Saving data from XMLHttpRequest Response to my IndexedDB - xmlhttprequest

Question

I have created a json file containing my Sql Server datas. With the XmlHttpRequest's GET method, I am reading json file and iterating and saving those records to my IndexedDB.. Everything is working fine.. After the end of the iteration, I wrote a code to alert the user.. But the alert message is displayed very quickly, but when I see it in the console window, the saving operation is till processing.. I want to alert the user, only after the operation is completed..
My code is,
if (window.XMLHttpRequest) {
var sFileText;
var sPath = "IDBFiles/Reservation.json";
//console.log(sPath);
var xhr = new XMLHttpRequest();
xhr.open("GET", sPath, 1);
xhr.onreadystatechange = function() {
if (xhr.readyState == 4 && xhr.status == 200) {
if (xhr.responseText != "") {
sFileText = xhr.responseText;
//console.log(sFileText);
var val = JSON.parse(sFileText);
var i = 0;
var value = val.length;
for(var i in val)
{
var code = val[i].RTM_res_category_code;
var desc = val[i].RTM_res_category_edesc;
addReserv(code, desc);
}
if(i >= value-1) {
console.log("Reservation Load Completed... "+i);
document.getElementById("status").innerHTML = "Reservation Loading Success...";
}
}
}
}
xhr.send();
}
//Passing Parameters to Reservation
function addReserv(code, desc)
{
document.querySelector("#status").innerHTML = "Loading Reservation.. Please wait...";
var trans = db.transaction(["Reservation"], "readwrite");
var store = trans.objectStore("Reservation");
//console.log(store);
var reserv={ RTM_res_category_code : code, RTM_res_category_edesc : ''+desc+'' };
var request = store.add(reserv);
request.onerror = function(e) {
console.log(e.target.error.name);
document.querySelector("#status").innerHTML = e.target.error.name;
}
request.onsuccess = function(e) {
console.log("Reservation Saved Successfully.");
//document.querySelector("#status").innerHTML = "Reservation Loaded Successfully.";
}
}

Answer 1

Thanks for the question.
What you are currently doing works, but the alert comes to soon because of the async nature of the IDB.
What you should to avoid this.
1. Create your transaction only once.
2. Do all your operations in this one transaction.
3. The transaction object has an oncomplete callback you can use to notify the user.
Concrete on your example. Instead of looping over the items in the ajax callback, pass the collection to your add method and loop there
if (window.XMLHttpRequest) {
var sFileText;
var sPath = "IDBFiles/Reservation.json";
//console.log(sPath);
var xhr = new XMLHttpRequest();
xhr.open("GET", sPath, 1);
xhr.onreadystatechange = function() {
if (xhr.readyState == 4 && xhr.status == 200) {
if (xhr.responseText != "") {
sFileText = xhr.responseText;
//console.log(sFileText);
var val = JSON.parse(sFileText);
import(val);
}
}
}
xhr.send();
}
function import(values)
{
document.querySelector("#status").innerHTML = "Loading Reservation.. Please wait...";
var trans = db.transaction(["Reservation"], "readwrite");
var store = trans.objectStore("Reservation");
var i = 0;
var value = val.length;
for(var i in val)
{
var code = val[i].RTM_res_category_code;
var desc = val[i].RTM_res_category_edesc;
var reserv={ RTM_res_category_code : code, RTM_res_category_edesc : ''+desc+'' };
var request = store.add(reserv);
request.onerror = function(e) {
console.log(e.target.error.name);
document.querySelector("#status").innerHTML = e.target.error.name;
}
request.onsuccess = function(e) {
console.log("Reservation Saved Successfully.");
//document.querySelector("#status").innerHTML = "Reservation Loaded Successfully.";
}
}
trans.oncomplete = function () {
console.log("Reservation Load Completed... "+i);
document.getElementById("status").innerHTML = "Reservation Loading Success...";
}
}