Regex to match the last value in given data - arrays

Question

I get data from a URL, and am working on the data to check for a few conditions. The data from the URL look like this:
1528190345":100,"1528190346":100,"1528190368":100,"1528190414":100,"1528190439":99,"1528190440":99,"1528190463":100,"1528190485":100,"1528190508":100,"1528190550":100,"1528190575":100,"1528190576":100,"1528190599":100,"1528190600":100,"1528190622":100,"1528190667":100,"1528190688":100,"1528190689":100,"1528190712":100,"1528190736":100,"1528190762":100,"1528190785":100,"1528190786":100,"1528190807":100,"1528190828":100,"1528190853":100,"1528190877":100,"1528190901":100,"1528190925":100,"1528190948":100,"1528190968":100,"1528190991":100}}]
====
I have converted that too JSON
{"metric"=>"Insta_real-unique_value", "tags"=>{"host"=>"letme.quickly.com", "tier"=>"2", "device"=>"tester1", "dc"=>"xxx"}, "aggregateTags"=>["device_name", "device_ip"], "dps"=>{"1526972408"=>100, "1526972424"=>100, "1526972440"=>100, "1526972456"=>100, "1526972472"=>100, "1526972488"=>100, "1526972504"=>100, "1526972520"=>100, "1526972536"=>100, "1526972552"=>100, "1526972568"=>100, "1526972569"=>100, "1526972584"=>100, "1526972585"=>100, "1526972601"=>100, "1526972617"=>100, "1526972633"=>100, "1526972649"=>100, "1526972665"=>100, "1526972681"=>100}}
I want to extract the value that corresponds to 100. When I do this:
url = "#{URL}"
uri = URI(url)
response = Net::HTTP.get(uri)
value = response[-6..-4]
puts value
I get the last value, but when the last value changes to 99/9/0, it prints :99 or ":9.
Is there a way to get the exact value as is?

Answer 1

When dealing with JSON data, it's almost always better to parse the data properly rather than using regex against the string.
In this case, we can do:
JSON.parse(response)['dps'].values.last #=> 100

Answer 2

If the response is a json response, you must use a json parser else if is not a json response, you can use a regex expression with a Regex Object.
In case of a json response, assuming that the object is something like is declared into the variable response of the next code, you can parse it into a JObject. (using Newtonsoft.Json available from nuget repository).
See the next example :
string response = "[{\"response\":{\"1528190345\":100,\"1528190346\":100,\"1528190368\":100,\"1528190414\":100,\"1528190439\":99,\"1528190440\":99,\"1528190463\":100,\"1528190485\":100,\"1528190508\":100,\"1528190550\":100,\"1528190575\":100,\"1528190576\":100,\"1528190599\":100,\"1528190600\":100,\"1528190622\":100,\"1528190667\":100,\"1528190688\":100,\"1528190689\":100,\"1528190712\":100,\"1528190736\":100,\"1528190762\":100,\"1528190785\":100,\"1528190786\":100,\"1528190807\":100,\"1528190828\":100,\"1528190853\":100,\"1528190877\":100,\"1528190901\":100,\"1528190925\":100,\"1528190948\":100,\"1528190968\":100,\"1528190991\":100}}]";
List<Dictionary<string, Dictionary<string, int>>> values = JsonConvert.DeserializeObject<List<Dictionary<string, Dictionary<string, int>>>>(response);
Dictionary<string, Dictionary<string, int>> firstLevel = values[0]; // Access to the first object of the list closed with ']'
Dictionary<string, int> secondLevel = firstLevel["response"]; // Access to the first object response and get's it's object context of first '}' starting from the end of response
/** This is an option, if you ever knows the name of the element (1528190991) */
int thirdLevel = secondLevel["1528190991"]; // Access to the last element of the object by it's name, context of second '}' starting from the end of response.
Console.WriteLine(thirdLevel);
/** This is another option if you doesn't know the name of the element and wants ever the last element. */
List<int> listOfValues = secondLevel.Values.ToList();
Console.WriteLine(listOfValues[listOfValues.Count-1]);
Note that i've chenged a little bit your response adding [{\"response\":{\" at the start to become a json response.
If is not a json response you can use this pattern with regular expression :
:(.{2,6})}}\]$
Hope will help!