[nextion] Pass std::string to custom-protocol automations that defer (#20571)

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

esphome/components/nextion/display.py

@@ -11,6 +11,7 @@ from esphome.const import (
     PLATFORM_ESP8266,
 )
 from esphome.core import CORE, TimePeriod
+from esphome.types import ConfigType, TemplateArgsType
 
 from . import FILTER_SOURCE_FILES, Nextion, nextion_ns, nextion_ref  # noqa: F401  pylint: disable=unused-import
 from .base_component import (
@@ -177,6 +178,10 @@ _CALLBACK_AUTOMATIONS = (
     automation.CallbackAutomation(
         CONF_ON_BUFFER_OVERFLOW, "add_buffer_overflow_event_callback"
     ),
+)
+
+# The strings live only while the callback runs
+_CUSTOM_CALLBACK_AUTOMATIONS = (
     automation.CallbackAutomation(
         CONF_ON_CUSTOM_BINARY_SENSOR,
         "add_custom_binary_sensor_callback",
@@ -293,3 +298,18 @@ async def to_code(config):
             cg.add_define(define_name)
 
     await automation.build_callback_automations(var, config, _CALLBACK_AUTOMATIONS)
+    for entry in _CUSTOM_CALLBACK_AUTOMATIONS:
+        for conf in config.get(entry.conf_key, []):
+            await automation.build_callback_automation(
+                var, entry.callback_method, _owning_args(entry.args, conf), conf
+            )
+
+
+def _owning_args(args: TemplateArgsType, conf: ConfigType) -> TemplateArgsType:
+    """Pass std::string instead of StringRef to an automation that defers, as it keeps its arguments."""
+    if not automation.has_non_synchronous_actions(conf):
+        return args
+    return [
+        (cg.std_string if type_ is cg.StringRef else type_, name)
+        for type_, name in args
+    ]

tests/component_tests/nextion/config/custom_triggers.yaml

@@ -0,0 +1,21 @@
+esphome:
+  name: test
+
+esp32:
+  board: esp32dev
+  framework:
+    type: esp-idf
+
+uart:
+  tx_pin: 17
+  rx_pin: 16
+  baud_rate: 115200
+
+display:
+  - platform: nextion
+    on_custom_text_sensor:
+      - then:
+          - lambda: 'ESP_LOGD("test", "%s=%s", key.c_str(), value.c_str());'
+      - then:
+          - delay: 1s
+          - lambda: 'ESP_LOGD("test", "%s=%s", key.c_str(), value.c_str());'

tests/component_tests/nextion/test_custom_trigger_args.py

@@ -0,0 +1,47 @@
+"""Tests for the argument types of the nextion custom-protocol triggers."""
+
+from collections.abc import Callable
+from pathlib import Path
+
+import esphome.codegen as cg
+from esphome.components.nextion.display import _owning_args
+from esphome.core import Lambda
+
+ARGS = [(cg.StringRef, "key"), (cg.bool_, "value")]
+SYNCHRONOUS_ACTION = {"lambda": Lambda('ESP_LOGD("test", "ran");')}
+DEFERRING_ACTION = {"delay": "1s"}
+TRUE_CONDITION = {"lambda": Lambda("return true;")}
+
+
+def test_synchronous_automation_keeps_string_ref() -> None:
+    assert _owning_args(ARGS, {"then": [SYNCHRONOUS_ACTION]}) == ARGS
+
+
+def test_deferring_automation_gets_std_string() -> None:
+    assert _owning_args(ARGS, {"then": [SYNCHRONOUS_ACTION, DEFERRING_ACTION]}) == [
+        (cg.std_string, "key"),
+        (cg.bool_, "value"),
+    ]
+
+
+def test_nested_deferring_action_gets_std_string() -> None:
+    actions = [{"if": {"condition": TRUE_CONDITION, "then": [DEFERRING_ACTION]}}]
+    assert _owning_args(ARGS, {"then": actions})[0] == (cg.std_string, "key")
+
+
+def test_all_string_refs_swapped() -> None:
+    args = [(cg.StringRef, "key"), (cg.StringRef, "value")]
+    assert _owning_args(args, {"then": [DEFERRING_ACTION]}) == [
+        (cg.std_string, "key"),
+        (cg.std_string, "value"),
+    ]
+
+
+def test_generated_automation_types(
+    generate_main: Callable[[str | Path], str],
+    component_config_path: Callable[[str], Path],
+) -> None:
+    main_cpp = generate_main(component_config_path("custom_triggers.yaml"))
+
+    assert "Automation<StringRef, StringRef>" in main_cpp
+    assert "Automation<std::string, std::string>" in main_cpp

tests/components/nextion/common.yaml

@@ -287,13 +287,20 @@ display:
       then:
         logger.log: "Nextion reported a buffer overflow!"
     on_custom_text_sensor:
-      then:
-        - lambda: |-
-            // key: StringRef, value: StringRef
-            if (key == "csv") {
-              // parse value here, or forward to your own component
-              ESP_LOGD("nextion.csv", "Got CSV: %s", value.c_str());
-            }
+      - then:
+          - lambda: |-
+              // key: StringRef, value: StringRef
+              if (key == "csv") {
+                // parse value here, or forward to your own component
+                ESP_LOGD("nextion.csv", "Got CSV: %s", value.c_str());
+              }
+      # Deferring: key and value are passed as std::string
+      - then:
+          - delay: 1s
+          - lambda: |-
+              if (key == "csv") {
+                ESP_LOGD("nextion.csv", "Got CSV earlier: %s", value.c_str());
+              }
     on_custom_sensor:
       then:
         - lambda: |-
@@ -308,9 +315,13 @@ display:
               ESP_LOGD("nextion.btn", "btn1=%s", ONOFF(value));
             }
     on_custom_switch:
-      then:
-        - lambda: |-
-            ESP_LOGD("nextion.sw", "%s=%s", key.c_str(), ONOFF(value));
+      - then:
+          - lambda: |-
+              ESP_LOGD("nextion.sw", "%s=%s", key.c_str(), ONOFF(value));
+      - then:
+          - delay: 1s
+          - lambda: |-
+              ESP_LOGD("nextion.sw", "%s was %s", key.c_str(), ONOFF(value));
     on_page:
       then:
         lambda: 'ESP_LOGD("display","Display shows new page %u", x);'