Warning: Invalid argument supplied for foreach () in C: \ xampp \ htdocs \ tccSistreinamento \ view \ modules \ student \ tmp \ listAluno.php on line 10

Probably the data passed in json_decode is not a valid JSON format string, so there must have been an error when decoding and will not work.

If the variable $obj is a string, it must contain a format such as:

$obj = '{...}';

If it came from a file probably the file read is invalid or it is in the wrong address, if $obj came from extract($_POST); this may be a flaw in your HTML form, anyway the problem is the JSON format.

And another detail, echo does not display the object, only displays number and strings or __toString , I recommend that you use var_dump

Sample test that works

I suppose the form should look like this:

<form action="listaluno.php" method="POST">
    <textarea name="obj">
    [
        {
            "StrNome": "Nome",
            "NumMatricula": 10000,
            "DtNascimento": "10/10/2001",
            "NumIdUop": 1
        },
        {
            "StrNome": "Foo Bar",
            "NumMatricula": 3000,
            "DtNascimento": "10/10/2002",
            "NumIdUop": 2
        }
    ]
    </textarea>
    <button>Enviar</button>
</form>

And then try clicking Send , it should work, the test resulted in:

JSONErrors

NotethattheremayhavebeenafailureintheformatofyourJSON,suchasanextracomma:

[{"StrNome": "Nome",
        "NumMatricula": 10000,
        "DtNascimento": "10/10/2001",
        "NumIdUop": 1
    },
    {
        "StrNome": "Foo Bar",
        "NumMatricula": 3000,
        "DtNascimento": "10/10/2002",
        "NumIdUop": 2
    }, <-------------------- Virgula extra
]

If there is any failure and do this:

<?php

$foo = '[
    {
        "StrNome": "Nome",
        "NumMatricula": 10000,
        "DtNascimento": "10/10/2001",
        "NumIdUop": 1
    },
    {
        "StrNome": "Foo Bar",
        "NumMatricula": 3000,
        "DtNascimento": "10/10/2002",
        "NumIdUop": 2
    },
]';

var_dump(json_decode($foo));

You will return this:

  

NULL

How to Debug JSON

If you are completely sure that your json was in the correct format, then redo your script like this:

<?php
extract($_POST);

$genList = json_decode($obj);

if (!$genList) {
    switch (json_last_error()) {
        case JSON_ERROR_DEPTH:
            echo 'A profundidade máxima da pilha foi excedida';
        break;
        case JSON_ERROR_STATE_MISMATCH:
            echo 'JSON malformado ou inválido';
        break;
        case JSON_ERROR_CTRL_CHAR:
            echo 'Erro de caractere de controle, possivelmente codificado incorretamente';
        break;
        case JSON_ERROR_SYNTAX:
            echo 'Erro de sintaxe';
        break;
        case JSON_ERROR_UTF8:
            echo 'Caractere UTF-8 malformado, codificação possivelmente incorreta';
        break;
        default:
            echo 'Erro desconhecido';
        break;
    }
    exit;
}

var_dump($genList);

?>
<table class= "table table-striped">
    <tbody>
        <thead>

        </thead>

        <?php foreach($genList as $aluno){ ?>

        <?php
        $scampos = $aluno->StrNome. "|".$aluno->NumMatricula. "|" .$aluno->DtNascimento. "|" .$aluno->NumIdUop;
        ?>

        <tr campos="<?php echo $scampos; ?>">

            <td><?php echo $aluno->StrNome; ?></td>
            <td><?php echo $aluno->NumMatricula; ?></td>
            <td><?php echo $aluno->DtNascimento; ?></td>
            <td><?php echo $aluno->NumIdUop; ?></td>
            <td><a href="#" class="editar_aluno"><span class="glyphicon glyphicon-pencil" title="Editar Aluno"></span></a></td>
            <td><a href="#" class="excluir_aluno"><span class="btTabela glyphicon glyphicon-trash" title="Excluir Aluno"></span></a></td>
        </tr>
    <?php } ?>

    </tbody>
</table>

  

Note: I have listed only a few errors, however in PHP7 there are more errors