If I create a UserControl, to create and edit an instance of a data class e.g. Person in C# WindowsForms (call it PersonControl), the framework automatically adds an instance of Person in PersonControl.Designer with some default values for the properties and fills the item controls with those values. This behavior has a number of side effects which I would like to avoid.
Question: is there a defined way to prevent creation of a data class instance in UserControl.Designer?
I think you missing the DesignerSerializationVisibility attribute. If you have a custom control every public property that you add will automatically be serialized. You can use this attribute to disable the serialization for a property. I also recommend to add the Browsable attribute which will hide the property from the designer. If you want more control over serialization, like you want to serialize only when another property is set to true you can create a special named method which will then called by the designer Defining Default Values with the ShouldSerialize and Reset Methods. There was a MSDN Magazine where a lots of winform learning resource was relased there are some gems about winform internal working. If you interested in you can quickly look trhrough it. My favorite is. Create And Host Custom Designers With The .NET Framework 2.0
Sorry but i didn't mention another attribute DefaultValue You can use the attribute the following way.
public partial class PersonEditControl : UserControl
{
[DefaultValue(null)] // This attribute tells the designer if the property value matches what we specified in the attribute(null) it should not store the property value.
public PersonData? Person { get; set; }
public PersonEditControl()
{
InitializeComponent();
}
}
Related
We're using Prism with UWP, and have a UserControl which we want to display several times in a Grid (each instance relating to a connected user).
If the UserControl were a Page, I know of course that the code can/should go in associated ViewModel. What's the equivalent for the UserControl? I obviously want to keep my code DRY, and call the same code for each UserControl instance.
My research is pointing me towards a Dependency Property, but I haven't found a clear example of how I should implement it.
Note that the UserControl needs to display data and also implement Buttons with associated Commands on the ViewModel.
Create a separate view model
You could create a view model specifically for the user control. The DataContext of the user control would be set to an instance of this view model. You can expose commands and data related to each user in the view model and bind to them in the user control, just like you would if it were a page.
This scenario works best if the user control can function independently of the page it is in. If you need the user control VM to communicate to the page VM, then you'll need to facilitate this somehow between the VMs (maybe the user control VM can take a reference to the page VM as a dependency upon construction).
Expose command properties in the user control
Another way is to create dependency properties for each command you want to expose in the user control, which can then be bound to in the page's XAML.
<UserControl>
<Grid>
<Button Content="Delete" Command="{x:Bind DeleteCommand}"/>
</Grid>
</UserControl>
public sealed partial class MyUserControl : UserControl
{
public ICommand DeleteCommand
{
get { return (ICommand)GetValue(DeleteCommandProperty); }
set { SetValue(DeleteCommandProperty, value); }
}
public static readonly DependencyProperty DeleteCommandProperty =
DependencyProperty.Register("DeleteCommand", typeof(ICommand), typeof(MyUserControl), new PropertyMetadata(null));
}
Now you can bind to DeleteCommand on the user control.
Typically I use some combination of both of these methods when I use user controls.
I have a custom Control which I'll call ccViewTemplate with this code in it:
<xp:repeat id="repeatData" rows="30"
value="#{viewEntry}" var="veData"
first="#{javascript:return (sessionScope.ssFirst != null)?sessionScope.ssFirst:0;}">
<xp:panel id="panelSelect">
<xp:callback facetName="viewBodyFacet" id="callback1"></xp:callback>
</xp:panel><!-- panelSelect -->
</xp:repeat>
the database view (viewEntry) is also defined in ccViewTemplate and defined based on several custom properties. ccViewTemplate is then added to another custom Control called ccFinalView. Where the custom properties are entered, and the content of the display is entered into viewBodyFacet. I have access to veData and a everything works great to this point. In the viewBodyFacet I have a link that does a redirect to open the document which also works fine. However, in the link I want to get the repeatData Property First and store it so that it returns to the correct page of the repeat. I use this code:
sessionScope.put('ssFirst',getComponent("repeatData").first);
However, the code can not find the getComponent("repeatData") because it is inside ccViewTemplate and not accessible. Is there a way to get the component repeatData from the ccViewTemplate while in ccFinalView which contains ccViewTemplate.
I have done getComponent("ccViewTemplate") and I have the handle to the custom Control, but
getComponent("ccViewTemplate").getComponent("RepeatData").first fails. So is there a way to pull a value from a component 'inside' a custom control from 'outside' the custome control?
looked a little further and found this:
var rtn = getComponent("ccViewTemplate").getPropertyMap().getProperty("repeatData");
It does not generate an error but returns nothing, if I add
var rtn = getComponent("ccViewTemplate").getPropertyMap().getProperty("repeatData").first;
I get an error getComponent() is null
Hope this makes sense.
From what I understand, this is a perfect job for a java bean. The bean can even keep a default value.
public class Controller{
public String value;
public Controller(){
value = "default_value";
}
public String getValue(){return value;}
public void setValue(String value){this.value=value}
}
In this fashion, the value will be available as soon as the object is created. pressing the button then sets the value with javascript,
ControllerBean.setValue("thisValue");
and you can read the value
ControllerBean.getValue();
This question shows how to configure the bean: How to set up a managed bean to work with Notes document
By setting this to, say the viewScope, you can then access the value anywhere you need regardless of whether or not it is in a custom control or main page. I highly recommend this approach. It just means possibly rethinking your custom control structure.
EDIT
Extra ideas include having an enum that maintains the views,
public enum Views{
VIEW_1("viewAlias", "urlParam")
private String vwAlias;
private String urlParam;
private Views(String alias, String param){
vwAlias = alias;
urlParam = param;
}
// public getters
}
And then in your controller you can get the view string:
1. By seeing if a view param is included in the URL
2. If a cookie value is set
3. Take the hard coded default
Clicking the change view action then sets the cookie value and changes the view parameter and redirects.
This is all extra ideas, but it is how I build my view controllers. I will be doing a tutorial on that soon.
I have a requirement where i need to weld a ContentPart to all the content types. Please guide me what is the best place to write this code.
I looked into the Orchard source code where InfosetPart is being welded with all content types in ContentHandlerBase's Activating method.
Following the InfosetPart weld mechanism i created one class inheriting from ContentHandlerBase and in Activating method i placed a break point with following condition which is getting hit again and again (more than once for one content type)
context.ContentType == "Page"
I'm not sure if it should be as it is because ideally it should hit this condition only once.
The way you are implementing it is correct. Your code is executed multiple times because content handlers are invoked for each content item, and not just for the content type. This also allows you to weld your part to only some of you content items, not all items of a specified type.
You wrote that you created a subclass of ContentHandlerBase. You should use ContentHandler as a base class.
Below is a simple code example how this should be done.
public class MyPartHandler : ContentHandler
{
protected override void Activating(ActivatingContentContext context) {
context.Builder.Weld<MyPart>();
}
}
I have a RPC method that returns a List of Strings. I want to create a ComboBox with a store that will load the values through a RpcProxy, but I can't find an example that doesn't use some sort of ModelData class.
I would prefer not to have to create a simple Bean with only one property (the string) and then have to convert the List one item at a time.
My ideal would be to create something like this:
RpcProxy<List<String>> proxy = new RpcProxy<List<String>>()...
Any suggestions?
Unfortunately, with GXT 2.2.5, you can't get around not using ModelData.
The class definition for ComboBox says it all:
public class ComboBox<D extends ModelData> extends TriggerField<D> implements SelectionProvider<D> {
...
protected ListStore<D> store;
...
So, at this point your biggest concern is keeping your code clean. If you have to make a specialized ModelData derived class, you could subclass ComboBox and keep a nested class definition for your wrapper object.
If you're not tied to using GXT 2.2.5, I would update to GXT 3.0.x and GWT 2.5.0. GXT 3 moved away from using ModelData. Now, everything accepts bean-like objects.
I'm trying to modify the EditorPart controller for my web part. Basically what I want is to have my custom controls inside a box like the standard properties that can toggle between visible and hidden.
I've been googling for a while, but I cannot seem to find an answer.
Just to clarify: I know I can use the Category property to accomplish this when adding web part properties directly to the web part, but I've extended the EditorPart controller and so I don't think I can simply add [Category("Feed settings")] to the TextBox and LiteralControls I'm creating (correct?).
What you'd need for a standard property is to mark it with the Category attribute:
[Category("My Category")]
public string FeedQuery { get; set; }
(You'll need to add the System.ComponentModel namespace to your class file).
For editor parts it is not so simple. It appears that you can't add them to the standard categories. It is possible to style the editor part to resemble the OOB panels as shown here