Cascader

Chart style

The Cascader is a control widget that you can use as a cascading form in a visualization application. It submits the data that a user selects to the backend for processing. You can also configure interactions to display the user's selections in other widgets.

Configuration panel

• Search for Configurations: In the right-side panel of Canvas Editor, click the Settings tab, and click Search for Configurations in the upper-right corner. Enter the required configuration item in the search box, and click the search icon to quickly locate the configuration item. Fuzzy match is supported. For more information, see Search for Configurations.
• Size: indicates the size of a widget, including its pixel width and height. You can click the icon to proportionally adjust the width and height of a widget. After you click this icon again, you can adjust the width and height as needed.
• Position: the position of a widget, which is indicated by pixel X and Y coordinates. X-coordinate indicates the pixel distance between the upper-left corner of the widget and the left border of the canvas. Y-coordinate indicates the pixel distance between the upper-left corner of the widget and the upper border of the canvas.
• Rotation Angle: the angle of a rotation that uses the center point of a widget as the rotation point. The unit is degrees (°). You can use one of the following methods to control the rotation angle of a widget:
  • Directly enter the degrees in the Rotation Angle spin box or click the plus sign (+) or minus sign (-) to increase or decrease the value in the Rotation Angle spin box.
  • Drag the black dot in the icon.
  • Click the icon to horizontally flip a widget.
  • Click the icon to vertically flip a widget.
• Opacity: the opacity of a widget. Valid values: 0 and 1. If this parameter is set to 0, the widget is hidden. If this parameter is set to 1, the widget is completely displayed. Default value: 1.

• Input Box

  • Default Selection: You can enter the default selected path, with components separated by a comma (,), such as zhejiang,hangzhou,xihu.

  • Placeholder Text: Specifies the placeholder text in the input box. This text is displayed by default when no value is selected.

  • No Data Text: Specifies the text to display when the dropdown list is empty.

  • Enhanced Features: Specifies the enhanced features of the input box.

    Parameter	Description
    Dropdown Search	Turn on this switch to enable search in the input box. You can filter the dropdown list. Turn off this switch to disable this feature.
    Clear Selection	Turn on this switch to show a clear icon on mouseover when the input box has a value. Click the icon to clear the content of the input box. Turn off this switch to disable this feature.
    Take effect immediately	Turn on this switch to update the input box in real time when an item is selected from the dropdown list. Turn off this switch to disable this feature.
    Disable	Turn on this switch to disable the cascader. Turn off this switch to use the cascader.

  • Background Color: Specifies the background color of the cascader.

  • Border Style: Specifies the style of the cascader border. In the default style, you can set the border weight, line type, line color, border radius, and border shadow color.

  • Text Style: Specifies the style of the text in the cascader.

    Parameter	Description
    Text Margin	The margin to the left of the text in the cascader.
    Font Style	The font style of the text in the cascader, including the font family, font weight, font size, and font color.

  • Helper Buttons: Specifies the style of the helper buttons in the cascader, such as the dropdown arrow and the clear icon.

    Parameter	Description
    Size	The size of the helper buttons.
    Right Margin	The margin to the right of the helper buttons.
    Dropdown Arrow	Turn on this switch to set the color of the dropdown arrow. Turn off this switch to disable this setting.
    Clear Icon	The color and background color of the clear icon.

• Dropdown Box

  • Height: Specifies the height style of the dropdown box.

    Parameter	Description
    Container Height	The height of the entire dropdown list.
    Container Top Margin	The distance from the top of the dropdown container to the cascader, in px.

  • Background: Specifies the background color of the dropdown box.

  • Border: Specifies the style of the dropdown box border.

    Parameter	Description
    Weight	The weight of the dropdown box border.
    Type	The type of the dropdown box border. You can select Solid Line, Dashed Line, or Dotted Line.
    Color	The color of the dropdown box border.
    Radius	The border radius of the dropdown box. The value range is 0 to 360. A value of 0 creates a square. A value of 360 creates a circle.

  • Option Style: Specifies the style of the option text in the dropdown box.

    Parameter	Description
    Option Height	The height of the options in the dropdown box, in px.
    Text Style	The style of the option text, including the font family, font weight, font size, and font color.
    Text Color	The color of the option text on mouseover and when selected.
    Background Color	The background color of the options, including the default background color, the background color on mouseover, and the background color when selected.
    Rightwards Arrow	Right Margin: The margin to the right of the rightwards arrow. Size: The size of the rightwards arrow. Color: The color of the rightwards arrow.
    Submenu	The way a submenu expands. You can select Click or Mouseover.

Data panel

Field description

Table 1. Parameters

Parameter	Description
Controlled Mode	If you turn on the switch, data is not requested when a widget is initialized. Data requests are triggered only based on callback IDs or the method configured in Blueprint Editor. If you turn off the switch, data requests are automatically triggered. By default, the switch is turned off.
Auto Data Request	After you select the Auto Data Request check box, you can enable dynamic polling, and manually specify the polling interval. If you do not select this check box, data is not automatically requested. You must manually refresh the page to request data or use Blueprint Editor or callback ID events to trigger data requests.
Data Source	In the right-side panel of Canvas Editor, click the Data tab. Click Set next to Static Data. In the Configure Datasource panel, select a data source from the Data Source Type drop-down list. Enter code for data query in the code editor, click Preview Data Response to preview the response of the data source, and then view the response. For more information, see Configure asset data.
Data Filter	If you select the Data Filter check box, you can convert the data structure, filter data, and perform simple calculations. If you click the plus sign (+) next to Add Filter, you can configure the script for the data filter in the editor that appears. For more information, see Use the data filter.
Data Response Result	The response to a data request. If the data source changes, you can click the icon next to Data Response Result to view the data response in real time.

Interaction panel

You can select Enable on the right side of When an option is selected to enable the interaction feature. The Cascader widget has an interaction configuration. When an item is selected in the cascader, you can trigger a data request and pass a callback value. You can then use this value in other widgets. By default, the value configured on the Data panel is passed. For more information, see Configure a widget callback ID.

Blueprint editor interaction configuration

1. In Canvas Editor, right-click a widget in the Layer panel and select Add to Blueprint Editor.
2. Click the icon in the upper-left corner of the page.

3. On the blueprint editor configuration page, click the Cascader widget in the import node bar. The configuration parameters for the cascader in the blueprint editor appear on the canvas, as shown in the following figure.

   • Events

     Event	Description
     On Data API Request Completion	This event is triggered after a data API request is returned and processed by a filter. The processed data is passed in JSON format. For a data example, see the Data Response section on the Data tab of the widget's configuration panel in the canvas editor.
     When a data request fails	This event is triggered if a data API request fails and the response is processed by a filter. A request may fail due to network issues or API errors. The processed data is passed in JSON format. For a data example, see the Data Response section on the Data tab of the widget's configuration panel in the canvas editor.
     When an option is selected	This event is triggered when a dropdown option is selected. The data item that corresponds to the value is passed.

   • Actions

     Action	Description
     Request data API	Re-requests server-side data. Data from input data processing nodes or layer nodes is used as parameters. For example, if a cascade selector has its API data source set to https://api.test and the data passed to the Request data API action is { id: '1'}, the final API request is https://api.test?id=1.
     Import data API	Processes data in the component's drawing format, then imports the data to redraw the component. This action does not require re-requesting server-side data. For a data example, see the Data Response area on the Data tab in the component's configuration panel in the canvas editor.
     Set selected items	Sets the items currently selected in the cascade selector, such as ['zhejiang','hangzhou','xihu'].
     Clear selected items	Clears the values of the selected items in the cascade selector.
     Get current selection	Gets the value of the current selection in the cascade selector.
     Reset component to default	Resets the component to its default value.
     Update component configuration	Dynamically updates the style configuration of the component. First, click Copy Configuration to Clipboard in the component's Configuration panel to get the configuration data. Then, change the style field values as needed in the data processing node of the blueprint editor.
     Show	Shows the component. See the data example below. return { "animationType": "", "animationDuration": 1000, "animationEasing": "linear" };
     Hide	Hides the component. See the data example below. return { "animationType": "", "animationDuration": 1000, "animationEasing": "linear" };
     Toggle visibility	Toggles the component's visibility. See the data example below. return { "animationIn": { "animationType": "", "animationDuration": 1000, "animationEasing": "linear" }, "animationOut": { "animationType": "", "animationDuration": 1000, "animationEasing": "linear" } };
     Move	Moves the component to a specified position. See the data example below. return { // The movement method. Absolute: to. Relative: by. Default: to. "positionType": "to", // The specified position. x-coordinate, y-coordinate. "attr": { "x": 0, "y": 0 }, // The animation method. "animation": { "enable": false, // The animation duration. "animationDuration": 1000, // The animation curve. Optional values: linear, easeInOutQuad, or easeInOutExpo. "animationEasing": "linear" } };

Demo

This demo shows how to use the multi-selection feature of the Cascader to dynamically display a choropleth layer of city areas on a basic flat map.

1. Log on to the DataV console.

2. Select a visualization application and click Edit to go to the canvas editor page.

3. Add the Cascader widget and the Basic Flat Map widget to the canvas.

4. Click the Cascader, select the Data panel, and modify the static data.

   [
     {
       "value": "zhejiang",
       "label": "Zhejiang",
       "title": "Data to be connected",
       "lng": 120.0321621,
       "lat": 29.08208903,
       "adcode": "330000",
       "colorField": 1200,
       "children": [
         {
           "value": "hangzhou",
           "label": "Hangzhou",
           "title": "Data to be connected",
           "lng": 120.20903104,
           "lat": 30.2431451,
           "adcode": "330100",
           "colorField": 800,
           "children": [
             {
               "value": "xihu",
               "label": "Xihu",
               "title": "Data to be connected",
               "lng": 120.14492733,
               "lat": 30.23851003,
               "adcode": "330106",
               "colorField": 400
             }
           ]
         }
       ]
     },
     {
       "value": "guangdong",
       "label": "Guangdong",
       "title": "Data to be connected",
       "lng": 113.48155805,
       "lat": 23.18033886,
       "adcode": "440000",
       "colorField": 1200,
       "children": [
         {
           "value": "guangzhou",
           "label": "Guangzhou",
           "title": "Data to be connected",
           "lng": 113.26548282,
           "lat": 23.11906084,
           "adcode": "440100",
           "colorField": 800,
           "children": [
             {
               "value": "huangpu",
               "label": "Huangpu",
               "title": "Data to be connected",
               "lng": 113.8141788,
               "lat": 23.25787215,
               "adcode": "440112",
               "colorField": 400
             }
           ]
         }
       ]
     }
   ]

5. Right-click the widgets to import the Cascader, Basic Flat Map, and Choropleth Layer into the blueprint editor.

6. Connect the widgets as shown in the following figure.

7. Configure the processing methods for the serial data processing nodes.

   • Set the display position

     return {
       zoom: 8,// Set the map zoom level
       lng: data[data.length - 1].lng,// Display the longitude of the last city
       lat: data[data.length - 1].lat,// Display the latitude of the last city
       duration: 0.25// Set the map response interval
     }

   • Target Choropleth Layer

     return [
       {
         "colorField": data[data.length - 1].colorField,
         "adcode": data[data.length - 1].adcode
       }]

8. Click the icon in the upper-right corner of the page to preview the results.