I want to convert a model query to json with json_encode, it doesn't work. But with a ordinary array it does.

 $arr = array("one", "two", "three");
       $data["json"] = json_encode($arr);

Output

 
 var arr=["one","two","three"];

But when I try to convert a query codeigniter throws an error. What is it with that? This is the error message:

A PHP Error was encountered Severity: Warning Message: [json] (php_json_encode) type is unsupported, encoded as null

And the converted "query" result = I mean model method is like this:

{"conn_id":null,"result_id":null,"result_array":[],"result_object":[],"current_row":0,"num_rows":9,"row_data":null} 

I try to do like this

 $posts = $this->Posts_model->SelectAll();
       $data["posts"] = json_encode($posts); 

By the way, the model and method works just fine when I do it without json_encode.

Something I'm propably doing wrong, but the question is what?