If I have a Controller, with an Index page:
#model IEnumerable<MvcMovie.Models.Movie>
#{
ViewBag.Title = "Index";
}
<h2>Index</h2>
<table>
<tr>
<th>
Title
</th>
....
</tr>
#foreach (var item in Model) {
<tr>
<td>
#Html.DisplayFor(modelItem => item.Title)
</td>
....
</tr>
}
</table>
Whats the advantage of using #model IEnumerable<Movie>? Why couldn't I just define ViewBag.Movies in the Controller and use that in the index page?
The advantage of using #model IEnumerable<Movie> is the clarity of saying right upfront - this view is meant to display (an) IEnumerable<Movie>. It may use some additional information (which will be stored in the ViewBag), but IEnumerable<Movie> is what it's meant to display. That's conceptually the reason, which has a lot to do with the concept of the MVC design pattern. And of course there are the technical reasons as #Tridus said.
Strictly speaking, you could. But you're not going to get the benefit of Intellisense or a straightforward "this is the wrong type" error if you pass in something else to the View. You also won't get errors caught if you enable compiling your views at compile time (though that's off by default so it's less of a benefit).
Related
I know this sound somewhat off-piste but how would you create a weakly typed view where you pass in a collection of objects and iterate in razor accordingly and display in a table?
-- Controller View --
???
-- Razor View ---
#foreach (var item in Model)
{
<tr>
<td>
#item.attr1
</td>
<td>
#item.attr2
</td>
</tr>
}
Frist you know the data send
From Controller -------> view by two way
By weak type view
and by strong type view
there is no other way of passing data from controller to view ...(remember)
what is intelliscence ----> which show the related sub property of any model
like we write Model. --------> then all property show in
droupdown list after dot(.).
A.what is weak type view
This is used without using model i.e like using ViewBag and other.
There is no intellisence for this type of view and it is complicated, and when you write
any name which not exist then it give at runtime error.
Ex.
.............Controller
ViewBag.List = List<job>;
return View();
.............Razor View
#foreach(var item in ViewBag.List)
{
// when you write no intellisence and you want to write your own correct one...
#item.
}
B. What strongly type view
this is used model to send data from controller to view an vice-versa.
Model are strongly typed to view so, it show intellicence and when you write wrong
then there only error show at compile time..
Ex.
.................Controller
List<job> jobdata =new List<job>();
return View(jobdata);
................view
//Mention here datatype that you want to strongly type using **#model**
#model List<job>
#foreach(var item in Model)
//this **Model** represent the model that passed from controller
// default you not change
{
#item. //then intellisence is come and no need write own ....
}
that is weak and strong type view ......
So now you solve any problem with this basic.....
may I hope it help u....
But it is best to use Strongly Typed view so it become easy
to use and best compare to weak...
#model dynamic
Will do what you want, I believe.
If its going to be a collection, then maybe use
#model ICollection
It's not weakly typed. It's typed to a collection of some kind.
#model IEnumerable<MyClass>
OK, late to the party I know, but what you're after is a view stating "#model dynamic" as already stated.
Working Example: (in mvc3 at time of posting)
NB In my case below, the view is actually being passed a System.Collections.IEnumerable
As it's weakly typed, you will not get intelesense for the items such as #item.Category etc..
#model dynamic
#using (Html.BeginForm())
{
<table class="tableRowHover">
<thead>
<tr>
<th>Row</th>
<th>Category</th>
<th>Description</th>
<th>Sales Price</th>
</tr>
</thead>
#{int counter = 1;}
#foreach (var item in Model)
{
<tbody>
<tr>
<td>
#Html.Raw(counter.ToString())
</td>
<td>
#item.Category
</td>
<td>
#item.Description
</td>
<td>
#item.Price
</td>
</tr>
#{ counter = counter +1;}
</tbody>
}
</table>
}
Edit: removed some css
I've got a model that is returning a IEnumerable of football picks for a variable number of users. Due to this, I'm dynamically building an html table with a variable number of columns. Basically, my picks will come back like this. However, each game is going to be repeated for each User, so I'm only adding the first 3 columns of each table row once, and then adding only a single tag until the gameID changes. I know there are probably better ways to do this, but it's just a side project that I need to get done quickly. And, I just want to figure out why it's not working.
GameID
GameDateTimeDisplay
GameTeamDisplay
WinningTeamDisplay
PickedTeamAbbr
OK, so here is the insanity that doesn't work. I can get my table headers created successfully, but then the tbody isn't working, but it's erroring in an odd place.
I had to put all the #Html.Raw(...) stuff in there because it was having trouble finding the end tags for the foreach and if statements without them.
Anyway, here is my code. The line that is causing the exception is this:
#gameID = #pick.Game.GameID;
The exception is --> Compiler Error Message: CS1525: Invalid expression term '='
The intellisense shows #gameID as a variable and the #pick.Game.GameID seems to be correct as well.
<table>
<thead>
<tr>
<th>Game</th>
<th>Game Date/Time</th>
<th>Winner</th>
#foreach(var name in #Model.UserNames) {
<th>#name</th>
}
</tr>
</thead>
<tbody>
#{
int lastGameID = 0;
int gameID = 0;
bool firstGame = true;
}
#foreach(var pick in #Model.Picks) {
#gameID = #pick.Game.GameID;
if(#gameID != #lastGameID) {
if(!#firstGame){
<text>#Html.Raw("</tr>")</text>
}
#Html.Raw(
<tr>
<td>#pick.GameTeamDisplay</td>
<td>#pick.GameDateTimeDisplay</td>
<td>#pick.Game.WinningTeam.TeamAbbr</td>
<td>#pick.PickedTeamAbbr</td>
)
}
else {
#Html.Raw(<td>#pick.PickedTeamAbbr</td>)
}
}
#Html.Raw(</tr>)
</tbody>
</table>
UPDATE:
I've removed the #Html.Raw, , etc... Also wrapped the gameID assignment in a #{}. It's now giving me an error on this line,
#{gameID = #pick.Game.GameID;}
Compilation Error: CS1501: No overload for method 'Write' takes 0 arguments
Here is the updated Code:
#foreach(var pick in #Model.Picks) {
#{gameID = #pick.Game.GameID;}
if(#gameID != #lastGameID) {
if(!#firstGame){
#:</tr>
}
#:<tr>
<td>#pick.GameTeamDisplay</td>
<td>#pick.GameDateTimeDisplay</td>
<td>#pick.Game.WinningTeam.TeamAbbr</td>
<td>#pick.PickedTeamAbbr</td>
}
else {
<td>#pick.PickedTeamAbbr</td>
}
}
</tr>
You need to surround it with { } to make it a codeblock
#{gameID = pick.Game.GameID;}
Also, you don't need the # inside the foreach/if statements because they're code blocks.
e.g. you could just write:
foreach(var name in Model.UserNames) {
Just write
#foreach(var pick in Model.Picks) {
<tr>
<td>#pick.GameTeamDisplay</td>
<td>#pick.GameDateTimeDisplay</td>
<td>#pick.Game.WinningTeam.TeamAbbr</td>
<td>#pick.PickedTeamAbbr</td>
</tr>
}
You don't need # inside code block. You can use #: instead of <text>, Html.Raw
You can see here Razor syntax reference
I determined that my Razor view code was simply too complex. The real problem was that I was trying to force a view to work with a Model that I had created for another view. I ended up creating a few more models specifically for this view. Code is much cleaner and best of all it works! Here is the code I ended up with.
<table>
<thead>
<tr>
<th>Game</th>
<th>Game Date/Time</th>
<th>Winner</th>
#foreach(var name in #Model.UserNames) {
<th>#name</th>
}
</tr>
</thead>
<tbody>
#foreach(var game in #Model.Games) {
<tr>
<td>#game.GameDescription</td>
<td>#game.GameDisplayDateTime</td>
<td>#game.GameWinner</td>
#foreach(var pick in game.GamePicks){
<td>#pick.PlayerPick</td>
}
</tr>
}
</tbody>
</table>
I know that I can set the SelectedItem in my controller, but I can't figure out how to set it in my view. I'm working on a sort of flashcard (study guide) application and I have imported about 400 test questions. Now I want to write a page for the instructor to be able to select a "Category" for each question. I'd like them to be able to update the category for all the questions on one page. My model has a question entity that contains a foreign key field to the category entity (the field is called QuestionCategory). So, my view is based on the Question entity, but I'm sending over the list of Categories (there are 14) in the ViewBag (so I don't have to send a full SelectList over with each of the 400 questions. As my view is iterating thru the items in my View, I just want to add a SelectList that contains the 14 categories in my ViewBag and then set the SelectedItem based on the value of item.QuestionCategory. I can't make it work.
Here's my controller action:
public ActionResult Index()
{
var context = new HBModel.HBEntities();
var query = from q in context.tblQuestions.Include("tblCategory") select q;
var questions = query.ToList();
ViewBag.Categories = new SelectList(context.tblCategories, "CategoryID", "CategoryName");
return View(questions);
}
Here's some of the things I've tried in the view (with associated error messages in the comments)
#model IEnumerable<HBModel.tblQuestion>
#{
ViewBag.Title = "Index";
Layout = "~/Views/Shared/_Layout.cshtml";
}
<h2>Index</h2>
<p>
#Html.ActionLink("Create New", "Create")
</p>
<table>
<tr>
<th>
Question
</th>
<th>
Answer
</th>
<th>
AnswerSource
</th>
<th>
Category
</th>
<th>
Action
</th>
</tr>
#foreach (var item in Model) {
<tr>
<td>
#item.Question
</td>
<td>
#item.Answer
</td>
<td>
#item.AnswerSource
</td>
<td>
#item.tblCategory.CategoryName
#*This one works, but cannot initialize the selected item to be current database value*#
#Html.DropDownList("Categories")
#*compile error - CS0200: Property or indexer 'System.Web.Mvc.SelectList.SelectedValue' cannot be assigned to -- it is read only*#
#*#Html.DropDownListFor(m => item.QuestionCategory, (ViewBag.Categories as SelectList).SelectedValue = item.QuestionCategory)*#
#*error {"DataBinding: 'System.Web.Mvc.SelectListItem' does not contain a property with the name 'CategoryId'."}*#
#Html.DropDownListFor(m => item.QuestionCategory, new SelectList(ViewBag.Categories, "CategoryId", "CategoryName"))
#*error - {"DataBinding: 'System.Char' does not contain a property with the name 'CategoryId'."}*#
#Html.DropDownListFor(m => item.QuestionCategory, new SelectList("Categories", "CategoryId", "CategoryName"))
)
</td>
<td style="width: 100px">
#Html.ActionLink("Edit", "Edit", new { id = item.QuestionID }) |
#Html.ActionLink("Delete", "Delete", new { id = item.QuestionID })
</td>
</tr>
}
</table>
Of course, if I can get this to work, I'll need to try and add an action to go back to the controller and update all the records, but I'll just be happy to resolve my current issue.
I would really appreciate any help on this - Thanks!
You need to explicitly create the options in the select tag, using #Html.DropDownList, as follows (taken from a working app):
#Html.DropDownListFor(model => model.IdAccountFrom, ((IEnumerable<FlatAdmin.Domain.Entities.Account>)ViewBag.AllAccounts).Select(option => new SelectListItem {
Text = (option == null ? "None" : option.AccountName),
Value = option.AccountId.ToString(),
Selected = (Model != null) && (option.AccountId == Model.IdAccountFrom)
}), "Choose...")
#Html.ValidationMessageFor(model => model.IdAccountFrom)
You obviously need to change to the properties on your #Model.
NOTE:
This code was auto-generated by the MvcScaffolding NuGet package when I scaffolded a controller.
This package requires you to use Entity Framework Code First POCO classes for your entities. These are easy to generate from an existing database using the Entity Framework Power Tools CTP.
With MVC, you need to spend some time researching the tooling that is out there to help you generate the stuff that you need. Using these tools is a great way to get started and to see how to do things. You can then tweak the output to your heart's content.
I have a four viewmodels/views which display similar but different data.
Is it possible to have a property on the viewmodel which retuns ActionLinks (or the html for them ?)
e.g.
At the moment on each of my Views I have
<table>
<tr>
<td>#Html.ActionLink("My Open Calls", "MyOpenCalls")</td>
<td>#Html.ActionLink("All Open Calls", "AllOpenCalls")</td>
<td>#Html.ActionLink("My Calls Today", "MyCallsToday")</td>
<td>#ViewBag.Title</td>
</tr>
</table>
but would it be possible to have:
<table>
<tr>
#Model.MenuHtml
</tr>
</table>
While it might be possible to store HTML in view models properties I don't think it would be a good idea. If you want to reuse some code why not simply put this table into a partial and then include the partial:
#Html.Partial("_Links")
Another possibility is to use a custom HTML helper that will generate those links.
I'm new to MVC and I have a question concerning my view.
I have a strongly typed view:
#model CellularAutomata.Models.D1CellularAutomata
#{
ViewBag.Title = "View";
}
<h2>View</h2>
<table>
#foreach (CellularAutomata.Models.Grid grid in Model.GridHistory){
<tr>
#foreach (CellularAutomata.Models.Cell cell in grid.Cells[0]){
if (cell.State == CellularAutomata.Models.State.On){
<td>X</td>
}
if (cell.State == CellularAutomata.Models.State.Off){
<td>O</td>
}
}
</tr>
}
</table>
Does it break the rules of MVC to reference parts of the model in my view, such as
(CellularAutomata.Models.Cell cell in grid.Cells[0])
or
(cell.State == CellularAutomata.Models.State.On)
If this is incorrect, what is the best way to go about fixing it?
Not at all, since your view is strongly typed against your model. If your view was model agnostic then it would be a problem, but as this is a view for D1CellularAutomata it is appropriate to have D1CellularAutomata specific references in your view.