Creating Your Own Data Files

The purpose of DataFileBase is to act as a base when defining your own data objects that you would like to be saved and retrieved from disk.

Here are some key points when defining your own configuration objects:

• Your data object's constructor must take const std::string& key and const std::string& appName parameters and pass it to DataFileBase's constructor.
  • Although you will not use key and appName in your own implementation, it is required for DataFileBase's functionality and will be filled-in by the DataFileManager.
• DataFileBase exposes a protected m_json object which you must use in your implementation of getting and storing variables of your data object.
  • If this m_json object is not used, your data object will not be stored to disk correctly.
• You must explicitly call the save method on your configuration object when you want to save the configuration to disk. Writing to the m_json (of type boost::json::object) object is not enough to trigger saving the file on disk.

Here is an example of a custom configuration object using DataFileBase:

using namespace Nickvision::App;
using namespace Nickvision::Events;
 
class AppConfig : public DataFileBase
{
public:
    AppConfig(const std::string& key, const std::string& appName)
        : DataFileBase{ key, appName } 
    { 
 
    }
 
    bool getAutomaticallyCheckForUpdates() const
    {
        const boost::json::value& value{ m_json["AutomaticallyCheckForUpdates"] };
        if(!value.is_bool())
        {
            return true;
        }
        return value.as_bool();
    }
 
    void setAutomaticallyCheckForUpdates(bool value)
    {
        m_json["AutomaticallyCheckForUpdates"] = value;
    }
};
 
//This object can now be used with the DataFileManager:
 
int main()
{
    DataFileManager dfm{ "AppName" };
    AppConfig& config{ dfm.get<AppConfig>("config") };
    config.saved() += [](const EventArgs& e) { std::cout << "Config saved to disk." << std::endl; };
    if(config.getPreviousCount() > 0)
    {
        std::cout << config.getPreviousCount() << std::endl;
    }
    config.setPreviousCount(6);
    config.save(); //above lambda will be invoked on success
    return 0;
}