You want some auto-conversion from row -> JSON structure?! 

However think on how your POST/PUSH works expect to receive:

{ "id" : 0 , "name" : "foo" , "age" : 24 }

Or

{ "target" : "person" , 
"update" : [
      { "id" : 0 , "name" : "foo" , "age" : 24 },
      { "id" : 35, "name" : "foometwice" , "age" : 65 }
    ]
}

Or ..... so many different ways 

"Auto conversion" is possible with tJSONWriteField ... you can do some automapping isnt there a checkbox ,  but you probably need to adjust this output to fit your push/post, but it ends up in an array like the first example. There;s no magic component to do it for you beside writing some Java code and tJavaRow / tJavaFlex ... 

However to read/write dynamic schema in Open Studio... take a closer look on this thread : https://community.talend.com/t5/Design-and-Development/Dynamic-schema-alternative-in-Open-Studio/m-p...

Keep it clean, sometimes it helps being clear on what you're trying to do!