I have something set up in Node Red to do the same thing, although I haven't had cause to watch for any tags yet. I don't use Home Assistant - I'm using Hubitat for home automation - but I think standing up Node Red is probably quicker and easier than Home Assistant, so it might be a good option unless you want Home Assistant for other things.
I send LPR alert information to MQTT so that I can log the tags in a database via Node Red. I have a separate flow in Node Red that uses a function node to check the tags. Unless you have really easy-to-read tags in your locale and a really good view of each tag, you probably want to account for partial matches as well as exact matches. If it's important enough to have real-time alerts set up, then it's probably important enough to be notified when a tag is read that is very similar to the one you are watching for.
I'll 'spoiler' the rest of the details to avoid cluttering up the thread:
My flow is fairly simple.. MQTT -> Function to compare the read to a list of tags -> Switch for whether the hit was exact or partial -> Change node to set up my notification -> Send to my notification server
My function is below. This is still a work in progress and it could be made better with a little effort.
The MQTT message is JSON format and the tag that was detected is in msg.payload.plate. On the 4th line of my function I list the tags I want to watch for, including all the partial cases I think might result from misreading. So for ABC1234 I might enter the full tag, but also BC123, C1234, ABC123, etc. The more partial tags, the more false hits I'll get, but the less change of missing a hit.
The result of the function is I get either a message saying there was an exact match, or a message saying what plate was read and what it matched from the list.
If I'm watching for ABC1234 and the LPR reads 8C1234 (missing the first character, mis-reading the B), it would generate a msg.notfiy_text of: "Partial matches: Tag 8C1234 matched C1234"
If I get time to try to enhance this, I think it would be useful to be able to list the full tag I'm looking for, a text description/reason, and the partial elements for just that tag, so the message could be something like:
"Tag 8C1234 is a partial match for ABC1234 - Blue Honda Accord - car break-ins"
Looks like I'm going to have to dig a bit deeper into multi-dimensional arrays.
My function is below. This is still a work in progress and it could be made better with a little effort.
The MQTT message is JSON format and the tag that was detected is in msg.payload.plate. On the 4th line of my function I list the tags I want to watch for, including all the partial cases I think might result from misreading. So for ABC1234 I might enter the full tag, but also BC123, C1234, ABC123, etc. The more partial tags, the more false hits I'll get, but the less change of missing a hit.
Code:
var tag = msg.payload.plate
/tags to watch for
var check_for = ['ABC1234', 'BC123', 'C1234', 'ABC123']
const partial = check_for.filter(el => tag.includes(el))
/exact match
if ( check_for.includes(tag) )
{
msg.notify_text = 'Exact Match - ' + tag + " "
msg.hit_type = 'exact'
return msg;
}
else if ( partial.length > 0 )
{
/partial match
msg.notify_text = "Partial matches: Tag " + tag + " matched " + partial
msg.hit_type = 'partial'
return msg;
}
else
{
/no match
return null;
}The result of the function is I get either a message saying there was an exact match, or a message saying what plate was read and what it matched from the list.
If I'm watching for ABC1234 and the LPR reads 8C1234 (missing the first character, mis-reading the B), it would generate a msg.notfiy_text of: "Partial matches: Tag 8C1234 matched C1234"
If I get time to try to enhance this, I think it would be useful to be able to list the full tag I'm looking for, a text description/reason, and the partial elements for just that tag, so the message could be something like:
"Tag 8C1234 is a partial match for ABC1234 - Blue Honda Accord - car break-ins"
Looks like I'm going to have to dig a bit deeper into multi-dimensional arrays.
Edit: enhanced version is down-thread - Blue Iris and CodeProject.AI ALPR
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