Add target_temperature to the template water heater (#13661)

Co-authored-by: J. Nick Koston <nick@koston.org>

esphome/components/template/water_heater/__init__.py

@@ -46,6 +46,7 @@ CONFIG_SCHEMA = (
                 RESTORE_MODES, upper=True
             ),
             cv.Optional(CONF_CURRENT_TEMPERATURE): cv.returning_lambda,
+            cv.Optional(CONF_TARGET_TEMPERATURE): cv.returning_lambda,
             cv.Optional(CONF_MODE): cv.returning_lambda,
             cv.Optional(CONF_SUPPORTED_MODES): cv.ensure_list(
                 water_heater.validate_water_heater_mode
@@ -78,6 +79,14 @@ async def to_code(config: ConfigType) -> None:
         )
         cg.add(var.set_current_temperature_lambda(template_))
 
+    if CONF_TARGET_TEMPERATURE in config:
+        template_ = await cg.process_lambda(
+            config[CONF_TARGET_TEMPERATURE],
+            [],
+            return_type=cg.optional.template(cg.float_),
+        )
+        cg.add(var.set_target_temperature_lambda(template_))
+
     if CONF_MODE in config:
         template_ = await cg.process_lambda(
             config[CONF_MODE],

esphome/components/template/water_heater/template_water_heater.cpp

@@ -16,7 +16,8 @@ void TemplateWaterHeater::setup() {
       restore->perform();
     }
   }
-  if (!this->current_temperature_f_.has_value() && !this->mode_f_.has_value())
+  if (!this->current_temperature_f_.has_value() && !this->target_temperature_f_.has_value() &&
+      !this->mode_f_.has_value())
     this->disable_loop();
 }
 
@@ -28,6 +29,9 @@ water_heater::WaterHeaterTraits TemplateWaterHeater::traits() {
   }
 
   traits.set_supports_current_temperature(true);
+  if (this->target_temperature_f_.has_value()) {
+    traits.add_feature_flags(water_heater::WATER_HEATER_SUPPORTS_TARGET_TEMPERATURE);
+  }
   return traits;
 }
 
@@ -42,6 +46,14 @@ void TemplateWaterHeater::loop() {
     }
   }
 
+  auto target_temp = this->target_temperature_f_.call();
+  if (target_temp.has_value()) {
+    if (*target_temp != this->target_temperature_) {
+      this->target_temperature_ = *target_temp;
+      changed = true;
+    }
+  }
+
   auto new_mode = this->mode_f_.call();
   if (new_mode.has_value()) {
     if (*new_mode != this->mode_) {

esphome/components/template/water_heater/template_water_heater.h

@@ -20,6 +20,9 @@ class TemplateWaterHeater : public Component, public water_heater::WaterHeater {
   template<typename F> void set_current_temperature_lambda(F &&f) {
     this->current_temperature_f_.set(std::forward<F>(f));
   }
+  template<typename F> void set_target_temperature_lambda(F &&f) {
+    this->target_temperature_f_.set(std::forward<F>(f));
+  }
   template<typename F> void set_mode_lambda(F &&f) { this->mode_f_.set(std::forward<F>(f)); }
 
   void set_optimistic(bool optimistic) { this->optimistic_ = optimistic; }
@@ -44,6 +47,7 @@ class TemplateWaterHeater : public Component, public water_heater::WaterHeater {
   // Ordered to minimize padding on 32-bit: 4-byte members first, then smaller
   Trigger<> set_trigger_;
   TemplateLambda<float> current_temperature_f_;
+  TemplateLambda<float> target_temperature_f_;
   TemplateLambda<water_heater::WaterHeaterMode> mode_f_;
   TemplateWaterHeaterRestoreMode restore_mode_{WATER_HEATER_NO_RESTORE};
   water_heater::WaterHeaterModeMask supported_modes_;

tests/components/template/common-base.yaml

@@ -412,6 +412,7 @@ water_heater:
     name: "Template Water Heater"
     optimistic: true
     current_temperature: !lambda "return 42.0f;"
+    target_temperature: !lambda "return 60.0f;"
     mode: !lambda "return water_heater::WATER_HEATER_MODE_ECO;"
     supported_modes:
       - "OFF"

tests/integration/fixtures/water_heater_template.yaml

@@ -10,6 +10,7 @@ water_heater:
     name: Test Boiler
     optimistic: true
     current_temperature: !lambda "return 45.0f;"
+    target_temperature: !lambda "return 60.0f;"
     # Note: No mode lambda - we want optimistic mode changes to stick
     # A mode lambda would override mode changes in loop()
     supported_modes:

tests/integration/test_water_heater_template.py

@@ -85,6 +85,9 @@ async def test_water_heater_template(
         assert initial_state.current_temperature == 45.0, (
             f"Expected current temp 45.0, got {initial_state.current_temperature}"
         )
+        assert initial_state.target_temperature == 60.0, (
+            f"Expected target temp 60.0, got {initial_state.target_temperature}"
+        )
 
         # Test changing to GAS mode
         client.water_heater_command(test_water_heater.key, mode=WaterHeaterMode.GAS)