Check if CPF already exists with Jquery Validate

Question

I am validating some fields of an application form that was made in Ruby on Rails. In this application has some query endpoint, where it returns a json, if the CPF exists it returns this data:

{
  "existe": true,
  "user": {
  "name": "Operador 2",
  "cpf": "606.304.220-29"
  }
}

And if it doesn’t exist it returns

{  
   "existe":false
}

The URL to query the CPF is the following way: http://localhost:3000/api/findUserByCpf? Cpf=606.304.220-28

And the js code of Jquery Validation, he’s returning the message on the console, but doesn’t help the countryside, making the field valid or invalid.

$(".validationNomeOperador").validate({
rules: {
    'cpf': {
        required: true,
        cpf: true,
        remote: {
            url: "/api/findUserByCpf",
            type: "GET",
            data: {
                cpf: function() {
                    return $("#validationCpfOperador").val()
                }
            },
            dataType: 'json',
            success: function(data) {
                if (data.existe == true) {
                    console.log("Já existe o CPF cadastrado")
                } else {
                    console.log("CPF disponivel")
                }
            }
        }
    },
},
messages: {
    'cpf': {
        required: "Informe o CPF",
        remote: 'CPF já cadastrado'
    },
}
});

Answer 1

Usually this return is produced as an example?

json_encode(array('existe' => 'true'));

so that the code of jquery.validation understand in the validation configuration remote need to read this key as follows:

rules: {
    cpf: {
        required:true,
        remote: {
            url:'val.php',
            type:'post',
            dataType: 'json',
            dataFilter: function(d){
                response = JSON.parse(d);
                return !response.existe;
            } 
        }
    }
}

making this configuration, the code searches if the result was true or false which is what you need to validate or not the field.

Answer 2

From what I just read in the documentation, your parameter remote request need to handle only true or false to perform the validation and display the custom message you set in the Jquery Validate.

If my line of reasoning is correct, you should change your endpoint to return only boolean in sponse or change the validation message dynamically with Jquery itself.

Edit

But searching a little I think I found a solution for you; Change the parameter success for dataFilter:

dataFilter: function(data) {        
    return data.existe ? true : false;
}