[nextion] Publishes is_connected() (#7961)

esphome/components/nextion/nextion.cpp

@@ -40,7 +40,7 @@ bool Nextion::send_command_(const std::string &command) {
 }
 
 bool Nextion::check_connect_() {
-  if (this->get_is_connected_())
+  if (this->is_connected_)
     return true;
 
   // Check if the handshake should be skipped for the Nextion connection

esphome/components/nextion/nextion.h

@@ -1217,6 +1217,25 @@ class Nextion : public NextionBase, public PollingComponent, public uart::UARTDe
    */
   bool is_updating() override;
 
+  /**
+   * @brief Check if the Nextion display is successfully connected.
+   *
+   * This method returns whether a successful connection has been established with
+   * the Nextion display. A connection is considered established when:
+   *
+   * - The initial handshake with the display is completed successfully, or
+   * - The handshake is skipped via skip_connection_handshake_ flag
+   *
+   * The connection status is particularly useful when:
+   * - Troubleshooting communication issues
+   * - Ensuring the display is ready before sending commands
+   * - Implementing connection-dependent behaviors
+   *
+   * @return true if the Nextion display is connected and ready to receive commands
+   * @return false if the display is not yet connected or connection was lost
+   */
+  bool is_connected() { return this->is_connected_; }
+
  protected:
   std::deque<NextionQueue *> nextion_queue_;
   std::deque<NextionQueue *> waveform_queue_;
@@ -1315,8 +1334,6 @@ class Nextion : public NextionBase, public PollingComponent, public uart::UARTDe
 
 #endif  // USE_NEXTION_TFT_UPLOAD
 
-  bool get_is_connected_() { return this->is_connected_; }
-
   bool check_connect_();
 
   std::vector<NextionComponentBase *> touch_;

tests/components/nextion/common.yaml

@@ -1,5 +1,7 @@
 esphome:
   on_boot:
+    - lambda: 'ESP_LOGD("display","is_connected(): %s", YESNO(id(main_lcd).is_connected()));'
+
     # Binary sensor publish action tests
     - binary_sensor.nextion.publish:
         id: r0_sensor