PHP: can't encode json with multiple rows

Question

I\'ve spent a couple of hours looking through several the similar answers before posting my problem.

I\'m retrieving data from a table in my database, and I want to

Answer 1

The problem is you're spitting out separate JSON for each row, as opposed to doing it all at once.

$result = mysql_query($query);

$rows = array();

//retrieve and print every record
while($r = mysql_fetch_assoc($result)){
    // $rows[] = $r; has the same effect, without the superfluous data attribute
    $rows[] = array('data' => $r);
}

// now all the rows have been fetched, it can be encoded
echo json_encode($rows);

The minor change I've made is to store each row of the database as a new value in the $rows array. This means that when it's done, your $rows array contains all of the rows from your query, and thus you can get the correct result once it's finished.

The problem with your solution is that you're echoing valid JSON for one row of the database, but json_encode() doesn't know about all the other rows, so you're getting a succession of individual JSON objects, as opposed to a single one containing an array.

Answer 2

You need to change your PHP code into something like this:

$result = mysql_query($query);

$rows = array();

//retrieve every record and put it into an array that we can later turn into JSON
while($r = mysql_fetch_assoc($result)){
    $rows[]['data'] = $r;
}
//echo result as json
echo json_encode($rows);

Answer 3

I was trying the same in my PHP, so I came whit this...

$find = mysql_query("SELECT Id,nombre, appaterno, apmaterno, semestre, seccion, carrera FROM Alumno");

    //check that records exist
    if(mysql_num_rows($find)>0) {
        $response= array();
        $response["success"] = 1;

        while($line = mysql_fetch_assoc($find)){}
             $response[] = $line; //This worked for me
        }

        echo json_encode($response);

    } else {
        //Return error
        $response["success"] = 0;
        $response["error"] = 1;
        $response["error_msg"] = "Alumno could not be found";
        echo json_encode($response);
    }

And, in my Android Class...

if (Integer.parseInt(json.getString("success")) == 1) {

                    Iterator<String> iter = json.keys();
                    while (iter.hasNext()) {
                        String key = iter.next();
                        try {
                            Object value = json.get(key);
                            if (!value.equals(1)) {

                                JSONObject jsonArray = (JSONObject) value;

                                int id = jsonArray.getInt("Id");
                                if (!db.ExisteAlumo(id)) {
                                    Log.e("DB EXISTE:","INN");
                                    Alumno a = new Alumno();

                                    int carrera=0;
                                    a.setId_alumno(id);
                                    a.setNombre(jsonArray.getString("nombre"));
                                    a.setAp_paterno(jsonArray.getString("appaterno"));
                                    a.setAp_materno(jsonArray.getString("apmaterno"));
                                    a.setSemestre(Integer.valueOf(jsonArray.getString("semestre")));
                                    a.setSeccion(jsonArray.getString("seccion"));
                                    if(jsonArray.getString("carrera").equals("C"))
                                        carrera=1;
                                    if(jsonArray.getString("carrera").equals("E"))
                                        carrera=2;
                                    if(jsonArray.getString("carrera").equals("M"))
                                        carrera=3;
                                    if(jsonArray.getString("carrera").equals("S"))
                                        carrera=4;
                                    a.setCarrera(carrera);

                                    db.addAlumno(a);

                                }

                            }
                        } catch (JSONException e) {
                            // Something went wrong!
                        }

                }

Answer 4

I must have spent 15 hours on this issue. Every variation discussed above was tried. Finally I was able to get the 'standard solution' working. The issue, very oddly, appears to be this:

When the interval is set beyond 14 hours, json appears to be unable to parse it. There must be a limit to JSON.

$sql= "SELECT cpu_name, used, timestamp FROM tbl_cpu_use WHERE timestamp>(NOW() - INTERVAL 14 HOUR) ORDER BY id";
$result=mysql_query($sql);
if ($result){
    $i=0;
    $return =[];
    while($row = mysql_fetch_array($result, MYSQL_NUM)){
        $rows[] = $row;
    }
    echo json_encode($rows);
}else{
    echo "ERROR";
}

Answer 5

I think you should do

$rows = array();
while($r = mysql_fetch_assoc($result)){
    $rows[]['data'] = $r;
}
echo json_encode($rows);

echo should be placed outside of the loop.