Odata Service with the following format

Hello Experts,

Can I create an Odata service which will return me the following json format, without using association and navigation?

If yes, request you to please suggest how could I achieve that.

{   "category" : [      {  "dkey" : "01",   "dtext" : "Zero One"  ,    "subCategory":[{      "dkey":"A",      "dtext":"Alfa A"    }]
},
{   "dkey" : "02",   "dtext" : "Zero Two"  ,    "subCategory":[{      "dkey":"B",      "dtext":"Beta B"    },{      "dkey":"G",      "dtext":"Gama G"    },{      "dkey":"D",      "dtext":"Delta D"    }]
}
]
}

Warm regards,

Upendra