how to show data in one pie chart from different splunk search result

[neha_h]

I have below splunk events / search result:-
message: host id :undefined, test Id :"42342424-8bf9-4abdc", msg : processing test data
message: host id :undefined, test Id :"4eee2ab1-8bf9-4abdc", msg : data processing for test
message: host id :undefined, test Id :"5eee2ab1-8bf9-43434", msg : data processing for test
message: host id :undefined, test Id :"4234244-3339-4abdc", msg : processing test data
message: host id :undefined, test Id :"4ujuj-8bf9-qwqweees", msg : data processing for test1
message: host id :undefined, test Id :"4tft-8bf9-hjhheeessss", msg : data processing for test1
extras-path: /v1/test-data/test-update

I want to show the data in pie chart, so it should show 3 slice in 1 pie chart basically based on the msg part
so 2 count for data processing for test and 2 count for data processing for test1 and 1 count for this path
Actually i am not sure how to evaluate msg key and how to display 3 different result in 1 pie-chat . plz anyone can help.

[to4kawa]

| makeresults 
| eval _raw="message: host id :undefined, test Id :\"4eee2ab1-8bf9-4abdc\", msg : data processing for test
message: host id :undefined, test Id :\"5eee2ab1-8bf9-43434\", msg : data processing for test
message: host id :undefined, test Id :\"4ujuj-8bf9-qwqweees\", msg : data processing for test1
message: host id :undefined, test Id :\"4tft-8bf9-hjhheeessss\", msg : data processing for test2" 
| multikv noheader=t 
| fields _raw 
| rename COMMENT as "from here, the logic" 
| rex "msg : (?<msg>.*)" 
| stats count by msg

1. extract msg field
2. aggregate by stats
3. display on Pie Chart

[neha_h]

@to4Kawa, but test Id is the random number generated unique everytime, I can't give any specific id in the search query. I just want to extract msg part which starts with "data processing"

[to4kawa]

use rex field=msg

[neha_h]

Not working , i have updated my question with more details, I tried this but no luck:
index="testing" application="test-data" | rex field=msg

[to4kawa]

see reference
https://docs.splunk.com/Documentation/Splunk/latest/SearchReference/Rex