Pagination doesn't work with datatables and nodejs/elasticsearch implementation - node.js

Question

I'm using nodejs as back/front-end implementation for a quick UI overview of an index in nodejs, and I'd like to use datatables with server side processing to display the data in a properly formated table.
It grabs all of the data fine, however it just dumps all of the records into one page on the table.
Model:
const { Client } = require('#elastic/elasticsearch')
const client = new Client({
node: '',
auth: {
username: '',
password: ''
}
})
module.exports = function getElasticData(callback/*, size*/) {
//parseInt(inputSize) = size;
client.search({
index: 'anomalies02_bhc-lstm2',
size: 10000,
body: {
query: {
match_all: {}
}
}
}, function (error, response, status) {
if (error) {
console.log("search error: " + error)
}
if (response) {
var elasticList = [];
//console.log("EL:" + JSON.stringify(response))
response.body.hits.hits.forEach(function (hit) {
elasticList.push(hit);
})
//callback(elasticList.sort());
//console.log("SORTED LIST: " + JSON.stringify(elasticList))
callback(elasticList);
}
else {
console.log("<p>No results</p>");
}
});
}
Controller:
var elasticDataModel = require('../model/getDataElastic');
exports.getData = function (req, res) {
elasticDataModel(function (elasticList) {
var searchStr = req.body.search.value;
var recordsTotal = 0;
var recordsFiltered = 0;
var size = parseInt(req.body.length);
var recordsFiltered = elasticList.slice(0, size)
console.log("LENGTH: " + JSON.stringify(req.body.length))
console.log("FILTERED: " + JSON.stringify(recordsFiltered))
//console.log(elasticList[0]._source);
console.log(typeof parseInt(req.body.draw))
console.log(elasticList.length)
recordsTotal = elasticList.length;
//console.log("DRAW " + req.body.draw);
var data = JSON.stringify({
"data": elasticList,
"draw": parseInt(req.body.draw),
"recordsTotal": recordsTotal,
"recordsFiltered": recordsFiltered
});
res.send(data);
});
}
HTML:
$(document).ready(function () {
var t = $('#example2').DataTable({
"paging": true,
"processing": true,
"serverSide": true,
'ajax': {
'type': 'POST',
'url': '/populateData'
},
'pageLength': 20,
'lengthMenu': [5, 10, 20, 50, 100, 200, 500],
'columns':
[
{ 'data': '_id', "defaultContent": "", 'name': 'ID' },
{ "defaultContent": "", 'name': 'Kibana Link' },
{ 'data': '_source.Environment', "defaultContent": "", 'name': 'Environment' },
{ 'data': '_source.Cause', "defaultContent": "", 'name': 'Downtime cause' },
{ 'data': '_source.Start', "defaultContent": "", 'name': 'Detected start' },
{ 'data': '_source.End', "defaultContent": "", 'name': 'Detected end' },
{ "defaultContent": "", 'name': 'Actual start' },
{ "defaultContent": "", 'name': 'Actual end' },
{ "defaultContent": "", 'name': 'Reason category' },
{ "defaultContent": "", 'name': 'Reason details' },
{ "defaultContent": "", 'name': 'Submit' },
],
"columnDefs": [
{
"searchable": true,
"orderable": true,
"targets": 0
}
]
});
});

Answer 1

I modifed my code accordingly with help from Kevin at the datatables forums and now it works flawlessly.
Changed code:
Controller
var elasticDataModel = require('../model/getFilteredDataElastic');
var pageLength;
var pageStart;
exports.getData = function (req, res) {
pageLength = req.body.length;
pageStart = req.body.start
console.log("MODEL Length: " + pageLength)
elasticDataModel(pageLength, pageStart, function (elasticFilteredList) {
var searchStr = req.body.search.value;
var recordsTotal = 0;
var recordsFiltered = 0;
console.log("PAGE LENGTH: " + pageLength)
if (req.body.search.value) {
var regex = new RegExp(req.body.search.value, "i")
searchStr = { $or: [{ '_id': regex }, { 'Environment': regex }, { 'Downtime cause': regex }, { 'Detected start': regex }, { 'Detected end': regex }, { 'Reason details': regex }] };
}
else {
searchStr = {};
}
var size = parseInt(req.body.length);
var recordsFiltered = elasticFilteredList
var data = JSON.stringify({
"data": elasticFilteredList,
"draw": parseInt(req.body.draw),
"recordsTotal": elasticFilteredList[0],
"recordsFiltered": recordsFiltered
});
res.send(data);
});
}
Model:
const { Client } = require('#elastic/elasticsearch')
const client = new Client({
node: '',
auth: {
username: '',
password: ''
}
})
module.exports = function getElasticData(arg, arg2, callback) {
console.log("CONTROLLER SIZE: " + arg)
console.log("CONTROLLER FROM: " + arg2)
client.search({
index: 'anomalies02_bhc-lstm2',
from: arg2,
size: arg,
body: {
query: {
match_all: {}
}
}
}, function (error, response, status) {
if (error) {
console.log("search error: " + error)
}
if (response) {
var elasticFilteredList = [];
console.log("VALUE: " + response.body.hits.total.value);
elasticFilteredList.push(response.body.hits.total.value);
response.body.hits.hits.forEach(function (hit) {
elasticFilteredList.push(hit);
})
callback(elasticFilteredList);
}
else {
console.log("<p>No results</p>");
}
});
}