Context: ASP.NET 3.5 / C#
Hi,
I created a user control
public partial class MyControl : UserControl
{
// EDIT: example first used "UniqueId" as property name, which was wrong.
public Guid MyId { get; set; }
// ...
}
and this example usage
<uc1:MyControl
ID="myControl"
MyId="443CBF34-F75F-11DD-BE2F-68C555D89123"
runat="server" />
Steps:
Add this control to a web form (aspx)
Expected result:
the HTML for the user control is added, a unique value (corresponding to Guid.NewGuid()) for MyId is set in the ASPX HTML at design-time as the MyId attribute value.
Actual result:
the HTML for the user control is added, a unique value for MyId is not set in the HTML at design time for the MyId Attribute value.
If this is not possible:
Workaround 1: Would it be possible to achieve this using a server control? How?
Workaround 2: is it possible to achieve this using a UserControl design-mode task?
Clarification:
persisting the property value is not an issue, since it never changes for a control intance and is automatically set by ASP.NET through the control declaration in the aspx page.
the MyId attribute does not need to be rendered at runtime.
Gr B!
Custom Design-time Control Features in Visual Studio .NET
You have a couple problems here, but first I will answer your questions about the workarounds.
No you are already using a server control.
No design-mode is to just make the lives of the developer easy, it doesn't effect anything else
You have two problems here. There is already a property called UniqueID I don't know if you were trying to overload that, but the question wasn't clear. The second problem is that your UniqueID essentially not getting stored anywhere. Try the following code:
public Guid UniqueId {
get { return (Guid)ViewState["MyUserControlUniqueId"]; }
set { ViewState["MyUserControlUniqueId"] = value; }
}
That will store the GUID in the ViewState so that you can retrieve it on post backs.
Update: Given your comment you need to override/use this method to add attributes to the rendered content.
http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.webcontrol.addattributestorender.aspx
If I understand your question correctly, you are exposing a property on your user control called MyId. This allows you to set the property wherever you put that control.
What you also want, is for the rendered HTML to also include this attribute and value.
If that's the case, the property MyId is not passed through to the HTML, it's only because the user control has MyId as a property that it's visible in the designer.
In your user control you will have defined the markup that gets rendered.
So for example if you have:
<asp:Panel runat="Server" Id="myControlDiv">Some other content</asp:Panel>
You can then in your controls prerender event (or wherever else you choose) put
myControlDiv.Attributes.Add("MyId", SomeGuid.ToString())
Which will then get output in the HTML as
<div id="generatedID" MyID="443CBF34-F75F-11DD-BE2F-68C555D89123">Some other content</div>
So you just want a unique ID generated that you only ever use in design time?
Why not override Object.GetHasCode();
And then exposure this as a property?
Related
I have following user control my .ascx Page. (Test.ascx)
<uc:Addresses runat="server" itemId='<%# StringId %>'></uc:SNETAddresses>
In the code behind of Test.ascx I have
protected string StringId = "{2A06199B-ED96-42F0-AB9A-602139E58BFB}";
In the code behind of user control Addresses.cs I have:
public string itemId { get; set; }
So basically I want to pass a string to the variable itemId. But Somehow its not getting the value of variable "StringId". This simple thing is taking my so much time. I checked this post asp.net passing string variable to a user control but I am so sorry I could not get the answer. The reply is:
You may need to call DataBind on your Page in CreateChildControls or some other method
I am new to Asp.Net and I didn't get what the user mean here.
You need to call Page.DataBind(), e.g. in your Page_Load() event handler.
Data-binding expressions (<%# ... %>) are only processed when you call the DataBind() method.
Alternatively (instead of using a data-binding expression), you can also simply assign the value to the user control's property from your page's code-behind:
// add an ID to the user control (in the markup)
<uc:Addresses runat="server" id="myControl"></uc:SNETAddresses>
Then in your Page_Load() method simply assign the value to the user control's property:
myControl.itemId = StringId;
How to Access Controls from UserControls in ASPX page?
For example:
I want to access gridview which is in usercontrol on ASPX page.
Please help me.
Try this :
GridView GridView1 = (GridView)WebUserControl1.FindControl("GridView1");
Where WebUserControl1 is ID of use control on .aspx page.
Hope this helps..
The best way is to provide properties in your UserControl that you can access.
For example:
public GridView UserGrid
{
get
{
return GridView1;
}
}
But the question is why you need this.
Rule of thumb: Only expose as few as possible. On that way your code will be most robust and readable. So it would e.g. better to expose it's DataSource rather than the complete GridView.
On the other hand, if you want your page to react on events in your UserControl, it should provide custom events(e.g. UserDeleted) that your page then can handle.
Page-UserControl-Commmunication
Because the controls now nothing about eachother at the same level, you have to use the parent page to get it. Try this logic:
Create a property referring to your parent page (the page your control usually is in (might be different because of layering of controls)
Create a property on your page referring to the usercontrol the grid is in, or link to that grid directly.
page.aspx
public UserControl UserGridControl
{
get;
set;
}
userControl.ascx
public Page ParentPage
{
get;
set;
}
Example call:
Instantiate the properties first. After that, use the following statement to access anything from that control (as an example I used Foo() here, to use as a dummy method, but it seems it was unclear to someone):
otherControl.ascx:
this.ParentPage.UserGridControl.Foo();
EDIT: Want to have a direct code example to be able do it from the page only? See Tim Schmelters answer. If you need a way to call the grid from another user control as well. Use mine.
I would like to read the Form value of a control (e.g TextBox), i.e 'Request.Form["[Control_Name_Here]"]. The problem with using say TextBox.Text is because if you explicity set it yourself in the Page_Load, there is no way you can get back the 'original value' submitted in the form.
As you know, Asp.Net generates a unique ID/Name for the control. The Request.Form is based on the name attribute of a control. Each webcontrol has a ClientID property, however this does not match the name. The name seems to be almost like the ClientID, having $ instead of _. Is there a way to easily get the value from the form, without resorting to having to replace the _ to a $?
And this should also cater for other naming-conventions, because as from Asp.Net you can also choose to have a control's id statically-generated, rather than dynamically.
It sounds to me like you're not looking for the .ClientID property, but the .UniqueID property of the Control.
See: MSDN
Edit: Also, is there a reason you're always setting the .Text property within the page load? Instead of for example check the Page.IsPostBack property instead and only set the .Text if it's false?
I personally use jquery to find the control and read and set the value
GetFormValue = function (idName) {
var srchP = '[id='+idName+']';
var ctrl = $(srchP);
if (ctrl != null)
return ctrl.val();
return null;
}
so assume th id name in server part is txMytext
and it will be .....$txMytext in client
and by calling GetFormValue('txMytext') in client side you cna get the value of control
dont foget to use jquery library
I have seen two suggestions for my original question about whether it is possible to define a content area inside a user control and there are some helpful suggestions i.e.
Passing in content to ASP.NET user control
and
ASP.NET User Control inner content
Now, I like the theory of the latter better than the former just for aesthetic reasons. It seems to make more sense to me but the example given uses two variables content and templateContent that the answerer has not defined in their example code. Without these details I have found that the example does not work. I guess they are properties of the control? Or some such?
EDIT - DETAILS: What I am trying to do
I have need of an ASP.Net user control that conceals some content in a panel inside a placeholder and asks for the input of a code in a visible panel.
Essentially the user will put their code into the provided textbox in Panel A and submit it, it will be checked and, if it is valid, panel B and the locked content will be displayed.
I have done a test where the content was hard coded into panel B but as soon as I need to make the content a generic input it fails. If it were just text or somesuch then I could make it a property of the control, but as it is, in fact, another User Control I am having some difficulty getting this into the "hidden" panel.
Any other workable solutions are also welcome.
EDIT NOTE: The solution I'm trying to implement this in 2.0 I did find a 3.5 solution which I cannot use.
The former example seems workable but I'd prefer to go with the latter if someone could fill in the blanks for me.
Thanks.
Okay, so this is disturbingly easy but many of the tutorials on the web that talk about this kind of thing push to do extravagant things that require the control to parse ListItems or such.
So this solution is purely so that you can build a control that, for whatever reason, has a placeholder in it that could have anything inside it (kind of like a content area on a Master page). In this instance it happens to be because the Panel containing the placeholder is hidden until appropriate input actions have taken place in another panel.
First, you need to add this:
[ParseChildren(true,"Content")]
[PersistChildren(false)]
just above the part of the control which looks like this:
public partial class MyControl : System.Web.UI.UserControl
then in the control scoped declarations at the head of the control you want to declare thus:
private Control _content;
[PersistenceMode(PersistenceMode.InnerProperty)]
public Control Content { get { return _content; } set { _content = value; } }
Finally you need to place the content into the placeholder like this:
phContent.Controls.Add((Control)_content);
That last line goes into the Page_Init event. For reference "phContent" is the name of the place holder where you want the content to appear, like this:
<asp:Panel ID="pnlLockable" runat="server" Visible="False">
<asp:Placeholder runat="server" ID="phContent" />
</asp:Panel>
On the front end the resulting implementation looks like this:
<uc:MyControl runat="server" ID="lockit1">
<Content>
//...your stuff goes here...
</Content>
<uc:MyControl>
Note that I presume that what is inbetween the Content Tags is a root control. This is because I nested another user control in there. I imagine if you put whatever content you want within a panel or placeholder it should be fine.
Also you can read "How to: Create Templated ASP.NET User Controls". Really helpful.
I am developing a web application where I would like to perform a set of validations on a certain field (an account name in the specific case).
I need to check that the value is not empty, matches a certain pattern and is not already used.
I tried to create a UserControl that aggregates a RequiredFieldValidator, a RegexValidator and a CustomValidator, then I created a ControlToValidate property like this:
public partial class AccountNameValidator : System.Web.UI.UserControl {
public string ControlToValidate {
get { return ViewState["ControlToValidate"] as string; }
set {
ViewState["ControlToValidate"] = value;
AccountNameRequiredFieldValidator.ControlToValidate = value;
AccountNameRegexValidator.ControlToValidate = value;
AccountNameUniqueValidator.ControlToValidate = value;
}
}
}
However, if I insert the control on a page and set ControlToValidate to some control ID, when the page loads I get an error that says Unable to find control id 'AccountName' referenced by the 'ControlToValidate' property of 'AccountNameRequiredFieldValidator', which makes me think that the controls inside my UserControl cannot resolve correctly the controls in the parent page.
So, I have two questions:
1) Is it possible to have validator controls inside a UserControl validate a control in the parent page?
2) Is it correct and good practice to "aggregate" multiple validator controls in a UserControl? If not, what is the standard way to proceed?
Addressing your second question first- I don't think it's a good idea to "aggregate" validators together this way unless you include the controls you're validating in the user control. Too much work for not enough payoff.
You could fix this problem by exposing properties on your AggregatedValidator to set the names of the controls to validate, and pass in the ClientID of those controls you want validated.
I believe ASP.NET expects the ControlToValidate ID to be in the same naming container. You can probably override the validation method and use Parent.FindControl.
EDIT: This might be a good place to use a CompositeControl rather than a UserControl. They are designed for just this kind of aggregation. But you might have a similar NamingContainer issue.