Correct way of converting a CSV to JSON array

Question

I have a "Student" object/model created in PHP and I use its setter methods to set its fields with the values on each cell from CSV per row. I'm having troubles parsing the array of students to a JSON object.

read_student_csv.php

echo json_encode(getPopulatedStudentCSV());// doesn't seem to parse correctly

function getPopulatedStudentCSV(){

$studentList = [];
$csvFile = $_FILES["csvFile"]["tmp_name"];

$student_csv_temp_file_location = $_FILES["csvFile"]["tmp_name"];
$row = 1;
$handle = fopen($student_csv_temp_file_location, "r");
    if ($handle !== FALSE) {
        while (($data = fgetcsv($handle, 1000, ",")) !== FALSE) {
            $rowCellCount = count($data);
            //echo "<p> $rowCellCount fields in row: $row: <br /></p>\n";
            $row++;
            $student = new Student();
            for ($cell=0; $cell < $rowCellCount; $cell++) {
                if($row != 2){
                    if($cell == 0) //student number
                    {
                        $student->setStudentNo($data[$cell]);
                    }
                    else if($cell == 1) //student last name
                    {
                        $student->setLastName($data[$cell]);
                    }
                    else if($cell == 2) //student first name
                    {
                        $student->setFirstName($data[$cell]);
                    }
                    else if($cell == 3) //student middle name
                    {
                        $student->setMiddleName($data[$cell]);
                    }
                }
            }
            $studentList[] = $student;
        }
        fclose($handle);
    }
    return $studentList;
}

jsfile

function displayCSVPreview(){
    var csvFile =  $('#browseFiles')[0].files[0];
    var formData = new FormData();
    formData.append('csvFile', csvFile);

    //alert("FormData: "+formData);
    $.ajax({
        url: 'script/read_student_csv.php',
        type: 'POST',
        data: formData,
        processData: false,  // tell jQuery not to process the data
        contentType: false,  // tell jQuery not to set contentType
        success: function (students) {
            console.log("Students : " + students);

            console.log("Length: "+ students.length);

            for(var i = 1; i < students.length; i++){
                $('#studentcsvpreviewtable').append(
                    "<tr>"+
                    "<td>" + students[i] +"</td>" +
                    "<td>" + students[i]['lastName'] + "</td>" +
                    "<td>" + students[i]['firstName'] + "</td>" +
                    "<td>" + students[i]['middleName'] + "</td>" +
                    "</tr>"
                );
            }

        },
        error: function (x, e) {
            handleError(x,e);
        }
    });
}

student[i] returns every single character of the value returned by the response from read_student_csv.php's getPopulatedStudentsCSV() function.

If I do student[i]['lastName'], I get an "undefined" value.

I don't know how to properly parse the $studentList[] to a JSON with keys and values. json_encode() doesn't seem to do it correctly.

The two lines below returns

console.log("Students : " + students); 
console.log("Length: "+ students.length);

Students : [{"studentNo":null,"lastName":null,"firstName":null,"middleName":null},{"studentNo":"12345","lastName":"Doe","firstName":"John Sam","middleName":"Man"},{"studentNo":"23456","lastName":"Nuggets","firstName":"Ashton","middleName":"Alvin"}]

Length: 256

Shows length of 256 because I think it counts every single character from the output. Which isn't correct.

I'd appreciate any suggestion.

Thank you.