I was to change some behaviour when the text attribute is set against a hyperlink. I know I can create my own version of like
public class MyHyperLink: System.Web.UI.Hyperlink
{
}
however, is it possible to override HyperLink one so I don't have to use a custom HyperLink class on the front end controls?
Related
I have a label and a button and when I press the button the label changes.
Now in order to continue i need to be able to access the label from another class. I tried to change the definition to public static in the aspx.designer.cs file but when I do that the button that changed the label before stopped working - i get a null exception. I tried to init the label but i can't find the right place to do it. Making a static method in the class, that will change the label's text didn't work as well because i can't change a non static variable in a static method.
How can I access a label from another class without getting a null exception or effecting the button that worked?
From a UserControl or a WebControl, you can access the Page with this.Page:
//From the Control File:
this.Page.TheLabel.Text = "blah";
Just make sure the label is public or you have a getter, and that you're not in a HttpContext (Not in a static method).
FIY, making the label static in the page would means there would only be one instance on the label shared by all the instance of pages. I doubt thats what you wants.
Better you can add a public property to the web control. Assign the label value to the public property and use it in any other place. It is better not to directly access label value from other files
This would seem to be very simple, but it's not working for me. I desparately need to know how to override the "Text" property of a server control I created, which inherits from "Label". When the control is dropped into an ASP Web form, I want the text property to already be set to a certain value. I tried:
[Browsable(true), Bindable(true), Category("Behavior"), Localizable(true)]
[DefaultValue("00:00:00")]
public override string Text{get; set;}
But it doesnt work; the "Text" property shows up blank - and when I try to edit it, I can change it to anything except the value specified in the "DefaultValue" attrib. This property is supposed to be overridable.
I also need to be able to set the "ID" property so it's set to a specific value when dropped on the form. Is this possible?
Any suggestions would be greatly appreciated!
For this you can use the ToolBoxDataAttribute:
Specifies the default tag generated for a custom control when it is
dragged from a toolbox in a tool such as Microsoft Visual Studio.
By default, the visual designer of a tool such as Visual Studio,
creates an empty tag. This is a tag representing a control in its
default state, when the control is dropped from the toolbox of a
visual designer onto the design surface. To specify initial default
values, a control can make use of this attribute. You can use this
attribute to customize the initial HTML content that is placed in the
designer when the control is dragged from the toolbox onto the form.
It would look something like this for your control:
[ToolBoxData("<{0}:TimeLabel ID='TL1' Text='00:00:00' runat='server' />")]
public class TimeLabel : System.Web.UI.WebControls.Label
{
[DefaultValue("00:00:00")]
public override string Text
{
get { return ViewState["Text"] != null ? (string)ViewState["Text"] : "00:00:00"; }
set { ViewState["Text"] = value; }
}
}
The DefaultValue attribute is intended to display a default value in Properties Tab.
So when you launch website without specify a value for your Text property .net uses this one.
IMHO you have not chance to do that. Sorry!
As my title says, I have a set property crash problem.
Here's the scenario:
I have created a simple custom ASP.Net server control that generates some text.
I wanted to give design-time property for that text so its style can be accessed by developers from the properties window.
All the properties in the properties window are working except the ones with the type System.Web.UI.WebControls.Style that I have created.
Here is my property:
[Bindable(true)]
[Category("Appearance")]
[Description("The style for the header")]
[Localizable(true)]
public Style HeaderTextStyle
{
get
{
Style s = (Style)(ViewState["HeaderTextStyle"] == null ? Styles.defaultHeaderStyle : ViewState["HeaderTextStyle"]);
return s;
}
set
{
ViewState["HeaderTextStyle"] = value;
}
}
Oh and Styles.defaultHeaderStyle is just a property from an internal class that returns a new Style.
Let me point that the hanging/crashing occurs only when I CHANGE the property, so it cannot be from the getter.
I won't paste my render control because the error occurs even when I'm not rendering anything.
What is it that causes this?
Thank you.
I found the answer to my problem.
You see, the Style class is a property that has sub-properties and it is called a complex property. Complex properties ( a property that has subproperties) need custom state management to use view state. The Style class need design-time attributes to enable persistence within the control's tags. So what I wrote in my original post will not work.
For complete explanation visit: Server Control Properties Example from MSDN
I managed to implement it using that example. I hope this will be useful to others out there.
I have created a class inherit from StateManagedCollection.
It has got a few class as Columns like GridView.
But I can not select which filed I want to select from.
It should look like the picture below in design.
But mine is the one below:
I have written the property as below:
[Description("A collection of ToolBarItem's ")]
[DesignerSerializationVisibility(DesignerSerializationVisibility.Content)]
[Editor(typeof(System.ComponentModel.Design.CollectionEditor), typeof(System.Drawing.Design.UITypeEditor)), PersistenceMode(PersistenceMode.InnerProperty)]
public virtual Items Items
{
}
Can anyone help me out?
GridView columns collection uses a custom UI Type editor to show this interface. The in-built ASP.NET CollectionEditor will not show the required UI. Further in your case, CollectionEditor may not work if the collection's item type is a abstract class.
Solution is to build your own custom UI Type editor - basic steps are
Inherit from System.Drawing.Design.UITypeEditor.
Override GetEditStyle method to inform the property browser that you will launch modal form.
Override the EditValue method to launch your custom UI form.
Build the custom UI Form.
See a couple examples here (see sample for TagTypeEditor) and here.
I'm working on a website that will allow instructors to report on the academic progress of students in their classes. I've got the website set up two primary pages: one with a user control that displays the classes (a GridView of basic class info with a child GridView in a template field that displays student names and checkboxes to select them -- called MiniStudents), and another with a user control that displays the selected students -- called FullStudents.
Although improbable, it's possible that an instructor could have the same student in two separate classes. I've already accounted for this in the current page setup -- the combination of student ID and class ID (class IDs change each quarter, for those thinking this will be an issue) form a unique key within the database. Recently, one of my users asked if I could break records out by classes on the page, so that instructors would be able easily recognize which class they're operating in.
So, my question is this: is it possible for me to dynamically add a column to the end of the class user control that would allow me to switch out MiniStudents for FullStudents?
If I've left out any important details or if anyone wants/needs code, please let me know.
Try this:
//Under page_load
string path;
if(condition) path = "~/MiniStudents.ascx";
else path = "~/FullStudents.ascx";
Control userControl = this.LoadControl(path);
panel1.Controls.Add(userControl);
And if you have specific properties that you want to set before the usercontrol gets rendered then make them inherit a custom usercontrol class:
public class CustomControl : UserControl
public class MiniStudents : CustomControl
public class FullStudents : CustomControl
So then you can do this:
CustomControl userControl = (CustomControl)this.LoadControl(path);
userControl.UserId = userId;
I hope this helps!
You could add both, and hide one or the other.
You could use a multiview control to control which control is visible. Though I would be concerned about your viewstate size if you are loading all these controls simulantously. It sounds like there could be a lot of data and markup on the page.