How do I pass a class model object to my aspx page from code behind. In ASP MVC I can do it easily using a view model. Unfortunately I'm stuck
with a asp webforms application that requires some enhancements and I'm not to familar with asp.net webform and repeater controls.
protected void Page_Load(object sender, EventArgs e)
{
var orders = new List<Orders>();
// Do some stuff and get orders
var userInfo = new UserInfo()
{
Name = "Joe Blogs,
Age = "25",
Address = "123 Green Lane",
Orders = orders
};
}
I know I can create server variables and pass them individualy as follows but really I need to pass an object as it may containt an IEnumerable value that I need to iterate over in my aspx page. So I'm attempting at something like below:
<% foreach (var order in UserInfo.Orders) { %> <!-- loop through the list -->
<div>
<%= order %> <!-- write out the name of the site -->
</div>
<% } %>
Any help appreciated.
You can have a property, or a method, which return the object, and call it on the page. Make sure to use the right markup. In data bound context use:
<%# GetUser() %>
outside of that use
<%= GetUser() %>
Few considerations:
Make sure that the final output of expressions inside these tags is a string.
GetUser or however you call it cannot be private
In data binding context (e.g. inside gridview, repeater or such) this method will be called when the control is data bound
Outside of data binding context this code will be executed really early - don't rely on fetching data from DB on Page_Load, that is too late
However I would like to mention that you may want to reconsider the whole approach here. Plain foreach iteration inside aspx is usually a bad practice. Besides it will be difficult to get this markup right. Why do that when you can have a repeater bound to your data?
<asp:Repeater ID="Repeater1" ...>
<ItemTemplate>
<%# Eval("OrderName") %>
</ItemTemplate>
</asp:Repeater>
Repeater1.DataSource = userInfo.orders;
Repeater1.DataBind();
That would look much cleaner than any iteration inside aspx.
Related
I have a some pages that are slightly different, but all have the same "action buttons" that do the same tasks for each page. Instead of duplicating the code, I made a user control that includes buttons that perform actions - but there's one action I can't seem to do.
Each page has a textbox (that's not inside the user control, as it's in a different location of the page). When I click the "Save comment" button (that is within the User Control), I can't seem to access the text in the Textbox.
I have tried using something like this:
TextBox txtComments = (TextBox)this.Parent.FindControl("txtComments");
SaveChanges(txtComments.Text);
...but txtComments comes back as null.
So, I'm wondering if this is possible, or perhaps if there's a better way to do what I'm trying to do?
Edit: The Textbox is in a Placeholder on the original page...
Edit 2: Posting minified solution - still can't figure this one out.
Edit 3: Removed solution to conserve space - resolved the issue.
My solution ended up being surprisingly simple....
TextBox txt = this.Parent.Parent.FindControl("ContentPlaceHolder2").FindControl("TextBox1") as TextBox;
if (txt != null) Label1.Text = txt.Text;
Where I was going wrong before was that I was using the wrong ContentPlaceHolder ID. I was using the ID of the placeholder in the page, rather than the ID from the Master Page.
Use the Page property exposed by WebControl, the common base of server-side controls.
You could even then cast the instance to the specific page type and access the control directly (if scope allows), instead of using FindControl.
To recap the situation - you need to do a FindControl of a control on a page from a child control, however -
Your project has a MasterPage, in which case this.Page seems to not work, and we use this.Parent instead
Your "target" control is inside a PlaceHolder, which itself is inside a ContentPlaceHolder, so it's not as simple as just this.Parent.FindControl()
Your child ASCX control that is trying to find the "target" control, in this case a textbox, is actually in ANOTHER ContentPlaceHolder, so again, this.Parent.Parent or whatever will not work.
Since you mentioned after my initial this.Parent answer about the controls being in a different ContentPlaceHolder from each other, and in another child control, it complicates your query a bit.
Based on these criteria, and the fact that you at least know the contentPlaceHolder control which contains (somewhere inside of it) your target TextBox, here's some code I wrote that works for me in a new ASP.net Web Forms application:
It recursively checks controls collection of the ContentPlaceHolder you pass to it, and finds your control.
Just pass the ControlID and ContentPlaceHolderID, and it will recursively find it.
This code is a replacement for my original one below with the same project, located inside of ChildControl.ascx.cs file:
using System;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Linq;
using System.Collections.Generic;
namespace FindControlTest
{
public partial class ChildControl : System.Web.UI.UserControl
{
protected void Page_Load(object sender, EventArgs e)
{
var textBoxTest = FindControlInContentPlaceHolder("TextBoxTest", "FeaturedContent") as TextBox;
Response.Write(textBoxTest.Text);
Response.End();
}
private Control FindControlInContentPlaceHolder(string controlID, string contentPlaceHolderID)
{
if (null == this.Page ||
null == this.Page.Master)
{
return null;
}
var contentPlaceHolder = this.Page.Master.FindControl(contentPlaceHolderID);
var control = getChildControl(controlID, contentPlaceHolder);
return control;
}
private Control getChildControl(string controlID, Control currentControl)
{
if (currentControl.HasControls())
{
foreach(Control childControl in currentControl.Controls)
{
var foundControl = childControl.FindControl(controlID);
if (null != foundControl)
{
return foundControl;
}
else
{
return getChildControl(controlID, childControl);
}
}
}
return null;
}
}
}
Note:
I tried this in a few events and even on Init() I was able to get the TextBox value
If you are seeing a null it is likely due to an incorrect ID being passed or a situation I didn't encounter yet. If you edit your question with additional info (as there has been a lot of it) and show what variable is null, it can be resolved.
Note that I added some complexity to my MasterPage, such as a PlaceHolder inside a Panel, and then put the ContentPlaceHolder in there, and the code still works. I even compiled for .net 4.5, 4.0, 3.5, and 3.0 thinking maybe FindControl works differently with MasterPages, but still it works every time. You may need to post some additional MarkUp if you still get a null.
The Rest of the Test Project
The Page (based on default MasterPage)
<%# Page Title="Home Page" Language="C#" MasterPageFile="~/Site.Master" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="FindControlTest._Default" %>
<%# Register TagName="ChildControl" TagPrefix="uc1" Src="~/ChildControl.ascx" %>
<asp:Content runat="server" ContentPlaceHolderID="FeaturedContent">
<asp:PlaceHolder ID="PlaceHolderTest" runat="server">
<asp:TextBox ID="TextBoxTest" Text="Hello!" runat="server"/>
</asp:PlaceHolder>
</asp:Content>
<asp:Content ContentPlaceHolderID="MainContent" runat="server">
<uc1:ChildControl id="ChildControlTest" runat="server" />
</asp:Content>
I added a control called ChildControl.ascx that only has this in it:
<%# Control Language="C#" AutoEventWireup="true" CodeBehind="ChildControl.ascx.cs" Inherits="FindControlTest.ChildControl" %>
Hello child!
The result is "Hello!" on the page.
If you want to access the textbox property in codebehind as intellisence property, simply make it a string property in the user control.
1. In the user control, create a public string property that returns textbox string value..
public string MyText
{
get
{
return txt1.Text;
}
}
2. Register the user control on the page
<%# Register TagPrefix="uc" TagName="MyControl" Src="~/mycontrol.ascx" />
and declare it..
<uc:MyControl ID="control1" runat="server" />
3. From the codebehind now you can read the property..
Response.Write(control1.MyText);
Hope it helps
Thanks...
Want to create dynamic html layout without any asp controls. Actually I want to leave on aspx page only the first line
<%# Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="Kletka._Default" %>
and the generate full html layout on codebehind. Advise pls how to implement this.
One way is this:
protected void Page_Load(object sender, EventArgs e)
{
string coolHTML = #"<div class=""someclass"">... and other cool content</div>";
Response.Write(coolHTML);
}
With that said. This is a terrible idea. Constructing HTML dynamically on code behind is a nightmare to maintain, it doesn't perform as best as it can and you lose many other features that asp.net offers, which are the main reason to use ASP.NET in the first place.
What you can do is create User controls for specific things (footer, header, left panel, etc) and define a layout for them in markup; then on Code behind, you can add them to specific place holders in the page, depending on some business conditions.
Assuming you have a master page (or at least some content place holders in the page) as so:
<asp:ContentPlaceHolder id="footer" runat="Server" />
On code behind you can do:
footer.Controls.Add(new FooterControl());
Update OP just mentioned in the comments that he doesn't like asp.net controls...
You don't have to use ASP.NET controls, you can use regular HTML controls and set their runat="server" attribute if you need to be able to manipulate their properties on server-side. For example:
<div id="mydiv" runat="server" > some content </div>
On Code behind:
myDiv.Attributes.Add("class","css_class");
myDiv.Attributes.Add("onclick","callJavascriptFunction();");
// and so on.
It's okay to do this sort of thing occasionally under very specific circumstances but I'd avoid this sort of code because is difficult to maintain. Imagine you need to add another class to the myDiv element, for example. Now, you'd have to change you code as opposed to just changing your markup...
So...you want to use ASP.NET web forms without using the built in controls like GridView and so on, at all?
You can write your html and use protected properties?
<%= SomeWhereText %?
or to have the FULL html layout in the code behind make a property
protected string MyEntirePage {get;set;}
and build the string in the code behind
MyEntirePage="<h1>Hello</h1><p>body here</p><p>the end</p>";
and write it out in the aspx page via
<%=MyEntirePage%>
Re: "I've got your point, but I really don't like asp.net controls. I'd prefer to use html controls and customize them with js"
Install NancyFx or maybe the old (but still great) WCF Web Api and use something like KnockoutJs, jQuery or Backbone to perform ajax calls for the dynamic content = no asp.net web forms at all. Yay.
You would need to dynamically add the controls in the Page_Init event. So you need a container to hold your HTML, so you should start by adding a Panel to the Page, then the page's controls would get added to the Panel.
Panel pnl = new Panel();
Page.Controls.Add(pnl);
TextBox txt = new TextBox();
pnl.Controls.Add(txt);
etc....
I have a master page and all of my pages are inheriting it.
For formatting, I thought to place the content that differs from one page to another in a ContentPlaceHolder.
Now, how can I insert everything into that? Since I am planning to populate the ContentPlaceHolder with stuff from a database I suppose I will have to do it programmatically.
How can I add controls to ContentPlace Holder?
I checked other answers, but I cannot access it by its ID.
Should I use multiple ContentPlaceHolders from the beginning? Let's say I want to put movies. Should there be only one with all the images and descriptions and ratings, ore one ContentPlaceHolder for each thing?
I am opened to other solutions, as I have no experience with ASP.
Old question... but I just ran into this issue and this was the #1 post that kept coming up on Google, so figure I'd add my answer since the others didn't work in my case.
Here is how I did it when a regular <asp:Content wouldn't work (though in normal use, the answer #JayC is how you do it):
MasterPage has this ContentPlaceHolder:
<asp:ContentPlaceHolder ID="ScriptsPlace" runat="server"></asp:ContentPlaceHolder>
Had to dynamically add some JavaScript from a User Control. Trying to use the ContentPlaceHolder directly gives this error:
Parser Error Message: Content controls have to be top-level controls
in a content page or a nested master page that references a master
page.
So I wanted to add the script from the code-behind. Here is the Page Load for the .ascx file:
protected void Page_Load(object sender, EventArgs e)
{
ContentPlaceHolder c = Page.Master.FindControl("ScriptsPlace") as ContentPlaceHolder;
if (c != null)
{
LiteralControl l = new LiteralControl();
l.Text="<script type=\"text/javascript\">$(document).ready(function () {js stuff;});</script>";
c.Controls.Add(l);
}
}
UPDATE: So it turns out I had to use this in more places than I expected, and ended up using a way that was much more flexible / readable. In the user control itself, I just wrapped the javascript and anything else that needed to be moved with a regular div.
<div id="_jsDiv" runat="server">
$(document).ready(function() {
//js stuff
});
Other server controls or HTML junk
</div>
And then the code behind will find that div, and then move it into the ContentPlaceHolder.
protected void Page_Load(object sender, EventArgs e)
{
ContentPlaceHolder c = Page.Master.FindControl("ScriptsPlace") as ContentPlaceHolder;
HtmlGenericCOntrol jsDiv = this.FindControl("_jsDiv") as HtmlGenericControl;
if (c != null && jsDiv != null)
{
c.Controls.Add(jsDiv);
}
}
I actually put this code in a custom user control, and I just have my regular user controls inherit from the custom user control, so once I wrap the javascript/etc with a <div id="_jsDiv" runat="server">, the custom user control takes care of the rest and I don't have to do anything in the code behind of the user control.
What normally happens is
you set up your master pages with the proper html and ContentPlaceHolders
you create pages based off that master page. If you use Visual Studio, and tell it to create a new page based upon a existing Master page, it will add the Content areas for you.
you add things to the Content areas in the newly created page.
If you want to dynamically add controls to the master (or any) page, you could add controls to any existing control. If it shouldn't be wrapped in any way, just add a Placeholder (it is an asp.net control).
I did like this
<asp:Content ID="HeaderContent" runat="server" ContentPlaceHolderID="HeadContent">
<asp:Literal ID="jsstuff" runat="server"></asp:Literal>
</asp:Content>
And this went into code behind:
string stuff = #"<script type=""text/javascript"">
var searchBox = 0;
var currentCountry = '';
</script>";
jsstuff.Text = stuff;
If the namespace for content Page and Master page is not same then the content page control not accessible in Codebehind in content page.
Also, check your designer files. if the control not listed in designer file then delete the file and recreate (project->convert to web application)
Is there any way to directly access a field of class in the aspx page?
I have tried this:
In the aspx page I have added:
<form id="LoginForm" runat="server">
<asp:Label Text='<%# Eval("Test") %>' runat="server" ID="jym" />
</form>
and in the backend class of this page I have declared a property as:
private string test;
public string Test {
get {
return test;
}
set {
test = value;
}
}
This property is initialized in Page_Load() as: Test = "JYM";
But the problem is I am unable to see this value in the browser. The tag is rendered into <span/> but without any content.
What I am doing wrong?
Are you calling Page.DataBind() in Page_Load()?
You are using the # data binding operator in your embedded code block. The values that you bind to the control will only show after you have called DataBind() from either the control or the page (which will in turn call it for each control on the page).
If you only want to bind a value to that single label control you could just call jym.DataBind().
I would however suggest using a more descriptive name (id) for the Label control so it is clearer in the code about what is being databound.
See this page for more details.
UPDATE (extra info requested by OP in comment)
So you have 3 options:
1.
Call DataBind() as suggested above.
2.
Don't use a server side control for the label. Just use plain HTML and then you can use the following syntax:
<p><%= Test %></p>
3.
Set the value of the label in the code behind. For example in your page load you might have the following:
protected void Page_Load(object sender, EventArgs e)
{
jym.Text = Test;
}
You may want to use <%= this.Test%>. You can also do this.jym.Text=Test; in the Page Load evt.
I have a web user control, it serves some potentially intensive data calculations and I would like it to be output cached so that each page view doesn't recalculate the data. It resides on very frequently viewed pages so it's quite important I get it working right!
For context, it's used on our arcade:
http://www.scirra.com/arcade/action/93/8-bits-runner
Click on stats, the data for the graphs and stats are generated from this webusercontrol.
The start of the control is as follows:
public partial class Controls_Arcade_Data_ArcadeChartData : System.Web.UI.UserControl
{
public int GameID { get; set; }
public Arcade.ChartDataType.ChartType Type { get; set; }
protected void Page_Load(object sender, EventArgs e)
{
Now the difficulty I'm having is the output cache needs to be dependant on both the GamID and the ChartType.
This control is re-used with many different combinations of GameID's and Types, I need it to create a cache for each of these but am struggling to find out how to do this.
For example, one arcade game might pass in GameID = 93 and Type = GraphData, another might be GameID = 41 and Type = TotalPlaysData and another might be GameID = 93 but Type = TotalPlaysData. These should all return different data and have different output caches.
The control is used on the games page sort of like this (the parameters are actually set in the codebehind)
<div>Total Plays:</div>
<div class="count"><Scirra:ArcadeChartData runat="server" GameID="93" Type="TotalPlays" /></div>
<br /><br />
<div>Total Guest Plays:</div>
<div class="count"><Scirra:ArcadeChartData runat="server" GameID="93" Type="TotalGuestPlays" /></div>
etc.
Any help appreciated! I've spent a while looking online and it's kept coming up as something I need to solve but can't figure this one out.
Edit
Edit: I've tried adding this line to my control:
<%# OutputCache Duration="20" VaryByControl="GameID;Type" %>
But it just throws the error Object reference not set to an instance of an object. on the line where GameID is being set for the first time on the ASPX page using the control.
When a Control is retrieved from the output cache, it's not instantiated as an instance that you can manipulate; you just get the output the Control generated, not the Control itself. For example, you can't set properties on a cached Control from code behind, as you said in your question. The vary-by properties should be set declaratively (using an ExpressionBuilder might also work, though I haven't tried it).
To see in code behind whether a control has been retrieved from the output cache, check for null:
if (this.YourControlID != null) // true if not from cache
{
// do stuff
}
Even with that caveat, Control output caching is a bit quirky.
Try this:
<%# OutputCache Duration="20" VaryByControl="GameID;Type" Shared="true" %>
The output of the Control is stored in the output cache by associating it with a certain key. With Shared="true", the cache key is the value of all specified properties, together with the Control's ID. Without Shared="true", the cache key also includes the Page type, so the output would vary by Page -- which doesn't sound like what you want.
If you use the Control on more than one page, be sure to use the same ID on each page if you can, since the ID is included as part of the key for the output cache. If you can't or don't use different IDs, you will get a new copy of the Control's output in the cache for each unique ID. If the Controls with different IDs always have different property values anyway, that may not be an issue.
As an alternative to the OutputCache directive, you can set an attribute on the class declaration:
[PartialCaching(20, null, "GameID;Type", null, true)]
public partial class Controls_Arcade_Data_ArcadeChartData : UserControl
You need to take the following steps:
1) Add the following output cache directive to the page:
<%# OutputCache Duration="21600" VaryByParam="None" VaryByCustom="FullURL" %>
2) Add the following to global.asax:
public override string GetVaryByCustomString(HttpContext context, string arg)
{
if (arg.Equals("FullURL", StringComparison.InvariantCultureIgnoreCase)
{
// Retrieves the page
Page oPage = context.Handler as Page;
int gameId;
// If the GameID is not in the page, you can use the Controls
// collection of the page to find the specific usercontrol and
// extract the GameID from that.
// Otherwise, get the GameID from the page
// You could also cast above
gameId = (MyGamePage)oPage.GameID;
// Generate a unique cache string based on the GameID
return "GameID" + gameId.ToString();
}
else
{
return string.Empty;
}
}
You can get more information on the GetVaryByCustomString method from MSDN and also review some of the other caching options here.
create a cache object in the code
HttpRuntime.Cache.Insert("ArcadeChartData" + GameID + Type, <object to cache>, null, System.Web.Caching.Cache.NoAbsoluteExpiration,new TimeSpan(0, 0, secondsToCache),CacheItemPriority.Normal, null);
above cache item will be enough to your work, but if you really want to use output cache as well try following code in the code behind,
Response.AddCacheItemDependency("ArcadeChartData" + GameID + Type);
Response.Cache.SetExpires(DateTime.Now.AddSeconds(60));
Response.Cache.SetCacheability(HttpCacheability.Public);
Response.Cache.SetValidUntilExpires(true);
Setting values for the page output cache is the same as manipulating
the SetExpires and SetCacheability methods through the Cache property.
I know that my solution may look very simple and possibly weird but I tried it and it works.
You simply have to add this line in your UserControl.
<%# OutputCache Duration="10" VaryByParam="none" %>
Note : I have only tested the Framework 4.0. Also if ever you have to change the value of the property in the UserControl (MyInt, My String in this example) do it in the Page_Init event.
Here is all my code :
Page :
<%# Page Title="Home Page" Language="vb" MasterPageFile="~/Site.Master" AutoEventWireup="false" CodeBehind="Default.aspx.vb" Inherits="MyWebApp._Default" %>
<%# Register Src="~/UserControl/MyUserControl.ascx" TagPrefix="uc" TagName="MyUserControl" %>
<asp:Content ID="HeaderContent" runat="server" ContentPlaceHolderID="HeadContent">
</asp:Content>
<asp:Content ID="BodyContent" runat="server" ContentPlaceHolderID="MainContent">
<uc:MyUserControl ID="uc1" MyInt="1" MyString="Test" runat="server" />
<hr />
<uc:MyUserControl ID="uc2" MyInt="3" MyString="Test" runat="server" />
<hr />
<uc:MyUserControl ID="uc3" MyInt="1" MyString="Testing" runat="server" />
</asp:Content>
User Control:
<%# Control Language="vb" AutoEventWireup="false" CodeBehind="MyUserControl.ascx.vb" Inherits="MyWebApp.MyUserControl" %>
<%# OutputCache Duration="10" VaryByParam="none" %>
<div style="background-color:Red;">
Test<br />
<asp:Label ID="lblTime" ForeColor="White" runat="server" />
</div>
User Control Code:
Public Class MyUserControl
Inherits System.Web.UI.UserControl
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Debug.Write("Page_Load of {0}", Me.ID)
Dim oStrBldr As New StringBuilder()
For i As Integer = 1 To Me.MyInt
oStrBldr.AppendFormat("{0}: {1} - {2} at {3}<br />{4}", Me.ID, i, Me.MyString, Date.Now.ToLongTimeString(), System.Environment.NewLine)
Next
Me.lblTime.Text = oStrBldr.ToString()
End Sub
Public Property MyInt As Integer
Public Property MyString As String
End Class
Please keep me posted, I have other solutions if ever you wish but they are more complex. I may also post with C#
One easy trick is to put all the graphics in a new page receiving GameId and Type as querystring parameters, use the out-of-the-box output cache for querystring parameters and the put an iframe in your page. Also you can make use of the browser's cache and never get the server hit for a while.
Ok, well the reason why this so hard to make OutputCache work in this case is because it wasn’t design to be use with Property’s, however it works very well with QueryString parameters. So my next solution isn’t the most professional and probably not the best, but it is definitely the fastest and the one that requires less code changing.
Since it works best QueryString, I recommend you putting your UserControl in one blank page, and wend ever you want to use your UserControl make an iframe that links to your page with the UserControl with QueryString.
Where you want to use your UserControl:
<iframe src="/MyArcadeChartData.aspx?GameID=93&Type=TotalPlays"></iframe>
Full page markup, MyArcadeChartData.aspx
<%# Page ... %>
<%# OutputCache Duration="20" VaryByParam="GameID;Type" %>
<Scirra:ArcadeChartData ID="MyUserControlID" runat="server />
Full page code, MyArcadeChartData.aspx.cs
protected void Page_Load(object sender, EventArgs e)
{
//TODO: Put validation here
MyUserControlID.GameID = (int)Request.QueryString["GameID"];
MyUserControlID.Type = (YourEnum)Request.QueryString["Type"];
}
Please not that values in the QueryString can be seen by the user, please do not put sensitive data.
Also I’m aware that this isn’t the most professional solution, but it is the easiest to implement, from what I know.
Regards and happy holidays
If I understand right, the caching isn't working correctly because of the way you have the properties supplying the values to the control, which probably has to do, in part, with the calculations that are being done.
You could create an HttpHandlerFactory that takes the request, does your calculations if they're not in the cache (inserting into the cache afterwards), handles the expiration of values, and then passes the request on to the page. It wouldn't be control-specific at all. That way you could use these calculated values in any control or page, and wouldn't have to implement caching policies that worry about their own calculations.
If this isn't data intensive, have you considered storing it in the Session as apposed to caching it? Just a thought...
Arcade.ChartDataType.ChartType Type;
string GameKey = GameId + Type.toString();
storedData = callCalculation(GameId,Type);
Session[GameKey] = storedData;
I realize this isn't in the cache, I am just trying to be constructive.