Hello,
I started writing a CRON event based rule to handle my dynamic DNS change at home. Basically, few simple steps
Get current external IP
Check previous IP value to see if changes occured
If any, call API with sendHttpPostRequest to update new IP on DDNS provider.
I’m stuck on step 2 : how can I store variable value on rule execution N and retrieve it on execution N+1 to compare both? I saw things to store Item values, but I wonder if I can do the same with variables.
Is there some reason you can’t have an Item (string perhaps) and update your value to it? It’s just there then, no further action needed.
If you persist that Item, it will survive across OH reboots too.
No reason at all, but the fact I’m a beginner and didn’t even notice there was a text Item.
Thank you for your suggestion, I’m sure that will do!
I let you know.
Code if any other beginners interested (in dynamicDNS.rules) :
/* Check IP using external service */
rule "Dynamic DNS check"
when
Time cron "0 0/3 * 1/1 * ? *"
then
// Initiates variables
var String checkIpUrl = "http://ipecho.net/plain"
// Get current external IP
var ip = sendHttpGetRequest(checkIpUrl)
// compare last IP and new
if(wanIpAddress.state.toString != ip) {
logInfo("ddns.status", "WAN IP changed : " + wanIpAddress.state.toString + " (previous) to " + ip + " (new)")
postUpdate(wanIpAddress, ip)
}
end
/* Update DDNS IP entry to API */
rule "Dynamic DNS update"
when
Item wanIpAddress received update
then
var String hostname = "hostname"
var String username = "username"
var String password = "pass"
// Update IP
var apiReturn = sendHttpGetRequest("https://api.dynu.com/nic/update?hostname=" + hostname + "&myip=" + wanIpAddress.state.toString + "&username=" + username + "&password=" + password)
logInfo("ddns.update", "API return : " + apiReturn)
end
