Testing for custom data

Hello again! I've been looking for a way to execute if data and test for a certain string in the json object. I've learned that you can do this if your target is in an array by doing execute if data storage x abc.[{type:"a"}]. But what if the data is just structured like {abc:{type:"a"}} instead of {abc:[{type:"a"}]}?
I can't seem to figure this out on my own so any help is appreciated.