Develop Reference

How to access javascript code from a controller in an Asp.Net Core MVC application

I have an Asp.Net Core MVC application that searches youtube videos and returns a list that is displayed on screen. Each video is placed in a custom component that has a checkbox. Every time a checkbox is selected I access a script that searches all the video components that are on the screen and I store the video id's in a list in my .cshtml page.
At some point I need to get this list of video id's to do a processing. For that I created a javascript method in the same .cshtml page to return this list of ids.
I've already done a research on JSRuntime on Blazor (.razor) pages but that wouldn't be my case.
The fact is that with the click of a button I need to call a controller method, and this method calls my javascript method which returns my list of ids.
How best to do this?
This my javascript code.
#section scripts
{
<script>
var listaDeIds = [];
function Mostrar() {
//document.getElementById("btnplaylist").style.display = 'block';
var videos = document.querySelectorAll('#video');
var count = 0;
var lista = [];
for (var i = 0; i < videos.length; i++) {
//console.log("1 - " + videos.item(i).getAttribute("name"));
var videoID = videos.item(i).getAttribute("name");
//console.log("2 - " + videos.item(i).getAttribute("id"));
const shadow = videos.item(i).shadowRoot;
const childNodes = Array.from(shadow.childNodes);
//console.log("3 - " + childNodes.length);
childNodes.forEach(childNode => {
if (childNode.nodeName === "DIV") {
//console.log("4 - " + childNode.nodeName);
const shadowChilds = Array.from(childNode.childNodes);
//console.log("5 - " + shadowChilds.length);
shadowChilds.forEach(shadowShild => {
if (shadowShild.nodeName === "DIV") {
//console.log("6 - " + shadowShild.nodeName);
const shadowChildsInternas = Array.from(shadowShild.childNodes);
//console.log("7 - " + shadowChildsInternas.length);
shadowChildsInternas.forEach(interna => {
if (interna.nodeName === "INPUT") {
//console.log("8 - Name " + interna.nodeName);
if (interna.checked === true) {
//console.log("9 - Checked: " + interna.checked);
lista[count] = videoID;
count = count + 1;
}
}
});
}
});
}
});
}
if (lista.length > 0) {
document.getElementById("btnplaylist").style.display = 'block';
} else {
document.getElementById("btnplaylist").style.display = 'none';
}
listaDeIds = lista;
}
function RetornaListaDeIds() {
return listaDeIds;
}
</script>
This is my html component code
<custom-iframe id="video" name="#item.Id.VideoId" urlvideo='#Url.Content(item.Url)' onclick="Mostrar()"></custom-iframe>
This is the button that calls my controller.
<div id="btnplaylist" class="right_side hidden">
<button value="Playlist" asp-controller="VideoSearch" asp-action="GravarSelecionados" class="btn green-button button-tamanho-padrao">Playlist</button>
</div>
Code of my control.

I think you might be missing something at a high level here so bear with me.
Your use case is you want users to 'check' videos that you serve to them via a web app, visually altering the page elements around the videos and ultimately sending them off for processing, which I assume means some kind of storage or at least some back-end work.
If I understand your attempted solution to this problem correctly, it is impossible. Even if you did get your backend to run javascript, it wouldn't be aware of the client's state and could not read that list of videos off of it. There's no reason for javascript to run on your server as I see it.
Instead, you need your client-side Javascript to send that list of ids to your server via an API in a JSON format. The flow goes (user checks box -> JS on the browser collects the id of that video and formats a POST request with some json describing what was checked -> that JSON is sent to your server which then reads it an processes it)
The frontend javascript and the server should always communicate with eachother in this way. Again, there's no need for javascript to be run on the server itself.

Moving on to thank everyone who gave suggestions for solving my problem for their support. I followed and tested all the suggestions and the one that fit best to my problem was the use of ajax, suggested by #Andre.Santarosa.
I followed the following article as a reference:http://www.macoratti.net/15/05/mvc_ajax.htm
I installed the package: Microsoft.jQuery.Unobtrusive.Ajax
I added the script reference in my _Layout.cshtml:
<script src="~/lib/jquery-validation-unobtrusive/jquery.validate.unobtrusive.js"></script>
On the page that lists the videos, the code looks like this:
Button code:
<div id="btnplaylist" class="right_side hidden">
<input type="button" value="Playlist" id="Playlist" class="btn green-button button-tamanho-padrao" />
</div>
Ajax Code:
$('#Playlist').click(function () {
var url = "/VideoSearch/PegarListaDeIds";
var lista = listaDeIds;
$.post(url, { pListaDeIds: lista }, function (data) {
$("#msg").html(data);
});
});

Remove query string on page reload

I have a hyperlink which i am redirecting to a page.
$('.lnkMerging').on("click", function () {
var id = $(this).attr('data-id');
window.location = '/Merging/Index/?workItemID=' + id;
});
My action in the controller page is
public ActionResult Index(int? workItemID)
{
MergingVM mergingVM = new MergingVM();
mergingVM.SourceList = GetSourceDropdownList();
mergingVM.WorkItem = (workItemID==null? 0: workItemID.Value) ;
mergingVM.MergeActionSelectList =
GetMergeProcessActionDropdownList();
PopulateDropDowns(mergingVM);
return View(mergingVM);
}
So what it does is when i click on the hyperlink it redirects me to the merging page.
After redirecting to Merge page, the drop down fills with id(selected in home page) and correspondingly triggers the button click.
My issue When i reload the merge page the value in the drop down doesn't get clear. I.e if i have redirected from home page to merge page , then the drop down has some value. but when i refreshes it the selected value should go. I understand that the query string still holds the value. But is there any alternative to send parameter to action without using windows.location.href in jquery.

If you are using hyperlink then also you can try it
$('.lnkMerging').on("click", function () {
var id = $(this).attr('data-id');
$(this).attr('href','/Merging/Index/?workItemID=' + id)
});

In order to clean the query string you should use redirect to another view.
public ActionResult Index(int? workItemID)
{
MergingVM mergingVM = new MergingVM();
mergingVM.SourceList = GetSourceDropdownList();
mergingVM.WorkItem = (workItemID == null ? 0 : workItemID.Value);
mergingVM.MergeActionSelectList =
GetMergeProcessActionDropdownList();
PopulateDropDowns(mergingVM);
//to send this model to the redirected one.
TempData["model"] = mergingVM;
return RedirectToAction("CleanIndex");
}
public ActionResult CleanIndex()
{
var model = (MergingVM)TempData["model"] ?? new MergingVM();
// Do something
return View("Index", model);
}
To find alternatives to an send parameter to a method you first need to understand the model Bindding action.
The model bidding searches a value in:
Form Data
Route Data
Query String
Files
Custom (cookies for example)
If your action must need to be HttpGet you lose the Form Data which would be a nice alternative for you.

If I understand correctly... the below worked for me.
If there's an ID appended to the URL, it gets logged to the console as the variable "param". The URL is then replaced (so that if you refresh the page, the ID is removed from the URL).
$(document).ready(function() {
var url = window.location.toString;
var hostname = window.location.hostname;
var pathname = window.location.pathname;
var param = window.location.search;
$('.lnkMerging').on("click", function () {
var id = $(this).attr('data-id');
window.location = '/new-page.php?' + id;
});
if ( pathname == "/new-page.php" && param ) {
console.log(param);
window.history.pushState("string", "Title", "http://yourURL.com/new-page.php");
//Do something with param...
}
});
This assumes that if there is no ID appended to the URL, the drop-down won't do anything. You also would need to update the URLs to the correct ones (I ran this on my local server).

I think you should use POST where you don't want to presist workItemID.
I mean all places where you have links you should use somethink like this:
<form action="/Merging/Index" method="POST">
<input type="hidden" name="workItemID" value="1" /> <-- your Id
<input type="submit" value="Link to workItemID 1!" /> <-- your link
</form>
This way you will get your View but without workItemID in URL. But you should change css to make your POST link look like <a> tags.
Here is with your table:
#if (#Model.DataSetList[i].StateID == 43)
{
<td>
<form action="/Merging/Index" method="POST">
<input type="hidden" name="workItemID" value="#Model.DataSetList[i].Workitem_ID" />
<input class="lnkMerging" type="submit" value="Merging" />
</form>
</td>
}
else
{
<td>
<text style="color:darkgrey" contenteditable="false">Merging</text>
</td>
}

You can save the parameter in local storage api of html5, and then use those parameters in Page load of index page.
$('.lnkMerging').on("click", function () {
var id = $(this).attr('data-id');
localStorage.setItem("workItemID",id);
window.location = '/Merging/Index/;
});
On page load of index you can retrieve it using getItem
localStorage.getItem("workItemID"); and use it as per your requirement.
On page load of Merge page, you have to explicitly set the selected option like below and then remove the value from local storage.
$(document).ready(function(){
if(localStorage.getItem("workItemID")!=null){
$("#mydropdownlist").val(localStorage.getItem("workItemID"));
localStorage.removeItem('workItemID');
}
});
Make sure in var id = $(this).attr('data-id'); id should get same value as you have in the options on the merge page.

Calling an Action Method based on the value of DropDownList and the model

I have a dropdownlist in my View. I need to enable the user to select a value from the dropdownlist and click a button/ActionLink to call another action method in the same controller. The values that needs to be passed to the new ActionMethod are the ID of the selected Value from the dropdownlist and also the ID of the model which is being passed into the View. The model and the Dropdownlist are not linked together by any means.
I have tried onchnage = document.location.href to set the path of the action method and pass a single value to the action method. But the issue with document.location.href is that it appends the url to the existing url which is not appreciated; i.e, the final url turns out be localhost:port/controller1/action1/controller1/action2 which should have been simply localhost:port/controller1/action2
I am looking for a way where it could be done without using javascript as I have already tried it.
Code in the View
#using (Html.BeginForm("Copy","SetValues",FormMethod.Post))
{
<p>
#Html.DropDownList("OptionValueID", null, "Select")
<input type="submit" value="Copy" />
//This is the preferable method though
#*#Html.ActionLink("Copy", "Copy", "SetValues", new { #OptionValueID = #ViewBag.id,#CopyID = CopyDDL.SelectedValue},null)*#
</p>
}
The copy function is going to take two arguments: Id of the selected item and ID that is being passed through ViewBag.id
The View that is being returned by View would a different View
JavaScript that I have tried
<script language="javascript" type="text/javascript">
function copy(_OptionValueID)
{
var url = "/SetValues/Copy";
$.ajax({
url: url,
data: { copyid: _OptionValueID},
type: "POST",
success: function (data) { }
});
response();
}
</script>
It doesn't evaluate at all.
Action Method that calls this View
public ActionResult Index(int id)
{
var ov = db.OptionValue.Include(x => x.Option).FirstOrDefault(x => x.OptionValueID == id);
var opid = ov.OptionID;
var op = db.Option.Include(x => x.TechnicalCharacteristic).FirstOrDefault(x => x.OptionID == opid);
var tcid = op.TechnicalCharacteristicID;
var tc = db.TechnicalCharacteristic.Include(x => x.TcSets).FirstOrDefault(x => x.TechnicalCharacteristicID == tcid);
var tcset = tc.TcSets;
var opv = db.OptionValue.FirstOrDefault(x => x.OptionValueID == id);
ViewBag.OptionValue = opv.OptionVal;
ViewBag.Option = opv.Option.OptionName;
ViewBag.Lsystem = opv.Option.Lsystem.LsystemName;
ViewBag.FamilyName = opv.Option.Lsystem.LsystemFamily.FamilyName;
ViewBag.OptionValID = id;
ViewBag.OptionID = opv.OptionID;
var setValue = db.SetValue.Where(x=>x.OptionValueID==id).OrderBy(x=>x.TcSet.SetName);
ViewBag.OptionValueID = new SelectList(db.OptionValue.Where(x=>x.OptionID==opid), "OptionValueID", "OptionVal");
return View(setValue.ToList());
}
I ahve checked most question relating to this, but none had the overhead of passing two parameters without using a model.
UPDATE: making it more clear
public ActionResult copy(int OptionValueID,int CopyID)
{
//do Something
return View("Error");
}
Above is the Copy Method
OptionValueID = ViewBag.OptionValID //Got from the Action Method Index of SetValues
CopyID = Value from the DropDownlist
Edit Based on Answer
#using (Html.BeginForm("Copy","SetValues",FormMethod.Post))
{
<p>
#Html.DropDownList("CopyID", null, "Select")
<button type="submit" id="Copy" data-id="#ViewBag.OptionValID"> Copy </button>
</p>
}
now the page is being redirected but the no parameters are being passed. Should I be adding routevalues?

You cannot do it without javascript. Your ActionLink() method is parsed on the server before its sent to the client, so any route values are the initial values in the controller, not any edited values the user makes in the view. In order to respond to client side events you need javascript.
You can use ajax to post the values to the server method.
Include a button and handle its click event
<button type="button" id="Copy" data-id="#ViewBag.id">Copy</button>
Script
var url = '#Url.Action("Copy", "SetValues")';
$('#Copy").click(function() {
var optionID = $(this).data('id');
var copyID = $('#OptionValueID').val();
$.get(url, { OptionValueID: optionID, copyID : CopyID }, function(response) {
// do something with the response
});
});
or alternatively if you wanting to redirect, then replace the $.get() with
location.href = url + '?OptionValueID=' + optionID + '&CopyID=' + copyID;
Edit
Based on revised question and comments, if you wanting to post and redirect, there is no need for any javascript or the link. The dropdownlist needs to be #Html.DropDownList("CopyID", null, "Select") so that its selected value is bound to method parameter int CopyID and since the OptionValueID is not edited, then either add its value as a route parameter in the form
#using (Html.BeginForm("Copy", "SetValues", new { OptionValueID = ViewBag.OptionID }, FormMethod.Post))
or add a hidden input for the value
<input type="hidden" name="OptionValueID" value="#ViewBag.OptionID" />

ngInit not working asynchronously(with $q promise)

Edit:
Plunker is working, actual code isn't:
http://plnkr.co/edit/5oVWGCVeuTwTARhZDVMl?p=preview
The service is contains typical getter\setter stuff, beside that, it functions fine, so I didn't post it's code to avoid TLDR.
TLDR version: trying to ng-init a value fetched with AJAX into the ngModel of the text-area, the request resolves with the correct value, but the textarea remain empty.
parent controller function(talks to the service):
$scope.model.getRandomStatus = function(){
var deffered = $q.defer();
var cid = authService.getCompanyId();
var suggestions = companyService.getStatusSuggestions(cid);
if(suggestions && suggestions.length > 0){
deffered.resolve(suggestions[Math.floor(Math.random(suggestions.length) + 1)].message);
return deffered.promise;//we already have a status text, great!
}
//no status, we'll have to load the status choices from the API
companyService.loadStatusSuggestions(cid).then(function(data){
companyService.setStatusSuggestions(cid, data.data);
var result = data.data[Math.floor(Math.random(data.data.length) + 1)];
deffered.resolve(result.message);
},
function(data){
_root.inProgress = false;
deffered.resolve('');
//failed to fetch suggestions, will try again the next time the compnay data is reuqired
});
return deffered.promise;
}
child controller:
.controller('shareCtrl', function($scope){
$scope.layout.toggleStatusSuggestion = function(){
$scope.model.getRandomStatus().then(function(data){
console.log(data);//logs out the correct text
//$scope.model.formData.shareStatus = data;//also tried this, no luck
return data.message;
});
$scope.model.formData.shareStatus = $scope.layout.toggleStatusSuggestion();//Newly edited
}
});
HTML:
<div class="shareContainer" data-ng-controller="shareCtrl">
<textarea class="textAreaExtend" name="shareStatus" data-ng-model="model.formData.shareStatus" data-ng-init="model.formData.shareStatus = layout.toggleStatusSuggestion()" cols="4"></textarea>
</div>

I believe what you are wanting is :
$scope.model.getRandomStatus().then(function(data){
$scope.model.formData.shareStatus = data.message;
});
Returning something from within then does not return anything from the function wrapping it and therefore does nothing

Turns out that I had a custom validation directive that was watching the changes in the model via $formatters, and limting it to 80 chars(twitter), it was failing silently as I didn't expect to progmatically insert invalid values into my forms, very stupid, but could happen to anyone.
Had to make some changes to it, so it's worth to remember in case it happens to anyone else.

Appending an Array and String in javascript into a variable

How can you run a getelementbyid on an Array and a String in Javascript and set it as a variable that is not null for example foo["dog"] x = getelementbyid(foo[0]+"food") and now x = dogfood
<script>
var myrows = new Array();
$(function() {
$("#check").click(function(){
myrows=[]
$(".head input:checked").not("#selectall").each(function(){
myrows.push($(this).parent().attr("id"));
}).value;
alert(myrows);
});
$("#subbut").click(function(){
var x;
var r=confirm("Are you sure you?");
if (r==true){
x="You pressed OK!";
}else{
Object.cancel;
}
**alert( myrows[0]+"servername" + " before" );
for(var i =0; i< myrows.length; i++){
alert(myrows[i] +"rootname" +" in loop" );
var j= document.getElementById(xmyrows[i] +"rootname" );
alert(j+" after call" );
var y = document.getElementById(myrows[i]+"servername");
document.getElementById("id_rootname").value= j.textContent;
document.getElementById("id_servername").value= y.textContent ;**
$.post($("#forms").attr("action"), $("#forms").serialize(), function(data) {
});
}
});
});
</script>

I don't really understand what the array/string problem is, but from the comments it seems you're looking for a way to do dynamic form submission: Dan Davis has provided the nuts and bolts of the solution in his comment — for each form you need to submit dynamically (without a refresh), create an iframe, then set the respective form's target attribute to that iframe's ID:
<form id="form1" target="#form1Response">
...
</form>
<form id="form2" target="#form2Response">
...
</form>
<iframe id="#form1Response"></iframe>
<iframe id="#form2Response"></iframe>
You will then need to attach your server response callbacks to the various iframes' load events. Beware though: even an empty iframe fires a load event, so you will need to filter false positives (empty iframe contents) in your callback.
Another caveat: if your server responds with JSON, IE will prompt the user to save the response to the filesystem before your script can intercept — so make sure the MIME type heading is set to text/plain or text/html to make sure the response is loaded into the iframe's DOM.

This can happen because java script allows white spaces sometimes if a string is concatenated with a number. try removing the spaces and create a string and then pass it into getElementById.
example:
var str = myrows[i]+"rootname";
str = str.replace(/^\s+|\s+$/g,"");
var str1 = myrows[i]+"servername";
str1 = str1.replace(/^\s+|\s+$/g,"");
var j= document.getElementById(str);
var y = document.getElementById(str1);
document.getElementById("id_rootname").value= j.textContent;
document.getElementById("id_servername").value= y.textContent ;
}