeflow Designer that exercises every UI widget available in the user-defined-operator-v0.1.0 schema. Use it as a template when creating your own operators. For a broader overview, see User-defined operators in Lakeflow Designer.

Overview

This operator is a demonstration UDF that accepts parameters using every available UI widget type. It concatenates all input values into a descriptive string, making it easy to see how each widget passes data to your function.

The available widget types are:

Widget Description Data Type
expression Column/expression picker from input port expression
input Single-line text input string
textarea Multi-line text area string
checkbox Checkbox toggle Boolean
toggle Switch toggle Boolean
number Number input with min/max number
slider Numeric slider with range number
select Single-select dropdown (static values) string
select Single-select dropdown (from input columns) string
multi-select Multi-select (static values) string[]
multi-select Multi-select (from input columns) string[]

Step 1: Write and test the Python function

First, define the Python function that accepts all the different parameter types. This function simply concatenates all inputs into a descriptive string for demonstration purposes.

def concat_all_widgets(
    # expression widget - column value from input
    expr_value: str,
    # input widget - single line text
    text_input: str,
    # textarea widget - multi line text
    text_area: str,
    # checkbox widget - boolean
    checkbox_flag: bool,
    # toggle widget - boolean
    toggle_flag: bool,
    # number widget - numeric input
    number_value: float,
    # slider widget - numeric slider
    slider_value: float,
    # select widget with static options
    select_static: str,
    # select widget with inputColumns options
    select_column: str,
    # multi-select widget with static options (array of strings)
    multi_select_static: list,
    # multi-select widget with inputColumns options (array of strings)
    multi_select_columns: list
) -> str:
    """
    Concatenates all input parameters into a descriptive string.
    This demonstrates all UI widget types available in user-defined operators.
    """
    lines = [
        f"1: Expression (Column Picker) -> {expr_value}",
        f"2: Text Input (Single Line) -> {text_input}",
        f"3: Text Area (Multi-Line) -> {text_area}",
        f"4: Checkbox Option -> {checkbox_flag}",
        f"5: Toggle Switch -> {toggle_flag}",
        f"6: Number Input -> {number_value}",
        f"7: Slider Value -> {slider_value}",
        f"8: Select (Static Options) -> {select_static}",
        f"9: Select (From Input Columns) -> {select_column}",
        f"10: Multi-Select (Static Options) -> [{', '.join(multi_select_static or [])}]",
        f"11: Multi-Select (From Input Columns) -> [{', '.join(multi_select_columns or [])}]"
    ]
    return "\n".join(lines)

Test the function with the following code:

result = concat_all_widgets(
    expr_value="column_value_123",
    text_input="Hello World",
    text_area="Line 1\nLine 2\nLine 3",
    checkbox_flag=True,
    toggle_flag=False,
    number_value=42.5,
    slider_value=75.0,
    select_static="option_b",
    select_column="amount",
    multi_select_static=["tag1", "tag3"],
    multi_select_columns=["col1", "col3"]
)
print(result)

Step 2: Create the YAML configuration

The YAML configuration defines how the operator appears in Lakeflow Designer. This example demonstrates every available widget type:

schema: user-defined-operator-v0.1.0
type: uc-udf
name: All Widgets Demo
id: demo.all_widgets
version: '1.0.0'
description: >
  A demonstration UDF that showcases all available UI widgets.
config:
  type: object
  properties:
    # ============================================
    # EXPRESSION WIDGET
    # ============================================
    expr_value:
      type: string
      format: expression
      title: 1. Expression (Column Picker)
      examples:
        - 'Select a column or enter an expression'
      x-ui:
        widget: expression
        port: in

    # ============================================
    # INPUT WIDGET (single-line text)
    # ============================================
    text_input:
      type: string
      title: 2. Text Input (Single Line)
      default: default text
      examples:
        - 'Enter a single line of text'
      x-ui:
        widget: input

    # ============================================
    # TEXTAREA WIDGET (multi-line text)
    # ============================================
    text_area:
      type: string
      title: 3. Text Area (Multi-Line)
      default: Sample text
      examples:
        - 'Enter multiple lines of text here...'
      x-ui:
        widget: textarea
        rows: 3

    # ============================================
    # CHECKBOX WIDGET (boolean)
    # ============================================
    checkbox_flag:
      type: boolean
      title: 4. Checkbox Option
      default: true
      x-ui:
        widget: checkbox

    # ============================================
    # TOGGLE WIDGET (boolean switch)
    # ============================================
    toggle_flag:
      type: boolean
      title: 5. Toggle Switch
      default: false
      x-ui:
        widget: toggle

    # ============================================
    # NUMBER WIDGET (numeric input with min/max)
    # ============================================
    number_value:
      type: number
      title: 6. Number Input
      default: 50
      minimum: 0
      maximum: 100
      examples:
        - 'Enter a number (0-100)'
      x-ui:
        widget: number

    # ============================================
    # SLIDER WIDGET (numeric slider)
    # ============================================
    slider_value:
      type: number
      title: 7. Slider Value
      default: 50
      minimum: 0
      maximum: 100
      x-ui:
        widget: slider
        step: 5

    # ============================================
    # SELECT WIDGET with STATIC options
    # ============================================
    select_static:
      type: string
      title: 8. Select (Static Options)
      default: option_a
      examples:
        - 'Choose an option'
      x-ui:
        widget: select
        optionsSource:
          type: static
          values:
            - option_a
            - option_b
            - option_c

    # ============================================
    # SELECT WIDGET with INPUT COLUMNS options
    # ============================================
    select_column:
      type: string
      title: 9. Select (From Input Columns)
      examples:
        - 'Select a column from input'
      x-ui:
        widget: select
        optionsSource:
          type: inputColumns
          port: in

    # ============================================
    # MULTI-SELECT WIDGET with STATIC options
    # ============================================
    multi_select_static:
      type: array
      items:
        type: string
      title: 10. Multi-Select (Static Options)
      default:
        - tag1
        - tag2
      examples:
        - 'Select one or more tags'
      x-ui:
        widget: multi-select
        optionsSource:
          type: static
          values:
            - tag1
            - tag2
            - tag3
            - tag4
            - tag5

    # ============================================
    # MULTI-SELECT WIDGET with INPUT COLUMNS options
    # ============================================
    multi_select_columns:
      type: array
      items:
        type: string
      title: 11. Multi-Select (From Input Columns)
      examples:
        - 'Select one or more columns'
      x-ui:
        widget: multi-select
        optionsSource:
          type: inputColumns
          port: in

  required:
    - expr_value
  additionalProperties: false
ports:
  input:
    - name: in
      title: Input Data
  output:
    - name: out
      title: Output

Schema highlights

Config Key Widget Data Type Purpose
expr_value expression expression Pick a column or expression from input data.
text_input input string Single-line text entry.
text_area textarea string Multi-line text entry.
checkbox_flag checkbox Boolean Boolean checkbox.
toggle_flag toggle Boolean Boolean toggle switch.
number_value number number Numeric input with min/max validation.
slider_value slider number Numeric slider with step increments.
select_static select string Dropdown with hardcoded options.
select_column select string Dropdown populated from input columns.
multi_select_static multi-select string[] Multi-select with hardcoded options.
multi_select_columns multi-select string[] Multi-select populated from input columns.

Options source types

For select and multi-select widgets, you must specify an optionsSource:

Static options — Fixed list of values:

optionsSource:
  type: static
  values:
    - value1
    - value2
    - value3

Input columns — Dynamic list from input port columns:

optionsSource:
  type: inputColumns
  port: in

See the User-defined operator YAML reference for a comprehensive guide to all available properties, data types, widgets, and options.

Step 3: Create the Unity Catalog function

Combine the YAML configuration and Python function into a single CREATE FUNCTION statement. Note that string[] (multi-select) values are passed as ARRAY<STRING> to the UDF.

CREATE OR REPLACE FUNCTION main.my_schema.all_widgets_demo(
    expr_value STRING,
    text_input STRING,
    text_area STRING,
    checkbox_flag BOOLEAN,
    toggle_flag BOOLEAN,
    number_value DOUBLE,
    slider_value DOUBLE,
    select_static STRING,
    select_column STRING,
    multi_select_static ARRAY<STRING>,
    multi_select_columns ARRAY<STRING>
)
RETURNS STRING
LANGUAGE PYTHON
AS $$
  """
  schema: user-defined-operator-v0.1.0
  type: uc-udf
  name: All Widgets Demo
  id: demo.all_widgets
  version: "1.0.0"
  description: >
    A demonstration UDF that showcases all available UI widgets.
  config:
    type: object
    properties:
      expr_value:
        type: string
        format: expression
        title: 1. Expression (Column Picker)
        examples:
          - "Select a column or enter an expression"
        x-ui:
          widget: expression
          port: in
      text_input:
        type: string
        title: 2. Text Input (Single Line)
        default: "default text"
        examples:
          - "Enter a single line of text"
        x-ui:
          widget: input
      text_area:
        type: string
        title: 3. Text Area (Multi-Line)
        default: Sample text
        examples:
          - "Enter multiple lines of text here..."
        x-ui:
          widget: textarea
          rows: 3
      checkbox_flag:
        type: boolean
        title: 4. Checkbox Option
        default: true
        x-ui:
          widget: checkbox
      toggle_flag:
        type: boolean
        title: 5. Toggle Switch
        default: false
        x-ui:
          widget: toggle
      number_value:
        type: number
        title: 6. Number Input
        default: 50
        minimum: 0
        maximum: 100
        examples:
          - "Enter a number (0-100)"
        x-ui:
          widget: number
      slider_value:
        type: number
        title: 7. Slider Value
        default: 50
        minimum: 0
        maximum: 100
        x-ui:
          widget: slider
          step: 5
      select_static:
        type: string
        title: 8. Select (Static Options)
        default: option_a
        examples:
          - "Choose an option"
        x-ui:
          widget: select
          optionsSource:
            type: static
            values:
              - option_a
              - option_b
              - option_c
      select_column:
        type: string
        title: 9. Select (From Input Columns)
        examples:
          - "Select a column from input"
        x-ui:
          widget: select
          optionsSource:
            type: inputColumns
            port: in
      multi_select_static:
        type: array
        items:
          type: string
        title: 10. Multi-Select (Static Options)
        default:
          - tag1
          - tag2
        examples:
          - "Select one or more tags"
        x-ui:
          widget: multi-select
          optionsSource:
            type: static
            values:
              - tag1
              - tag2
              - tag3
              - tag4
              - tag5
      multi_select_columns:
        type: array
        items:
          type: string
        title: 11. Multi-Select (From Input Columns)
        examples:
          - "Select one or more columns"
        x-ui:
          widget: multi-select
          optionsSource:
            type: inputColumns
            port: in
    required:
      - expr_value
    additionalProperties: false
  ports:
    input:
      - name: in
        title: Input Data
    output:
      - name: out
        title: Output
  """

  def concat_all_widgets(
      expr_value: str,
      text_input: str,
      text_area: str,
      checkbox_flag: bool,
      toggle_flag: bool,
      number_value: float,
      slider_value: float,
      select_static: str,
      select_column: str,
      multi_select_static: list,
      multi_select_columns: list
  ) -> str:
      lines = [
          f"1: Expression (Column Picker) -> {expr_value}",
          f"2: Text Input (Single Line) -> {text_input}",
          f"3: Text Area (Multi-Line) -> {text_area}",
          f"4: Checkbox Option -> {checkbox_flag}",
          f"5: Toggle Switch -> {toggle_flag}",
          f"6: Number Input -> {number_value}",
          f"7: Slider Value -> {slider_value}",
          f"8: Select (Static Options) -> {select_static}",
          f"9: Select (From Input Columns) -> {select_column}",
          f"10: Multi-Select (Static Options) -> [{', '.join(multi_select_static or [])}]",
          f"11: Multi-Select (From Input Columns) -> [{', '.join(multi_select_columns or [])}]"
      ]
      return "\n".join(lines)

  return concat_all_widgets(
      expr_value,
      text_input,
      text_area,
      checkbox_flag,
      toggle_flag,
      number_value,
      slider_value,
      select_static,
      select_column,
      multi_select_static,
      multi_select_columns
  )
$$

Step 4: Test the function

Test the UC function directly with SQL:

SELECT main.my_schema.all_widgets_demo(
    'my_column_value',             -- expr_value (expression)
    'Hello World',                 -- text_input (input)
    'Multi\nLine\nText',           -- text_area (textarea)
    TRUE,                          -- checkbox_flag (checkbox)
    FALSE,                         -- toggle_flag (toggle)
    42.5,                          -- number_value (number)
    75.0,                          -- slider_value (slider)
    'option_b',                    -- select_static (select with static)
    'amount',                      -- select_column (select with inputColumns)
    array('tag1', 'tag3'),         -- multi_select_static (multi-select with static)
    array('col1', 'col2', 'col3')  -- multi_select_columns (multi-select with inputColumns)
) AS result;

Step 5: Register the operator

Add the operator to your .user_defined_operators.yaml file:

operators:
  - catalog: main
    schema: my_schema
    functionName: all_widgets_demo

Step 6: Set up permissions

Grant access to users who need to use this operator:

GRANT USE SCHEMA ON SCHEMA main.my_schema TO `<user>`;
GRANT EXECUTE ON FUNCTION main.my_schema.all_widgets_demo TO `<user>`;

Using the operator in Lakeflow Designer

After it's registered, the operator will appear in Lakeflow Designer with a comprehensive configuration panel featuring:

  • An expression picker for column selection
  • Text inputs (single-line and multi-line)
  • Boolean controls (checkbox and toggle)
  • Numeric inputs (number field and slider)
  • Dropdowns with both static and dynamic options
  • Multi-select controls for choosing multiple values

This operator serves as a useful reference for understanding how each widget type renders and passes data to your function.

Widget reference summary

Widget Data Type UI Options
expression expression port (required), placeholder
input string placeholder
textarea string rows, placeholder
checkbox boolean placeholder
toggle boolean placeholder
number number min, max, placeholder
slider number min, max, step, placeholder
select string optionsSource (required), placeholder
multi-select string[] optionsSource (required), placeholder
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