How to add an object inside stdClass() and print the json

Question

How do I add a variable or object within a json. It is thus printing my json:

{"Registros":[{"RegistroOperacaoID":"39","Tipo":"11","DataOperacao":"2019-03-27 16:29:36","AlunoID":null,"ResponsavelID":"57","CursoID":"327","MatriculaID":null,"PlanoID":"68","Processado":"0","Nome":null}

I would like to add together with this data another variable or object, that would be like this:

{"Registros":[{"RegistroOperacaoID":"39","Tipo":"11","DataOperacao":"2019-03-27 16:29:36","AlunoID":null,"ResponsavelID":"57","CursoID":"327","MatriculaID":null,"PlanoID":"68","Processado":"0","variavel":"1 registro","Nome":null}

my php code looks like this:

register.operacao.php

$sql = "SELECT R.RegistroOperacaoID, R.Tipo, R.DataOperacao, R.AlunoID, R.ResponsavelID, R.CursoID, R.MatriculaID, R.PlanoID, R.Processado, A.Nome FROM {$pfx}Registrooperacoes R LEFT JOIN {$pfx}Aluno A ON (A.AlunoID = R.AlunoID) WHERE Processado = 0";

    $qry = $database->query($sql);
    $listaOperacoes = array();
    $ctaOperacoes = 0;
    if($qry){
        while ($row = fetch($qry)) {
            $listaOperacoes[] = $row;            
            $ctaOperacoes++;           
        }
    }

    @$output = new StdClass();
    //$variavel = "$ctaOperacoes registros";        
    $output->Registros = $listaOperacoes;    

    $saida = json_encode($output, JSON_UNESCAPED_UNICODE);
    echo $saida;

Answer 1

Hello, to add a value is simple, but you do not add directly in json, notice that in your code is creating an object and the variable $saida is receiving this converted object in json, what we need to do is to place new attribute or object inside $output before printing the json.
Where will we work on your code.

    @$output = new StdClass();
    //$variavel = "$ctaOperacoes registros";

    //Vamos trabalhar aqui

    $output->Registros = $listaOperacoes;

    $saida = json_encode($output, JSON_UNESCAPED_UNICODE);
    echo $saida;

To $listaOperacoes is an array of objects, so to make the insertion we need to have the key($key) of each item, thus foreach we will help solve the problem.
The novoAtributo (can have any name) is the attribute we are creating inside an object of $listaOperacoes. The way to place this new variable is as follows.

    foreach ($listaOperacoes as $key => $value) {
        $listaOperacoes[$key]->novoAtributo = 'Eu sou um novo valor dentro do registro';
    }

Your code should be as follows friend.

    @$output = new StdClass();
    //$variavel = "$ctaOperacoes registros";    

    foreach ($listaOperacoes as $key => $value) {
        $listaOperacoes[$key]->novoAtributo = 'Eu sou um novo valor dentro do 
    registro';
    }

    $output->Registros = $listaOperacoes;    

    $saida = json_encode($output, JSON_UNESCAPED_UNICODE);
    echo $saida;