I am new to MVC, and have a MVC 4 web application and I retrieve a collection of items in the application start(static reference data). I want to display this collection of items when my view loads and loop through it creating links on view, I want to use javascript to inject this information. I found a post where they mention doing it in the view like this
<script type="text/javascript>
<%= Model.JavascriptToInsert %>
</script>
but I am looking for a working example of implementing this approach. Any guidance would be appreciated.
You should serialize your collection to json before you put it to your page.
Use ViewBag to show the data
Controller:
//Show data with ViewBag
public ActionResult Index()
{
ViewBag.DataList = SomeClass.SomeStaticList;
return View();
}
View:
<script type="text/javascript">
var list = <%=Json.Encode(ViewBag.DataList)%>;
for (var i = 0; i < list.length; i++) {
//do something with your data
}
</script>
Use strongly-typed view
Controller:
//Show data with ViewModel
public ActionResult Index()
{
var model = new TempProject.Models.SampleModel();
model.ListData = SomeClass.SomeStaticList;
return View(model);
}
View:
<%# Page Language="C#" Inherits="System.Web.Mvc.ViewPage<TempProject.Models.SampleModel>" %>
<script type="text/javascript">
var list = <%=Json.Encode(Model.ListData) %>;
for (var i = 0; i < list.length; i++) {
//do something with your data
}
</script>
Related
I'm loading some of data to a list called "TransactionNames" in the code behind of the master page (TestMaster.Master).
Now I need to pass that list of data to front-end of the master page(TestMaster.Master) using java script.
I tried like above,
If you have a List in code behind that is declared outside a method:
public List<string> TransactionNames = new List<string>();
Then you need to create an array in javascript:
<script type="text/javascript">
var TransactionNames = ["<%= string.Join("\",\"", TransactionNames) %>"];
//or
var TransactionNames = <%= "['" + string.Join("','", TransactionNames) + "']" %>;
for (var i = 0; i < TransactionNames.length; i++) {
alert(TransactionNames[i]);
}
</script>
Or it becomes even easier when you use Newtonsoft.Json to serialize objects:
var TransactionNames = <%= Newtonsoft.Json.JsonConvert.SerializeObject(TransactionNames) %>;
You didn't mention exactly what do you want to do with the transaction names on the front-end of master page e.g. adding them to a menu, concatenating them to a label etc or creating a structure from the names;
Suppose you want to create a structure; here is the code
for(i =0;i< TransactionNames.length;i++)
{
$("#ul").append("<li>" + TransactionNames[i] + "</li>");
}
You can do using declare global public variable:
Code Behind:
public string[] TransactionNames=new string[]
{
"schnauzer",
"shih tzu",
"shar pei",
"russian spaniel"
};
Source File:
<script type="text/javascript">
var TransactionNames= <%= TransactionNames %>;
for(var i=0; i < TransactionNames.length;i++){
var tx=TransactionNames[i];
}
</script>
I have a script in my header that is calling a web api which should populate a view model. This is below.
#using GigHub.Controllers
#using GigHub.ViewModel
#model GigHub.ViewModel.ProjectsViewModel
#{
ViewBag.Title = "Projects";
}
<head>
<script>
(function getProjects() {
$.get("/api/projects")
.done(function () {
alert("Got Projects");
})
.fail(function () {
alert("Something failed!");
});
});
</script>
</head>
I then have my html that would loop through the viewModel and set it up throughout the html, but every time it gets run, it is throwing a null reference exception to Model.ProjectList in the for each because it hasn't populated yet. I thought putting the script in the header would let it run first, but that doesn't seem to be the case.
<h2>Projects</h2>
<ul class="gigs voffset4" style="width: 600px;">
#foreach (var project in Model.ProjectList)
{
<li>
<div class="date">
<div class="month">
#project.Name
</div>
<div class="day">
#project.Key
</div>
</div>
<div class="details">
<span class="artist">
#project.Id
</span>
<span class="genre">
#project.ProjectTypeKey
</span>
</div>
</li>
}
</ul>
Here is my actual projectsController
public class ProjectsController : Controller
{
private readonly string m_Username = Properties.Settings.Default.username;
private readonly string m_Password = Properties.Settings.Default.password;
public ActionResult Index()
{
var client = new RestClient("https://example.net/rest/api/2/");
client.Authenticator = new HttpBasicAuthenticator(m_Username, m_Password);
var request = new RestRequest("project/", Method.GET);
request.RequestFormat = DataFormat.Json;
request.OnBeforeDeserialization = resp => { resp.ContentType = "application/json"; };
var response = client.Execute<List<Project>>(request);
var content = response.Content; // raw content as string
if (content == null)
throw new Exception(response.ErrorMessage);
var projectArray = JsonConvert.DeserializeObject<List<Project>>(response.Content);
var viewModel = new ProjectsViewModel()
{
ProjectList = projectArray,
Heading = "Projects"
};
return View("Projects", viewModel);
}
}
You are trying to mix javascript and C# code together and expecting it to work! No. It does not work that way.
The c# code in your view ( the foreach block) gets executed by razor in the server and the resulted html markup will be send to the client browser. That means, if you are accessing Model.ProjectList in your view, you should make sure that you are passing a model to your view with that property(ProjectList).
You have 2 options.
1. Full server side approach
In your get action, create an object of your view model, set the ProjectList property and send it to view.
public ActionResult Index()
{
var vm = new YourViewModel();
vm.ProjectList= GetListOfProjectsFromSomeWhere();
return View(vm);
}
private List<ProjectItem> GetListOfProjectsFromSomeWhere()
{
var list=new List<ProjectItem>();
list.Add(new ProjectItem { Name="Project 1"}); // Replace with real data here
return list;
}
Assuming you have a view model called YourViewModel as below
public class ProjectItem
{
public string Name {set;get;}
}
public class YourViewModel
{
public List<ProjectItem> ProjectList {set;get;}
}
and
and make sure your razor view is strongly typed to this view model
#model YourViewModel
<h2>Projects</h2>
#foreach (var project in Model.ProjectList)
{
<p>#project.Name</p>
}
2. Use ajax to load page content.
From your client side code,make the call to your api(like you did) and parse the response and update the DOM.
You need to create a container element in your view so that your javascript code can append items to that from the api call result.
<ul id="projects"></ul>
Now make sure that your javscript code will execute on the document ready event.
function getProjects() {
$.get("/api/projects")
.done(function (data) {
var projectHtml="";
$.each(data,function(i,item){
projectHtml+="<li>"+item.Name+"-"+item.Key+"</li>";
});
$("#projects").html(projectHtml);
})
.fail(function () {
alert("Something failed!");
});
}
$(function(){
getProjects();
});
Assuming your api call returns an array of item, each with a Name & Key property like this
[{Name:"Project1", Key:"Pr1"},{Name:"Project2", Key:"Pr2"}]
I don't know how to use razor syntax in Javascript.
I want to make Html.ListBoxFor with items from my model. I used to use:
#Html.ListBoxFor(x => x.TagIdList, (MultiSelectList)ViewBag.Tags, new { #class = "chzn-select", data_placeholder = "Tags..." })
As you see I want also use chzn-select class, to have better layout.
For now, I just have this code above in HTML as plain text, but I want have there things from my model.
Any ideas?
There is my code in ASP.NET MVC:
#model Generator.Models.ExamModel
#{
ViewBag.Title = "Generate";
}
#section Scripts {
#Scripts.Render("~/bundles/jqueryval")
<script src="#Url.Content("~/Multiple_chosen/chosen.jquery.js")" type="text/javascript"></script>
<script src="#Url.Content("~/Scripts/ListOfTags.js")" type="text/javascript"></script>
<script >
$(".chzn-select").chosen();
</script>
}
<link href="#Url.Content("~/Multiple_chosen/chosen.css")" rel="stylesheet" type="text/css" />
<h1>#ViewBag.Title</h1>
<h2>#ViewBag.Message</h2>
#using (Html.BeginForm())
{
#Html.AntiForgeryToken()
#Html.ValidationSummary(true)
<fieldset>
<legend>Generate</legend>
<div class="editor-label">Numbers</div>
<div class="editor-field" id="NumberOfModels">
#Html.EditorFor(model => model.NumberOfQuestions)
</div>
<div class="editor-label">Tags</div>
<div id="itemsmodel"></div>
<br>
<p>
<input type="submit" value="Save" />
</p>
</fieldset>
}
And there is javascript file:
var models = document.getElementById("NumberOfQuestions");
var modelsTable = document.getElementById("itemsmodel");
models.addEventListener("change", drawModels, false);
function drawModels() {
var modelsNum = parseInt(models.value);
var curModels = modelsTable.childElementCount;
if (modelsNum > curModels) {
var delta = modelsNum - curModels;
for (var i = 0; i < delta; i++) {
var input = document.createElement("div");
input.className = "editor-field";
input.innerHTML = "#Html.ListBoxFor(x => x.TagIdList, (MultiSelectList)ViewBag.Tags, new { #class = \"chzn-select\", data_placeholder = \"Tags...\" })";
modelsTable.appendChild(input);
}
} else {
while (modelsTable.childElementCount > modelsNum) {
modelsTable.removeChild(modelsTable.lastChild);
}
}
}
drawModels();
My ViewModel: ExamModel.cs:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
namespace ExamGenerator.Models
{
public class ExaminationModel
{
public int Id { get; set; }
public string Name { get; set; }
public List<int> TagIdList { get; set; }
public int NumberOfQuestions { get; set; }
public string Content { get; set; }
}
}
My ActionResult Generate() in controller:
public ActionResult Generate()
{
ViewBag.Tags = new MultiSelectList(genKolEnt.TAGS, "Id", "Name", null);
return View();
}
While you can generate HTML in Javascript using Razor, if the Javascript is in an MVC view, I find that injecting into JS leads to maintenance problems. You ideally want all your JS in separate files to allow for bundling/caching and the ability to break-point the JS code (which is harder in the view).
Either inject only simple things into JS on the page, or inject elements instead.
You can inject your template Razor list into a dummy script block, so you can extract the html from it later. The type="text/template" means the browser will ignore it e.g.:
<script id="ListTemplate" type="text/template">
#Html.ListBoxFor(x => x.TagIdList, (MultiSelectList)ViewBag.Tags, new { #class = "chzn-select", data_placeholder = "Tags..." })
</script>
The view page now looks like this (left out the irrelevant parts):
#section styles{
<link href="#Url.Content("~/Multiple_chosen/chosen.css")" rel="stylesheet" type="text/css" />
}
<h1>#ViewBag.Title</h1>
<h2>#ViewBag.Message</h2>
<script id="ListTemplate" type="text/template">
#Html.ListBoxFor(x => x.TagIdList, (MultiSelectList)ViewBag.Tags, new { #class = "chzn-select", data_placeholder = "Tags..." })
</script>
#using (Html.BeginForm())
{
#Html.AntiForgeryToken()
#Html.ValidationSummary(true)
<fieldset>
<legend>Generate</legend>
<div class="editor-label">Numbers</div>
<div class="editor-field" id="NumberOfModels">
#Html.EditorFor(model => model.NumberOfQuestions)
</div>
<div class="editor-label">Tags</div>
<div id="itemsmodel"></div>
<br>
<p>
<input type="submit" value="Save" />
</p>
</fieldset>
}
Script now looks like this (jQuery version with JS as comments):
// ListOfTags.js file
// This is a shortcut DOM ready handler for $(document).ready(function(){ YOUR CODE HERE })
$(function () {
// Attach an event handler for the "change" event
$('#NumberOfQuestions').change(function () {
var $numberOfQuestions = $(this); // Convert current DOM element (the counter) to a jQuery element
var $modelsTable = $('#itemsmodel'); // document.getElementById("itemsmodel");
var modelsNum = ~~$numberOfQuestions.val(); // parseInt(models.value);
var curModels = $modelsTable.children().length; // modelsTable.childElementCount
var delta = modelsNum - curModels;
// While too few, add more
while (delta > 0) {
var $input = $('<div>').addClass('editor-field'); // document.createElement("div"); .className = "editor-field";
var template = $('#ListTemplate').html(); // Fetch the template from a script block (id="ListTemplate")
$input.html(template); // input.innerHTML =
$modelsTable.append($input); // modelsTable.appendChild(input);
delta--;
}
// While too many, remove the last
while (delta++ < 0) {
$modelsTable.children().last().remove(); // modelsTable.removeChild(modelsTable.lastChild);
}
}).change(); // Trigger an initial change event so it runs immediately
});
Notes/tips:
Place any JS in the page, at the bottom of the view, as it is easier to find. It does not matter where the #section Scripts is as the master page determines where it is injected on the final page.
Always use single quotes (') in Javascript constants by default, so that nested strings can be " which are more often required than 's. Just a good habit to get into. In fact if you had used them your code may have worked as you have added \ escaping to the quotes which will mess up the Razor processing
e.g.:
= '#Html.ListBoxFor(x => x.TagIdList, (MultiSelectList)ViewBag.Tags, new { #class = "chzn-select", data_placeholder = "Tags..." })';
If you add a #RenderSection("styles", required: false) to your master page(s) you can do the same thing for CSS as you do for scripts (ensuring all CSS is loaded in the header (for consistency). Just place them in a #section styles block.
e.g.
<head>
...
#Styles.Render("~/Content/css")
#RenderSection("styles", required: false)
...
</head>
~~ is a handy (and fast) alternative to parseInt to convert values to integers.
Use $ as a prefix for jQuery object variables. This makes it easier to remember when to use jQuery methods vs DOM properties.
Test controller code:
private MultiSelectList TagList()
{
var items = new List<KeyValuePair<int, string>>() {
new KeyValuePair<int, string>(1, "MVC"),
new KeyValuePair<int, string>(2, "jQuery"),
new KeyValuePair<int, string>(3, "JS"),
new KeyValuePair<int, string>(4, "C#"),
new KeyValuePair<int, string>(5, "PHP")
};
MultiSelectList list = new MultiSelectList(items, "key", "value", null);
return list;
}
// Get request starts with one list
public ActionResult Test()
{
ExamModel vm = new ExamModel()
{
NumberOfQuestions = 1,
TagIdList = new List<int>()
};
ViewBag.Tags = TagList();
return View(vm);
}
[HttpPost]
public ActionResult Test(ExamModel model)
{
ViewBag.Tags = TagList();
return View(model);
}
If it's a static JavaScript file and you are not generating it dynamically with razor view engine It won't work because in this case there is no processing performed on a server side. It is the same as accessing static html page/css file/image and etc...
On the other hand if this JavaScript is part of some Razor view, which means that it gets rendered by razor view engine, when you have return View() (or anything like that) in your controller action, than this code should work.
The problem is, java script files are not processed by server, so you won't be able to insert anything in those using ASP.NET MVC. Razor files on the other hand are processed on server so you can insert data into those (either through view bag or model).
One way is:
.cshtml:
<script>
var someVariable = '#model.data';
</script>
then use this variable in your javascript file:
function someFunction(){
var myData = window.someVariable;
}
The other way is to have all javascript in .cshtml file and render it as a partial view.
#Html.Partial("Path/to/javascript/in/razor/view")
edit: seeing your code, this will not help you very much.
If you want to dynamically add/remove dom elements, you will have to do it with javascript: either generate them with "document.createElement()" or load them via ajax if you want some server side processing.
#Html.ListBoxFor
is a server side helper that generates tag and fills it up depending on the parameters. You can do that with javascript as well.
I'm using MVC 4 and Entity Framework to develop an intranet web app. On one of my views, I have to implement the autocomplete feature. To do that, I'm using Bootstrap Typeahead. I tried to pass my action (so my function) to feed the input element but it seems that it doesn't work.
Here is my action result which returns an Json :
public ActionResult AutoComplete(string term)
{
var result = db.Persons.Where(p => p.FirstName.ToLower().Contains(term.ToLower()) || p.LastName.ToLower().Contains(term.ToLower())).ToList().Select(p => p.FullName).ToList();
return Json(result, JsonRequestBehavior.AllowGet);
}
My View and my script :
#model IEnumerable<BuSIMaterial.Models.Person>
#{
ViewBag.Title = "Index";
}
<link href="/Content/PagedList.css" rel="stylesheet" type="text/css" />
<h2>Index</h2>
<input type="text" class="typeahead" data-provide="typeahead">
#section Scripts
{
#Scripts.Render("~/bundles/jqueryval")
#Scripts.Render("~/bundles/jqueryui")
#Styles.Render("~/Content/themes/base/css")
$(".typeahead").typeahead({
source: function (query, process) {
var persons = [];
map = {};
// This is going to make an HTTP post request to the controller
return $.post('/Person/AutoComplete', { query: query }, function (data) {
// Loop through and push to the array
$.each(data, function (i, person) {
map[person.Name] = person;
map[person.F]
persons.push(country.Name);
});
// Process the details
process(countries);
});
},
updater: function (item) {
var selectedShortCode = map[item].ShortCode;
// Set the text to our selected id
$("#details").text("Selected : " + selectedShortCode);
return item;
}
});
</script>
}
In my master page, I call the Bootstrap jquery file(s). Any idea about what's going on?
Friends,
I am trying to use DyGraph in my application. Please look at the code below -
<head>
<meta http-equiv="X-UA-Compatible" content="IE=EmulateIE7; IE=EmulateIE9">
<title>crosshairs</title>
<script type="text/javascript" src="dygraph-combined.js"></script>
<script type="text/javascript" src="data.js"></script>
</head>
The code uses data.js file containing function to get some static data.
I want data.js to be generated using a controller method so that it will generate data using database.
Can anybody help me out to resolve this issue.
Thanks for sharing your valuable time.
You could define a controller action:
public ActionResult Data()
{
// Obviously this will be dynamically generated
var data = "alert('Hello World');";
return JavaScript(data);
}
and then:
<script type="text/javascript" src="<%= Url.Action("Data", "SomeController") %>"></script>
If you have some complex script that you don't want to generate in the controller you could follow the standard MVC pattern by defining a view model:
public class MyViewModel
{
... put required properties
}
a controller action which would populate this view model and pass it to the view:
public ActionResult Data()
{
MyViewModel model = ...
Response.ContentType = "application/javascript";
return PartialView(model);
}
and finally a view which in this case will be the javascript representation of the view model (~/Views/SomeController/Data.ascx):
<%# Control
Language="C#"
Inherits="System.Web.Mvc.ViewUserControl<MyViewModel>" %>
alert(<%= new JavaScriptSerializer().Serialize(Model.Name) %>);
Full Disclosure
This answer is copy/pasted from another question:
Dynamically generated Javascript, CSS in ASP.NET MVC
This answer is similar to other answers here.
This answer uses cshtml pages rather than ascx controls.
This answer offers a View-Only solution rather than a Controller-Only solution.
I don't think my answer is 'better' but I think it might be easier for some.
Dynamic CSS in a CSHTML File
I use CSS comments /* */ to comment out a new <style> tag and then I return; before the closing style tag:
/*<style type="text/css">/* */
CSS GOES HERE
#{return;}</style>
Dynamic JS in a CSHTML File
I use JavaScript comments // to comment out a new <script> tag and then I return; before the closing script tag:
//<script type="text/javascript">
JAVASCRIPT GOES HERE
#{return;}</script>
MyDynamicCss.cshtml
#{
var fieldList = new List<string>();
fieldList.Add("field1");
fieldList.Add("field2");
}
/*<style type="text/css">/* */
#foreach (var field in fieldList) {<text>
input[name="#field"]
, select[name="#field"]
{
background-color: #bbb;
color: #6f6f6f;
}
</text>}
#{return;}</style>
MyDynamicJavsScript.cshtml
#{
var fieldList = new List<string>();
fieldList.Add("field1");
fieldList.Add("field2");
fieldArray = string.Join(",", fieldList);
}
//<script type="text/javascript">
$(document).ready(function () {
var fieldList = "#Html.Raw(fieldArray)";
var fieldArray = fieldList.split(',');
var arrayLength = fieldArray.length;
var selector = '';
for (var i = 0; i < arrayLength; i++) {
var field = fieldArray[i];
selector += (selector == '' ? '' : ',')
+ 'input[name="' + field + '"]'
+ ',select[name="' + field + '"]';
}
$(selector).attr('disabled', 'disabled');
$(selector).addClass('disabled');
});
#{return;}</script>
No Controller Required (using Views/Shared)
I put both of my dynamic scripts into Views/Shared/ and I can easily embed them into any existing page (or in _Layout.cshtml) using the following code:
<style type="text/css">#Html.Partial("MyDynamicCss")</style>
<script type="text/javascript">#Html.Partial("MyDynamicJavaScript")</script>
Using a Controller (optional)
If you prefer you may create a controller e.g.
<link rel="stylesheet" type="text/css" href="#Url.Action("MyDynamicCss", "MyDynamicCode")">
<script type="text/javascript" src="#Url.Action("MyDynamicJavaScript", "MyDynamicCode")"></script>
Here's what the controller might look like
MyDynamicCodeController.cs (optional)
[HttpGet]
public ActionResult MyDynamicCss()
{
Response.ContentType = "text/css";
return View();
}
[HttpGet]
public ActionResult MyDynamicJavaScript()
{
Response.ContentType = "application/javascript";
return View();
}
Notes
The controller version is not tested. I just typed that off the top of my head.
After re-reading my answer, it occurs to me it might be just as easy to comment out the closing tags rather than use the cshtml #{return;}, but I haven't tried it. I imagine it's a matter of preference.
Concerning my entire answer, if you find any syntax errors or improvements please let me know.