Serialize objects

[cuyogomez]

Hi people. i have a problem... I have a Brand Object with name and id attributes. Then i have a Car with name, color, and foreign key to Brand Object. I need to return a JSON response with a list of Brands and foreach brand display all the cars, but when i do that, my response is
[
{
id:"1",
name:"Ford",
cars:
[
{Car object},
{Car object}
]
}
]

So, the Car object isn't serialized... how can i do that??? Please is urgent!!