How to use REX in a search called via REST API?

[Stuartb_]

In my first post,

I need to search Splunk using the REST API. How do I get the system to actually return me some results?

Steps

1. POST a search, example: 

search=search index=myIndex earliest=-1d "[nice-keyword]" AND "Nice catch-phrase" | rex field=_raw "reportingSystem\":\s+\"(?<system>\d{3})[\s\S]+operationCode\":\s+\"(?<opcode>\w+)[\s\S]+ticketId\":\s+\"(?<ticket>\d*)[\s\S]+transactionCode\":\s+\"(?<txcode>\w+)[\s\S]+NumericCode\":\s+\"(?<agency>\d*)" | table system, opcode, txcode, agency​

• In the SEARCH User Interface, this makes a nice report
• Grab the job search ID.
• Continually GET the job status of the POSTed search until DONE or something else that helps me stop polling.
• Ask for the job results. Get 200 OK but no content.

How does one actually format a search that can provide actual results via the API?

Stumped. For days. I'm using Postman before moving on to my favorite middleware tool.

Thank you.

[Stuartb_]

Having found that url encoding works well (thanks to other posters), I have made some progress! Next to work out how to find the eventId and to be able to do a JOIN in the same search via API.