99 lines
2.8 KiB
C++
99 lines
2.8 KiB
C++
#ifndef SettingsPersistence_h
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#define SettingsPersistence_h
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#include <ESPAsyncWebServer.h>
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#include <FS.h>
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#include <ArduinoJson.h>
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#include <AsyncJsonWebHandler.h>
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#include <AsyncJson.h>
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/**
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* At the moment, not expecting settings service to have to deal with large JSON
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* files this could be made configurable fairly simply, it's exposed on
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* AsyncJsonWebHandler with a setter.
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*/
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#define MAX_SETTINGS_SIZE 1024
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/*
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* Mixin for classes which need to save settings to/from a file on the the file system as JSON.
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*/
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class SettingsPersistence {
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protected:
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// will store and retrieve config from the file system
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FS* _fs;
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// the file path our settings will be saved to
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char const* _filePath;
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bool writeToFS() {
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// create and populate a new json object
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DynamicJsonDocument jsonDocument = DynamicJsonDocument(MAX_SETTINGS_SIZE);
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JsonObject root = jsonDocument.to<JsonObject>();
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writeToJsonObject(root);
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// serialize it to filesystem
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File configFile = _fs->open(_filePath, "w");
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// failed to open file, return false
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if (!configFile) {
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return false;
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}
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serializeJson(jsonDocument, configFile);
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configFile.close();
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return true;
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}
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void readFromFS() {
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File configFile = _fs->open(_filePath, "r");
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// use defaults if no config found
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if (configFile) {
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// Protect against bad data uploaded to file system
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// We never expect the config file to get very large, so cap it.
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size_t size = configFile.size();
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if (size <= MAX_SETTINGS_SIZE) {
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DynamicJsonDocument jsonDocument = DynamicJsonDocument(MAX_SETTINGS_SIZE);
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DeserializationError error = deserializeJson(jsonDocument, configFile);
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if (error == DeserializationError::Ok && jsonDocument.is<JsonObject>()){
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JsonObject root = jsonDocument.as<JsonObject>();
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readFromJsonObject(root);
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configFile.close();
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return;
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}
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}
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configFile.close();
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}
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// If we reach here we have not been successful in loading the config,
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// hard-coded emergency defaults are now applied.
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applyDefaultConfig();
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}
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// serialization routene, from local config to JsonObject
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virtual void readFromJsonObject(JsonObject& root){}
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virtual void writeToJsonObject(JsonObject& root){}
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// We assume the readFromJsonObject supplies sensible defaults if an empty object
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// is supplied, this virtual function allows that to be changed.
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virtual void applyDefaultConfig(){
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DynamicJsonDocument jsonDocument = DynamicJsonDocument(MAX_SETTINGS_SIZE);
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JsonObject root = jsonDocument.to<JsonObject>();
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readFromJsonObject(root);
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}
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public:
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SettingsPersistence(FS* fs, char const* filePath):
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_fs(fs), _filePath(filePath) {}
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virtual ~SettingsPersistence() {}
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};
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#endif // end SettingsPersistence
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