Handle error: "Uncaught Typeerror: Cannot read Property of 'value' Undefined"

Question

Hello,

When making an AJAX request, I have the following error:

Uncaught TypeError: Cannot read property of 'rede' undefined.

Until I understand the reason, I do not have the following value on account of the filter made by the user not return results when stamping the values within the code, but is it possible to treat this error? Like, put a 0 or something just so as not to interrupt reading the rest of my code?

This is my request, note the console.log trying to visualize the return and how the console returns the log:

$("#botao-filtrar").click(function(e){
    e.preventDefault();
    $.ajax({
        url: 'datacenter/functions/filtraDashboardGeral.php',
        async: true,
        type: 'POST',
        dataType: 'JSON',
        data: {rede: $("#dropdown-parceria").val(), codLoja: $("#dropdown-loja").val(), mes: $("#dropdown-mes").val()},
        success: function(data){
            console.log(data[1]['rede']);   
        }
    });

By default, data is an array that has an extension 3:

But sometimes, depending on the option selected by the user, it only returns one or two keys because it has no data for another key.

Following example:

And here is the PHP:

<?php
    session_start();
    require_once('../../includes/gestaoOriginacao.php');

    $rede = $_POST['rede'];
    $codLoja = $_POST['codLoja'];
    $mes = $_POST['mes'];
    $nomeCompleto = $_SESSION['nomeCompleto'];

    $dados = array();
    $query = retornaQueryGrafico($rede, $codLoja, $mes, $nomeCompleto);

    $resultado = mysqli_query($conexao, $query);

    while($valores = mysqli_fetch_assoc($resultado)){
         array_push($dados, $valores);
    }

    echo json_encode($dados);

    function retornaQueryGrafico($rede, $codLoja, $mes, $nomeCompleto){
        $hierarquia = $_SESSION['hierarquia'];
        if($hierarquia == 1){
            $query = "SELECT * FROM evolucao_originacao WHERE redeTratada = '{$rede}' and codLoja = '{$codLoja}' and mesReferencia = '{$mes}' and supervisor = '{$nomeCompleto}' order by mesReferencia";
        } else {
            $query = "SELECT * FROM evolucao_originacao WHERE redeTratada = '{$rede}' and codLoja = '{$codLoja}' and mesReferencia = '{$mes}' and supervisor = '9999999' order by mesReferencia";
        }
        return $query;
    };

Answer 1

From what I understand is not a PHP error, what is occurring is that probably depending on from query to variable data is coming empty [], then just make an IF to check:

$("#botao-filtrar").click(function(e){
    e.preventDefault();
    $.ajax({
        url: 'datacenter/functions/filtraDashboardGeral.php',
        async: true,
        type: 'POST',
        dataType: 'JSON',
        data: {rede: $("#dropdown-parceria").val(), codLoja: $("#dropdown-loja").val(), mes: $("#dropdown-mes").val()},
        success: function(data){
            if (data.length > 0) {
                //Atualiza a tela
            } else {
                //Exibe um alert(); ou outra coisa que avise que não retornou resultados
            }
        }
    });
});

Don’t forget to add the "error":, is good to check, can exchange for . done and . fail also:

$("#botao-filtrar").click(function(e){
    e.preventDefault();
    $.ajax({
        url: 'datacenter/functions/filtraDashboardGeral.php',
        async: true,
        type: 'POST',
        dataType: 'JSON',
        data: {rede: $("#dropdown-parceria").val(), codLoja: $("#dropdown-loja").val(), mes: $("#dropdown-mes").val()}
    }).done(function (data) {
        if (data.length > 0) {
            //Atualiza a tela
        } else {
            //Exibe um alert(); ou outra coisa que avise que não retornou resultados
        }
    }).fail(function (erro) {
        alert(erro);
    });
});

Answer 2

You can check if the property exists, in negative create one with a default value:

success: function(data){
    // verifica se é undefined
    if (!data[0]){
        data = [{rede: ''}]; // seta vazio para a propriedade rede do objeto no array
    }
}