使用 WifiManager 和 Arduinojson 6 保存自定义参数

如何解决使用 WifiManager 和 Arduinojson 6 保存自定义参数

我正在尝试将一个额外的自定义参数保存到 wifimanager，这是 mqtt 服务器地址，但库中和互联网上的所有代码都适用于 Arduinojson 5，我尝试尽我所能升级到 Arduinojson 6。代码运行没有问题，但是，当我重新启动 esp 时，它消失了。由于某种原因，它没有保存。

#include <FS.h>                   //this needs to be first,or it all crashes and burns...
#include <ESP8266WiFi.h>          //https://github.com/esp8266/Arduino
#include <DNSServer.h>
#include <ESP8266WebServer.h>
#include <WiFiManager.h>          //https://github.com/tzapu/WiFiManager
#include <ArduinoJson.h>          //https://github.com/bblanchon/ArduinoJson
#define TRIGGER_PIN 16

char mqtt_server[40];
bool shouldSaveConfig = false;
void saveConfigCallback () {  Serial.println("Should save config");  shouldSaveConfig = true; }

WiFiManager wifiManager;
WiFiManagerParameter custom_mqtt_server("server","mqtt server",mqtt_server,40);

void setup() {  
  Serial.begin(115200);     
  Serial.println("\n Starting");    
  pinMode(TRIGGER_PIN,INPUT);     

//clean FS,for testing
  //SPIFFS.format();

  if (SPIFFS.begin()) {
    Serial.println("** Mounting file system **");
    if (SPIFFS.exists("/config.json")) {
      //file exists,reading and loading
      Serial.println("** Reading config file **");
      File configFile = SPIFFS.open("/config.json","r");
      if (configFile) {
        size_t size = configFile.size();
        // Allocate a buffer to store contents of the file.
        std::unique_ptr<char[]> buf(new char[size]);

        configFile.readBytes(buf.get(),size);
        DynamicJsonDocument doc(1024);
        DeserializationError error = deserializeJson(doc,buf.get());
       
        // Test if parsing succeeds.
        if (error) {
          Serial.print(F("deserializeJson() Failed: "));
          Serial.println(error.c_str());
          return;
        }

        strcpy(mqtt_server,doc["mqtt_server"]);     //get the mqtt_server <== you need one of these for each param

      } else {
        Serial.println("** Failed to load json config **");
      }
      configFile.close();
      Serial.println("** Closed file **");
    }
  }
  else {
    Serial.println("** Failed to mount FS **");
  }
  wifiManager.setSaveConfigCallback(saveConfigCallback);
  wifiManager.addParameter(&custom_mqtt_server);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
    resetbtn();
  }
  
  Serial.println("connected...yeey :)");

  //read updated parameters
  strcpy(mqtt_server,custom_mqtt_server.getValue());

  //save the custom parameters to FS
  if (shouldSaveConfig) {
  Serial.println("saving config");
    DynamicJsonDocument doc(1024);
    doc["mqtt_server"] = mqtt_server;

    File configFile = SPIFFS.open("/config.json","w");
    if (!configFile) {
      Serial.println("Failed to open config file for writing");
    }

    serializeJson(doc,Serial);
    serializeJson(doc,configFile);    
    configFile.close();
    //end save
  }
}

void loop() {
  resetbtn();
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
    resetbtn();
  }
  Serial.println("Connected");
  wifiManager.process();
  saveParamsCallback();
  delay(3000);
}

void resetbtn() { if ( digitalRead(TRIGGER_PIN) == HIGH ) {    wifiManager.startConfigPortal("Horray");    Serial.println("connected...yeey :)");  } }
void saveParamsCallback () {
  Serial.println("Get Params:");
  Serial.print(custom_mqtt_server.getID());
  Serial.print(" : ");
  Serial.println(custom_mqtt_server.getValue());
}

解决方法

出于同样的目的而不是使用：serializeJson(doc,configFile); 我正在使用这个功能，对我来说效果很好

// for writing 

bool writeFile(const char * path,const char * message,unsigned int len){

    File file = SPIFFS.open(path,FILE_WRITE);

    if(!file){
        return false;
    }

    if(!file.write((const uint8_t *)message,len)){
        return false;
    }

    return true;
}

为了阅读，我正在使用这个功能

// for reading

int readFile(const char * path,char ** text){
    // retval int - number of characters in the file
    // in case of empty file 0
    // in case of directory or not found -1

    File file = SPIFFS.open(path);
    if(!file || file.isDirectory()){
        return -1;
    }

    int file_lenght = file.size();
    *text = (char*) malloc(file_lenght*sizeof(char));

    for(int i = 0; i < file_lenght; i++){
        
        (*text)[i] = file.read();

    }

    return file_lenght;
}

你可以这样使用这个函数：

#define WIFI_credential_filename "/config.json"

char * wifi_credentials;
int file_len = readFile(WIFI_credential_filename,&wifi_credentials);

// at this point "wifi_credentials" is filled with the content of 
   "/config.json" file

这是我的实现，当然可以改进，但我已经测试过它并且有效