CRUD gsheet

// ketentuan = header pada baris ke 2, kolom A B C D dan E berisi tgl
// isi pada baris ke 3 dst
function doGet(e) {
    var op = e.parameter.action;
    var ss = SpreadsheetApp.openByUrl("https://docs.google.com/spreadsheets/d/xxx/edit#gid=xxx");
    var sheet = ss.getSheetByName("Sheet1");

    if (op == "insert")
        return insert_value(e, sheet);
    //Make sure you are sending proper parameters
    if (op == "read")
        return read_value(e, sheet);
    if (op == "update")
        return update_value(e, sheet);
    if (op == "delete")
        return delete_value(e, sheet);
    if (op == "readAll")
        return read_all_value(e, ss);
}

// pada kolom header harus sesuai dengan isi cell, contoh dlm hal ini = id, name, alamat, tonase
function insert_value(request, sheet) {
  var id = request.parameter.id;
  var name = request.parameter.name;
  var alamat = request.parameter.alamat;
  var tonase = request.parameter.tonase;

  var flag = 1;
  var lr = sheet.getLastRow();
    for (var i = 1; i <= lr; i++) {
    //mencari kolom 1
        var id1 = sheet.getRange(i, 1).getValue();
        if (id1 == id) {
            flag = 0;
            var result = "Id already exist..";
        }
    }
    //add new row with recieved parameter from client
    if (flag == 1) {
        var d = new Date();
        var currentTime = d.toLocaleString();
        var numcols = sheet.getLastColumn();
        var rowData = sheet.appendRow([id,name,alamat,tonase,currentTime]);
        var result = "Insertion successful";
    }
    result = JSON.stringify({
        "result": result
    });

    return ContentService
        .createTextOutput(result)
        .setMimeType(ContentService.MimeType.JAVASCRIPT);
}

function read_all_value(request, ss) {
    var output = ContentService.createTextOutput(),
        data = {};
    //Note : here sheet is sheet name , don't get confuse with other operation
    var sheet = "Sheet1";
    data.records = readData_(ss, sheet);
    var callback = request.parameters.callback;
    if (callback === undefined) {
        output.setContent(JSON.stringify(data));
    } else {
        output.setContent(callback + "(" + JSON.stringify(data) + ")");
    }
    output.setMimeType(ContentService.MimeType.JAVASCRIPT);
    return output;
}

function readData_(ss, sheetname, properties) {
    if (typeof properties == "undefined") {
        properties = getHeaderRow_(ss, sheetname);
        properties = properties.map(function(p) {
            return p.replace(/\s+/g, '_');
        });
    }
    var rows = getDataRows_(ss, sheetname),
        data = [];
    for (var r = 0, l = rows.length; r < l; r++) {
        var row = rows[r],
            record = {};
        for (var p in properties) {
            record[properties[p]] = row[p];
        }
        data.push(record);
    }
    return data;
}

function getDataRows_(ss, sheetname) {
    var sh = ss.getSheetByName(sheetname);
    //lihat baris ke3
    return sh.getRange(3, 1, sh.getLastRow() - 2, sh.getLastColumn()).getValues();
}

function getHeaderRow_(ss, sheetname) {
    var sh = ss.getSheetByName(sheetname);
    //lihat baris ke2
    return sh.getRange(2, 1, 1, sh.getLastColumn()).getValues()[0];
}

//update function

function update_value(request, sheet) {
    var output = ContentService.createTextOutput();
    var id = request.parameter.id;
    var flag = 0;
    var name = request.parameter.name;
    var alamat = request.parameter.alamat;
    var tonase = request.parameter.tonase;

    var lr = sheet.getLastRow();
    for (var i = 1; i <= lr; i++) {
    //lihat kolom ke satu
        var rid = sheet.getRange(i, 1).getValue();
        if (rid == id) {
            sheet.getRange(i, 2).setValue(name);
            sheet.getRange(i, 3).setValue(alamat);
            sheet.getRange(i, 4).setValue(tonase);
            var result = "value updated successfully";
            flag = 1;
        }
    }
    if (flag == 0)
        var result = "id not found";

    result = JSON.stringify({
        "result": result
    });

    return ContentService
        .createTextOutput(result)
        .setMimeType(ContentService.MimeType.JAVASCRIPT);
}

function delete_value(request, sheet) {
    var output = ContentService.createTextOutput();
    var id = request.parameter.id;
    var name = request.parameter.name;
    var alamat = request.parameter.alamat;
    var tonase = request.parameter.tonase;

    var flag = 0;

    var lr = sheet.getLastRow();
    for (var i = 1; i <= lr; i++) {
    //lihat kolom ke satu
        var rid = sheet.getRange(i, 1).getValue();
        if (rid == id) {
            sheet.deleteRow(i);
            var result = "value deleted successfully";
            flag = 1;
        }
    }
    if (flag == 0)
        var result = "id not found";
    result = JSON.stringify({
        "result": result
    });

    return ContentService
        .createTextOutput(result)
        .setMimeType(ContentService.MimeType.JAVASCRIPT);
}

function read_value(request, sheet) {
  var id = request.parameter.id;
  var name;
  var alamat;
  var tonase;

var record = {};
    //var place = request.parameter.place;
    var flag = 1;
    var lr = sheet.getLastRow();
    for (var i = 1; i <= lr; i++) {
    // lihat kolom ke satu
        var id1 = sheet.getRange(i, 1).getValue();
        if (id1 == id) {
            flag = 0;
            name = sheet.getRange(i, 2).getValue();
            alamat = sheet.getRange(i, 3).getValue();
            tonase = sheet.getRange(i, 4).getValue();
            var result = JSON.stringify({
                "user": {
                    "id": id,
                    "name": name,
                    "alamat": alamat,
                    "tonase": tonase
                }
            });
        }
    }
    return ContentService
        .createTextOutput(result)
        .setMimeType(ContentService.MimeType.JAVASCRIPT);
}