Icon and Device Class Getter Migration

Mar 12, 2026

The get_icon_ref(), get_icon(), get_device_class_ref(), and get_device_class() methods are deprecated on all platforms and replaced by new buffer-based APIs get_icon_to() and get_device_class_to(). On ESP8266, the old methods produce a static_assert error because the underlying strings have been moved to PROGMEM and cannot be accessed through normal C string pointers. On other platforms, the old methods continue to work but emit deprecation warnings and will be removed in 2026.9.0.

This is a breaking change for external components in ESPHome 2026.3.0 and later.

Background

PR #14171: Pack entity string properties into PROGMEM-indexed fields PR #14437: Move icon strings to PROGMEM on ESP8266 PR #14443: Move device class strings to PROGMEM on ESP8266

Icon and device class strings are set at compile time and never change. PR #14171 packed these properties into PROGMEM-indexed uint8_t fields on EntityBase, replacing per-entity const char* pointers and the EntityBase_DeviceClass/EntityBase_UnitOfMeasurement mixin classes. Most entity types already had device_class and unit_of_measurement on the entity itself — the exception was NumberTraits, which previously inherited the mixin classes. NumberTraits no longer provides these accessors; use number->get_device_class_ref() / number->get_unit_of_measurement_ref() instead of number->traits.get_*_ref().

The old getter methods returned references or pointers to these strings, which required them to be stored as regular C strings in RAM. The new buffer-based APIs copy the string into a caller-provided buffer, which works regardless of where the string is stored.

On ESP8266, PRs #14437 and #14443 also move the strings into PROGMEM (flash), freeing valuable heap RAM. Since PROGMEM strings cannot be accessed through normal C string pointers on ESP8266, the old methods produce a hard static_assert error on that platform rather than a deprecation warning.

What’s Changing

Deprecated methods (all platforms, removal 2026.9.0)

Method	Replacement
`get_icon_ref()`	`get_icon_to(buffer)`
`get_icon()`	`get_icon_to(buffer)`
`get_device_class_ref()`	`get_device_class_to(buffer)`
`get_device_class()`	`get_device_class_to(buffer)`

NumberTraits: device_class and unit_of_measurement moved to entity

NumberTraits no longer provides get_device_class(), get_device_class_ref(), or get_unit_of_measurement_ref(). These are now accessed directly on the Number entity, consistent with all other entity types:

Before	After
`number->traits.get_device_class()`	`number->get_device_class_to(buffer)`
`number->traits.get_device_class_ref()`	`number->get_device_class_to(buffer)`
`number->traits.get_unit_of_measurement_ref()`	`number->get_unit_of_measurement_ref()`

EntityBase setters removed and packed into configure_entity_()

The following EntityBase setters have been removed and packed into the existing configure_entity_() call:

set_name()
set_icon()
set_device_class()
set_unit_of_measurement()
set_internal()
set_disabled_by_default()
set_entity_category()

Additionally, set_device() has been renamed to set_device_() and made protected.

These were codegen-only setters — calling them at runtime was unsafe and could silently corrupt state or crash the device (undefined behavior). If you were calling set_icon() from lambdas to dynamically change icons at runtime, move the icon logic to the Home Assistant side (e.g., using template sensors with icon templates).

See PR #14171, PR #14437, PR #14443, and PR #14564.

ESP8266-specific

On ESP8266, using any of the deprecated methods produces a static_assert error at compile time — they cannot work because the underlying strings are in PROGMEM.

New APIs

// Icon — copies into buffer, returns pointer to buffer (or nullptr if no icon set)
char icon_buf[MAX_ICON_LENGTH];
const char *icon = entity->get_icon_to(icon_buf);

// Device class — same pattern
char dc_buf[MAX_DEVICE_CLASS_LENGTH];
const char *dc = entity->get_device_class_to(dc_buf);

MAX_ICON_LENGTH and MAX_DEVICE_CLASS_LENGTH are both 64 bytes (63 characters + null terminator). Strings longer than 63 characters will produce a compile-time error.

Who This Affects

External components that:

Call get_icon_ref(), get_icon(), get_device_class_ref(), or get_device_class() on any entity — deprecation warning on all platforms, hard compile error on ESP8266
Access device_class or unit_of_measurement through NumberTraits — moved to Number entity directly
Call set_icon(), set_device_class(), set_unit_of_measurement(), or other removed EntityBase setters at runtime

Standard YAML configurations are not affected.

Migration Guide

Entity base migration

// Before
const auto &icon = entity->get_icon_ref();
const auto &dc = entity->get_device_class_ref();

// After
char icon_buf[MAX_ICON_LENGTH];
const char *icon = entity->get_icon_to(icon_buf);

char dc_buf[MAX_DEVICE_CLASS_LENGTH];
const char *dc = entity->get_device_class_to(dc_buf);

NumberTraits migration

// Before — accessed through traits (only Number had this pattern)
auto dc = number->traits.get_device_class();       // or get_device_class_ref()
auto uom = number->traits.get_unit_of_measurement_ref();

// After — accessed directly on entity, consistent with all other entity types
char dc_buf[MAX_DEVICE_CLASS_LENGTH];
const char *dc = number->get_device_class_to(dc_buf);
const auto &uom = number->get_unit_of_measurement_ref();

Checking if icon/device class is set

// Before
const auto &icon = entity->get_icon_ref();
if (!icon.empty()) {
  // use icon
}

// After
char icon_buf[MAX_ICON_LENGTH];
const char *icon = entity->get_icon_to(icon_buf);
if (icon != nullptr) {
  // use icon
}

Supporting Multiple ESPHome Versions

#if ESPHOME_VERSION_CODE >= VERSION_CODE(2026, 3, 0)
  char icon_buf[MAX_ICON_LENGTH];
  const char *icon = entity->get_icon_to(icon_buf);
#else
  const auto &icon = entity->get_icon_ref();
#endif

Timeline

ESPHome 2026.3.0 (March 2026): Old methods deprecated, static_assert on ESP8266, new buffer APIs available
ESPHome 2026.9.0 (September 2026): Old methods removed on all platforms

Finding Code That Needs Updates

# Find deprecated method usage
grep -rn 'get_icon_ref\|get_icon()' your_component/
grep -rn 'get_device_class_ref\|get_device_class()' your_component/

# Find NumberTraits accessors that moved to entity
grep -rn 'traits\.get_device_class\|traits\.get_unit_of_measurement' your_component/

# Find removed EntityBase setters
grep -rn 'set_icon\|set_device_class\|set_unit_of_measurement\|set_internal\|set_disabled_by_default\|set_entity_category\|set_name(' your_component/

Questions?

If you have questions about migrating your external component, please ask in:

ESPHome Discord - #devs channel
ESPHome GitHub Discussions

Comments

Feel free to leave a comment here to discuss this post with others. You can ask questions, share your experience, or suggest improvements. If you have a question about a specific feature or issue, please consider using the ESPHome Discord. Stick to English and follow ESPHome's code of conduct. These comments exist on a discussion on GitHub, so you can also comment there directly if you prefer.