Data persistance problems

Agent Code
1

I defined some variables :
Setting <- {}; Setting.TsKey <- "Unknown"; Setting.TsRefreshDelay <- 120; Setting.SiteName <- "Unknown"; Setting.SiteDescription <- "Unknown"; Setting.SiteAdress <- "Unknown"; Setting.SiteContactInfo <- "Unknown"; Setting.EmailRecipient <- "Unknown"; Setting.OtherDetails <- "";

and in the code, I have :
local table = server.load(); if (table.len() != 0) { Setting = table; } imp.wakeup(1,Main);

But whenever i’m trying to use the variable Setting.SiteName I got an error that say " ERROR: the index ‘SiteName’ does not exist"

I really dont get it

2

Did you add ‘SiteName’ to the table after doing a server.save()? if so the table loaded in the second block of code above will not include it. Where do you do your initial server.save() (to persist the data?) I would do something like:

`local table = server.load();
if (table.len() != 0) {
    // Table loaded; assign to Setting
    Setting = table;
} else {
    // No table loaded, ie. first run, so save the defaults
    server.save(Setting);
}

imp.wakeup(1,Main); `

FWIW, in my code I have a flag which I set to true every time I want the code to overwrite an existing persisted table, allowing me to add in new keys without error.

3

Ok, but why does this dont even work? :
`// Establish the device settings table with default values
clockPrefs <- {};
clockPrefs.mode <- true;
clockPrefs.bst <- false;
clockPrefs.utc <- false;
clockPrefs.offset <- 12;
clockPrefs.brightness <- 15;

// Load the settings table in from permanent storage
local settings = server.load();

// If no preferences have been saved, settings will be empty
if (settings.len() != 0) {
// Settings table is NOT empty so set the clockPrefs to the loaded table
clockPrefs = settings;
}

function Main(){

server.log("Brightness" + clockPrefs.brightness);
imp.wakeup(1,Main);

}

Main();`

I mean, its the exact code from here : https://electricimp.com/docs/api/server/load/

4

What do you mean by ‘it doesn’t work’? You should see ‘Brightness15’ in the log. The code above doesn’t do anything else. If you’re expecting to see a different value, you won’t because you don’t ever call server.save(clockPrefs) to write your settings to permanent storage (at least not in the code above).

5

Got it,
server.save(clockPrefs) need to run once…always

6

More specifically server.save needs to be called any time you change data in your table.

You may want to look at this code snippet:

It’s not well documented, but here is some completely untested code from memory which might do what you want:
`
//Set Defaults (Note: Second parameter of read is default value if they’ve never been set)
Persist.read(“mode”, true);
Persist.read(“bst”, false);
Persist.read(“utc”, false);
Persist.read(“offset”, 12);
Persist.read("brightness, 15);

//Called from code not shown here
function changeBrightness(value){
Persist.write(“brightness”, value);
}

function Main(){
server.log(“Brightness” + Persist.read(“brightness”);
imp.wakeup(1,Main);
}
Main();
`