Dropdown Card

This feature is only available in ESP-DASH Pro

A dashboard component that provides a selectable dropdown list with support for unlimited comma-separated choices. Enables users to make selections from a customizable list of options directly on their dashboard.

Initializer

To create a dropdown card in ESP-DASH v5, use the dash::DropdownCard<T, Precision> class. The template parameters allow you to control the value type and decimal precision:

T: Value type (e.g., int, float, dash::string, const char*)
Precision: Number of decimal places for floating point values (default: 2)

Example 1: String value (default)


dash::DropdownCard<dash::string> dropdown(dashboard, "Dropdown", "Option1,Option2,Option3");

Example 2: Float value, custom precision (3 decimals)


dash::DropdownCard<float, 3> dropdownFloat(dashboard, "Float Dropdown", "1.234,2.345,3.456");

Example 3: Integer value


dash::DropdownCard<int> dropdownInt(dashboard, "Int Dropdown", "1,2,3,4");

Callback


dropdown.onChange([](auto value) {
  // Handle dropdown selection
});

Methods

`setOptions(const char* options[], size_t count)`

Set the dropdown options.


dropdown.setOptions(options, 3);

Signature: void setOptions(const char* options[], size_t count)
Parameters:
- const char* options[] — Array of option strings.
- size_t count — Number of options.
Returns: void

`options()`

Get the current dropdown options.


const char* opts = dropdown.options();

Signature: const char* options()
Parameters: None
Returns: const char* — The current options as a comma-separated string.

`setValue(T value)`

Set the dropdown value. The type of value must match the template type you chose for T (e.g., int, float, dash::string, const char*).


dropdown.setValue(value); // value is of type T

Signature: void setValue(T value)
Parameters:
- T value — The value to select (type matches template parameter T).
Returns: void

`value()`

Get the currently selected value. The return type matches your template type for T (e.g., int, float, dash::string, const char*).


T v = dropdown.value();

Signature: T value()
Parameters: None
Returns: T — The currently selected value (type matches template parameter T).

Note:

T can be one of: int, float, dash::string, or const char* depending on how you instantiate the card.

Reference

Below is a reference code showing how to integrate this widget in a real project, including initialization and value updates usage.


// ...
 
// Create a dropdown card (string, default)
dash::DropdownCard<dash::string> dropdownCard(dashboard, "Dropdown", "Option1,Option2,Option3");
 
void setup() {
  // ...
  dropdownCard.setValue("Option1");
}
 
void loop() {
  // ...
}