Problem with conversion (logstash & kibana)

Hello everybody ,
I try to convert a field "tmp_reponse" in integer in the file "conf" with logstash as follows
mutate {
convert => {"TMP_REPONSE" => "integer"}

,but on Kibana it shows me that he is still string. I do not understand how I can make a convertion to use my fields "tmp_response" to use it like as a metric fields on kibana

thank you help me please and if there is anyone who can explain to me how I can master the metrics on Kibana and use fields as being of metrics fields

In the actual Elasticsearch mapping, is it mapped as a string or an integer? If it is mapped as an integer, have you tried refreshing your field mappings in Kibana?