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POHow to auto-update selected item in dropdown to all the connected clients in SignalR with Knockout.js?
 

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  1. POHow to auto-update selected item in dropdown to all the connected clients in SignalR with Knockout.js?
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    <p><strong>SOLVED</strong>:</p> <p>Added the new corrected lines of code and commented the old ones.</p> <hr/> <p>For a <strong>real-time</strong> application using <strong>SignalR</strong>, i want changes made by a user to be visible in real-time by all the connected clients. </p> <p>It's <strong>ok</strong> with a simple <strong>textbox</strong>, but when i use a <strong>dropdown list</strong>: when a user select an item, i want the selected item from dropdown to be <strong>automatically set (auto-updated)</strong> to all connected clients.</p> <p><strong>Knockout.js</strong> seems to be the obvious choice, but i think i have a problem on subscribe... or elsewhere?</p> <p>What i have:</p> <p>(<strong>ASP .NET Razor</strong>) <strong>Dropdown</strong>:</p> <pre><code>//@Html.DropDownListFor(model =&gt; model.UserProfile.UserId, (SelectList)ViewBag.DDLUsersId, "Select User", new { @class = "ui-corner-all", @data_bind="value: selectedResponsible_UserId" }) @Html.DropDownListFor(model =&gt; model.UserProfile.UserId, (SelectList)ViewBag.DDLUsersId, "Select User", new { @class = "ui-corner-all", @data_bind="value: Responsible_UserId" }) </code></pre> <p>(<strong>HTML</strong>) which generates:</p> <pre><code>//&lt;select class="ui-corner-all" data-bind="value: selectedResponsible_UserId" id="UserProfile_UserId" name="UserProfile.UserId"&gt;&lt;option value=""&gt;Select User&lt;/option&gt; &lt;select class="ui-corner-all" data-bind="value: Responsible_UserId" id="UserProfile_UserId" name="UserProfile.UserId"&gt;&lt;option value=""&gt;Select User&lt;/option&gt; &lt;option value="1"&gt;test1&lt;/option&gt; &lt;option value="2"&gt;test2&lt;/option&gt; &lt;/select&gt; </code></pre> <p>(<strong>JavaScript</strong>) <strong>ViewModel</strong>:</p> <pre><code>function taskViewModel(id, title, Responsible_UserId, ownerViewModel) { this.taskId = id; this.title = ko.observable(title); //this.selectedResponsible_UserId = ko.observable(Responsible_UserId); this.Responsible_UserId = ko.observable(Responsible_UserId); this.notification = function (b) { notify = b } var self = this; this.title.subscribe(function (newValue) { ownerViewModel.updateTask(ko.toJS(self)); }); //this.selectedResponsible_UserId.subscribe(function (newValue) this.Responsible_UserId.subscribe(function (newValue) { ownerViewModel.updateTask(ko.toJS(self)); }); } </code></pre> <p>(<strong>JavaScript</strong>) <strong>Function</strong> from <strong>Client-Side</strong> which call the function from <strong>Server-Side</strong> with specified object:</p> <pre><code>this.updateTask = function (task) { if (notify) this.hub.server.s_Update(task); } </code></pre> <p>(<strong>C#</strong>) <strong>Function</strong> from <strong>Server-Side</strong> which modify values in <strong>DB</strong> and call the function from <strong>Client-Side</strong> for all the connected <strong>Clients</strong> with specified object:</p> <pre><code>public bool S_Update(Task updatedTask) { using (var context = new ToDoDbContext()) { var oldTask = context.Tasks.FirstOrDefault(t =&gt; t.taskId == updatedTask.taskId); if (oldTask == null) return false; else { oldTask.title = updatedTask.title; //??? Here, value 'updatedTask.Responsible_UserId' was NULL !!! oldTask.Responsible_UserId = updatedTask.Responsible_UserId; context.SaveChanges(); Clients.All.C_TaskUpdated(oldTask); return true; } } } </code></pre> <p>(<strong>JavaScript</strong>) <strong>Function</strong> from <strong>Client-Side</strong> which should <strong>update</strong> the <strong>Interface</strong>:</p> <pre><code>this.hub.client.C_TaskUpdated = function (t) { var task = ko.utils.arrayFilter(tasks(), function (value) { return value.taskId == t.taskId; })[0]; notify = false; task.title(t.title); //!! obvious, here was set to NULL. //task.selectedResponsible_UserId(t.Responsible_UserId); task.Responsible_UserId(t.Responsible_UserId); notify = true; }; </code></pre>
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    1. USFlorin Vîrdol
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    1. COPlease, whoever down-voted this question, i ask to justify his/her action, to improve it!! Thanks.
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      1. POHow to auto-update selected item in dropdown to all the connected clients in SignalR with Knockout.js?
      1. USFlorin Vîrdol
    2. COIf I follow this correctly, is your prop called `selectedResponsible_UserId` on the client-side and `Responsible_UserId` on the server. I don't see anywhere that maps it to something different.
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      1. USRP Niemeyer
    3. CO@RPNiemeyer Thanks, you were right! I changed the property name from Client-Side (`selectedResponsible_UserId` to `Responsible_UserId`) and everything worked like a charm!
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