JSON transfer to Codeigniter via AJAX

Question

I’m not able to pass a string in the format JSON for a controller of Codeigniter via AJAX.

A string JSON:

var avaliacao= {"avaliacao":[{"pergunta":"Qual sua idade?"}[{"resposta_certa":"99","resposta_err1":"11","resposta_err2":"15",
"resposta_err3":"14","resposta_err4":"27"}]]}

THE JS:

var controller = 'endereco/controller';
var base_url = 'dominio/do/site';

function grava_avaliacao(){ 

    jQuery.ajax({
        url : base_url + '/' + controller + '/add',
        type : 'POST', 
        data : avaliacao,
        dataType: 'json',
        success : function(data){ 
                        alert(data);
                    }
    });
}

The controller:

public function add(){
    var_dump(json_decode($this->input->post('avaliacao')));
}

Answer 1

Use JSON.stringify() to convert your object into a Json string in the attribute data of function ajax.

The parameter data accepts a string or an object, but it does not automatically convert to Json but to the format of query string. It’s a common confusion.

Example:

jQuery.ajax({
    url : base_url + '/' + controller + '/add',
    type : 'POST', 
    data : { 'avaliacao': JSON.stringify(avaliacao) },
    dataType: 'json',
    success : function(data){ 
                    alert(data);
                }
});

---

Update

According to the comments, there was also a problem in the URL, because the controller method was not even executed. So, one should always check whether the URL used in Ajax commands is correct, especially when using frameworks that abstract the path.