Robot's Tracker Application

[SancheZZY]

Hey guys, I am currently studing for master in electronics and computer engineering, and I'm currently developing an application, for "software engineering" course.

Application: The purposed application has an tcp server able to handle several connections with the robots.
I choosed to work with database/ no files, so i'm using a sqlite db to save information about the robots and their full history, models of robots, tasks, etc...
The robots send us several data like odometry, tasks information, and so on...

I create a thread for every new robot's connection to handle the messages and update the informations of the robots on the database. Now lets start talk about my problems:

The application got to show information about the robots in realtime, and I was thinking about using QSqlQueryModel, set the right query and the show it on a QTableView but then I got to some problems/ solutions to think about:


Problem number 1: There are informations to show on the QTableView that are not on the database: I have the current consumption on the database and the actual charge on the database in capacity, but I want to show also on my table the remaining battery time, how can I add that column with the right behaviour (math implemented) in my TableView.


Problem number 2: I will be receiving messages each second for each robot, so, updating the db and the the gui(loading the query) may not be the best solution when I have a big number of robots connected? Is it better to update the table, and only update the db each minute or something like this? If I use this method I cant work with the table with the QSqlQueryModel to update the tables, so what is the approach that you recommend me to use?

Thanks
SancheZ

[d_stranz]

Problem number 1: There are informations to show on the QTableView that are not on the database: I have the current consumption on the database and the actual charge on the database in capacity, but I want to show also on my table the remaining battery time, how can I add that column with the right behaviour (math implemented) in my TableView.

One solution is to derive a custom model from QSqlQueryModel and re-implement the columnCount() and data() methods. The first method should return the number of actual columns plus the number of computed columns. In the second method, if the column referenced in the QModelIndex parameter is less than the query column count, then you simply call QSqlQueryModel::data() with the same arguments as you were passed. If the column number refers to a computed column -and- the role is Qt::DisplayRole, then you compute your value, format it into a QString, and return that. For other roles, you return QVariant().

Problem number 2: I will be receiving messages each second for each robot, so, updating the db and the the gui(loading the query) may not be the best solution when I have a big number of robots connected? Is it better to update the table, and only update the db each minute or something like this? If I use this method I cant work with the table with the QSqlQueryModel to update the tables, so what is the approach that you recommend me to use?

No suggestion here. It depends on the size of the database, how much of it is displayed, and how frequently the database and screen are updated.

You could consider a temporary database that accumulates the real-time data as it comes in, then periodically transfers that to the "real" database; this would make your UI a little jerky maybe, but then it wouldn't slow to a crawl with constant updates. Or you could derive a custom QTableView that has connections to the query model's modelReset() and other signals that denote a change in the data. The slots that handle these signals could start / restart a QTimer and/or keep count of the number of calls. When the timer times out or the maximum number of calls is reached, then the view is allowed to update. Reset the counter and wait again.