Is it possible to create a hierarchical grid dynamically, with an arbitrary number of Master-Detail levels ?
You can use auto generated hierarchy. It is working with DataSets and it is out of the box functionality for the radgrid:
<telerik:RadGrid ID="RadGrid1" runat="server" OnNeedDataSource="RadGrid1_NeedDataSource" AutoGenerateHierarchy="true">
</telerik:RadGrid>
Code behind:
protected void RadGrid1_NeedDataSource(object source, Telerik.Web.UI.GridNeedDataSourceEventArgs e)
{
RadGrid1.DataSource = MyDataSet;
}
Check this link which demonstrates that functionality.
Related
When I try to use the method to inflate my XAML:
MenuBarItem item = new().LoadFromXaml("<MenuBarItem Text=\"Session\"><MenuFlyoutItem Text=\"New\"/><MenuFlyoutItem Text=\"Save\"/><MenuFlyoutItem Text=\"Load\"/></MenuBarItem>");
the MenuBarItem is created and Text properly assigned but all the MenuFlyoutItems are ommited and not added to the menu.
After reading Load XAML at runtime documentation and particularly the "The LoadFromXaml method can be used to inflate any XAML" and the examples given, I assumed that I can throw any valid XAML into it - from a single button, to a DataTemplate of a ListView, a MenuBarItem for a menu, to a whole ContentPage and it should work. But it's not working in this case - I get Microsoft.Maui.Controls.Xaml.XamlParseException and System.Reflection.TargetInvocationException.
Is this behavior a bug or is documentation missing some details about loading XAMLs?
When I enclose the MenuBarItem in a ContentPage's MenuBarItems like this:
new ContentPage().LoadFromXaml("<?xml version=\"1.0\" encoding=\"utf-8\"?>\r\n<ContentPage\r\n\txmlns=\"http://schemas.microsoft.com/dotnet/2021/maui\"\r\n\txmlns:x=\"http://schemas.microsoft.com/winfx/2009/xaml\"\r\n\tx:Class=\"LoadRuntimeXAML.CatalogItemsPage\"\r\n\tTitle=\"Catalog Items\">\r\n\t<ContentPage.MenuBarItems>\r\n\t\t<MenuBarItem Text=\"Session\">\r\n\t\t\t<MenuFlyoutItem\r\n\t\t\t\tText=\"New\"/>\r\n\t\t\t<MenuFlyoutItem\r\n\t\t\t\tText=\"Save\"/>\r\n\t\t\t<MenuFlyoutItem\r\n\t\t\t\tText=\"Load\"/>\r\n\t\t</MenuBarItem>\r\n\t</ContentPage.MenuBarItems>\r\n</ContentPage>");
it inflates without error and then when I assign elements from the inflated ContentPage to the MainPage's MenuBarItems they display well. But this is an ugly workaround because I don't need a whole ContentPage, just the MenuBarItem.
Your XAML is not complete, thus cannot be parsed.
What the ContentPage has, that your XAML lacks, is the various xmlns lines, that specify the XML elements used in the XAML.
I have not tested, but try replacing <MenuBarItem with
<MenuBarItem\r\n\txmlns=\"http://schemas.microsoft.com/dotnet/2021/maui\"\r\n\txmlns:x=\"http://schemas.microsoft.com/winfx/2009/xaml\"\r\n
Adapt as needed. Any whitespace can be used anywhere \r\n is shown.
If it doesn't work, also prefix with:
<?xml version=\"1.0\" encoding=\"utf-8\"?>\r\n
But I believe that is optional.
As an aside, anything that can be done in XAML, can instead be done in C#. C# markup.
C#, being a complete computational language, can often create dynamic UI more easily than XAML, if you are building a UI that depends on different conditions.
A convenient approach in C#, is to define "helper" methods, that take whatever parameters you want, and creates a specific element. That you add to a given parent element, either via C# markup, or methods of a parent layout class.
Its easy to write helper methods that call other helper methods, to build up a whole layout to your specs, controlled at each step by the parameters that matter to you.
At the top level, you might end up with code like this:
// use custom helper methods and methods of "Grid" class.
Grid grid = MyCreateGrid();
grid.Children.Add(MyCreateRowLabel(text), 1, 0);
grid.Children.Add(
// OR use C# markup
new StackLayout
{
Children =
{
new Label().Text("Code:"),
...
}
},
1, 1
);
...
From the official document, it's only using LoadFromXaml for single view or a complete contentPage. I also tried LoadFromXaml for <MenuBarItem Text=\"Session\"><MenuFlyoutItem Text=\"New\"/><MenuFlyoutItem Text=\"Save\"/><MenuFlyoutItem Text=\"Load\"/></MenuBarItem>, and just you said that:
the MenuBarItem is created and Text properly assigned but all the MenuFlyoutItems are ommited and not added to the menu.
But you can achieve it by doing this:
MainPage.xaml:
<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="MauiApp_loadXaml.MainPage"
x:Name="contentPage">
<Button Text="click" Clicked="Button_Clicked" HeightRequest="50"/>
</ContentPage>
MainPage.xaml.cs:
private void Button_Clicked(object sender, EventArgs e)
{
var xaml = "<MenuBarItem Text=\"Session\"></MenuBarItem>";
var xaml1 = "<MenuFlyoutItem Text=\"New\"/>";
var xaml2 = "<MenuFlyoutItem Text=\"Save\"/>";
var xaml3 = "<MenuFlyoutItem Text=\"Load\"/>";
MenuFlyoutItem menuFlyoutItem_1 = new MenuFlyoutItem().LoadFromXaml(xaml1);
MenuFlyoutItem menuFlyoutItem_2 = new MenuFlyoutItem().LoadFromXaml(xaml2);
MenuFlyoutItem menuFlyoutItem_3 = new MenuFlyoutItem().LoadFromXaml(xaml3);
MenuBarItem item = new MenuBarItem();
item.LoadFromXaml(xaml);
item.Add(menuFlyoutItem_1);
item.Add(menuFlyoutItem_2);
item.Add(menuFlyoutItem_3);
contentPage.MenuBarItems.Add(item);
}
It works well.
I'm trying to add to an existing xamarin.forms page, chunks of xaml that will be generated dynamically.
I'm starting my research using the following example from the official docs.
Everything works fine there, but when I try to change the string with the button def for a string with the stacklayout with the button inside, only the stacklayout is inflated, with no children at all.
That's weird, because you can inflate a full page in the example, but it looks like I'm missing something here.
Any advice about how to use LoadFromXaml for partial composite objects?
// MainPage.xaml.cs
void OnLoadButtonClicked(object sender, EventArgs e)
{
string navigationButtonXAML = "<StackLayout><Button Text=\"Navigate\" /></StackLayout>";
var sl = new StackLayout().LoadFromXaml(navigationButtonXAML);
_stackLayout.Children.Add(sl);
}
From the official doc, it's only using LoadFromXaml for single view or a complete contentPage, I also tried LoadFromXaml for layout, and it's loading the layout without its children. For loading layout with children, I'm try debugging with source code, will update later, and as a workaround, you can use layout with contentview like this:
string navigationStackLayoutXAML = "<?xml version=\"1.0\" encoding=\"UTF-8\"?><ContentView xmlns=\"http://xamarin.com/schemas/2014/forms\" xmlns:x=\"http://schemas.microsoft.com/winfx/2009/xaml\" xmlns:d=\"http://xamarin.com/schemas/2014/forms/design\" xmlns:mc=\"http://schemas.openxmlformats.org/markup-compatibility/2006\" mc:Ignorable=\"d\" x:Class=\"LoadRuntimeXAML.CustomerViewDemo\"> <ContentView.Content> <StackLayout > <Label Text=\"Hello Xamarin.Forms!\" /> <Button Text=\"SECONDB\"/> </StackLayout> </ContentView.Content> </ContentView>";
ContentView contentView = new ContentView().LoadFromXaml(navigationStackLayoutXAML);
_stackLayout.Children.Add(contentView);
Although it's xaml is a little bit more complex, but it can use predefined attributes just as in .xaml, also, elements inside the contentView will be accessible through:
Button secondB = contentView.FindByName<Button>("secondB");
how can I manipulate the View (XAML) from my ViewModel?
For example, I have a detail view for an object. The view have a grid. Depending of the object, the Grid should have different count of rows and cols. The number of cols and rows is set in the object details. Is it possible to do that from the ViewModel or I have to do that in the View .cs?
I open the detail view from a ListView (OnItemSelect):
await Navigation.PushAsync(new AlgoDetailPage(new AlgoDetailViewModel(algo)));
AlgoDetailPage - Here I want to add the cols and rows, depending of the object.
<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="NotsanHessen.Views.AlgoDetailPage"
Title="{Binding Algo.Title}">
<StackLayout>
<Grid>
</Grid>
</StackLayout>
</ContentPage>
The AlgoDetailPage.cs:
public partial class AlgoDetailPage : ContentPage
{
AlgoDetailViewModel viewModel;
public AlgoDetailPage(AlgoDetailViewModel viewModel)
{
InitializeComponent();
BindingContext = this.viewModel = viewModel;
}
public AlgoDetailPage()
{
InitializeComponent();
BindingContext = viewModel;
}
}
The ViewModel:
public class AlgoDetailViewModel : BaseViewModel
{
public Algo Algo { get; set; }
public AlgoDetailViewModel(Algo algo = null)
{
this.Algo = algo;
// Rows: algo.Rows
// Cols: algoCols
}
}
you don't manipulate the View from the VM. Instead, the View should use the VM's properties to determine it's layout. In this case, you would add the rows and cols in the View based on the data from the VM.
Technically, you don't have to do that from View itself. If you want to be exactly orthodox you can create the custom control that will handle the binding for you. Personally I wouldn't recommend this level of following some theory, but if you want it it is possible.
Other than that you may try to take a look at CollectionView that will appear in Xamarin 4.0 it may be close to what you have requested (you haven't specified exactly how column width is to be handled). Also there could be some 3rd party components that can handle this.
If it is a complex grid, have two different content views. In your xaml, based on the condition show or hide the content views. In this way, you can keep the code manageable any time.
And if you REALLY necessarily want to access the View from ViewModel, you can Bind View's Load Event to a Command and pass the View itself as a Command Parameter.
I'm developing a WP7 application, and I'm generating a listbox with a few items. I was wondering if there is a way to preview how the layout would look. So far, since the elements don't exist, I can't "preview" them.
Is there some way to feed some dummy data or other methods that would help in previewing xaml layouts ?
First - it helps if you use MVVM, or at least ItemsSource binding + ItemTemplate to display your items. Once you are there - Expression Blend has some great tools for sample data.
You go to Data tab, click Create Sample Data/New Sample Data. It will create a sample data as XAML and bind your page to it like that:
d:DataContext="{d:DesignData SampleData/MainViewModelSampleData.xaml}"
Then you can add new properties, model collections with different data types and it will automatically generate some data you can use in your XAML.
You should provide a designer data.
There are several ways to do it.
One of the simplest, is to provide a DataContext in your XAML declaration for designer to use when rendering your page display.
In Xaml page declaration:
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
d:DataContext="{d:DesignInstance local:DesignerSampleData, IsDesignTimeCreatable=True}"
The sample data class should have the data that your visual elements bind to:
public class DesignerSampleData: INotifyPropertyChanged
{
public DesignerSampleData()
{
_sampleData = "My test string that will display in VS designer for preview";
}
private String _sampleData;
public String SampleData
{
get { return _sampleData; }
set
{
if (value != _sampleData)
{
_sampleData = value;
NotifyPropertyChanged("SampleData");
}
}
}
In xaml bind to SampleData:
<TextBlock Text="{Binding SampleData}" />
As a new .net/C# web begginner, I always get tripped up when I try to use FindControl. Blam -flat on my face. Here is my current FindControl problem:
I have an .aspx page and Form, then ajax updatePanel, inside it there is my DataList (DataList1) that has an EditItemTemplate: that has the following:
<EditItemTemplate>
<asp:Label ID="thumbnailUploadLabel" runat="server" text="Upload a new thumbnail image:"/><br />
<asp:FileUpload ID="thumbnailImageUpload" runat="server" />
<asp:Button ID="thunbnailImageUploadButton" runat="server" Text="Upload Now" OnClick="thumbnailUpload"/><br />
</EditItemTemplate>
In my C# code behind I have the OnClick code for the fileUpload object:
protected void thumbnailUpload(object s, EventArgs e)
{
if (thumbnailImageUpload.HasFile)
{
//get name of the file & upload
string imageName = thumbnailImageUpload.FileName;
thumbnailImageUpload.SaveAs(MapPath("../../images/merch_sm/" + imageName));
//let'em know that it worked (or didn't)
thumbnailUploadLabel.Text = "Image " + imageName + "has been uploaded.";
}
else
{
thumbnailUploadLabel.Text = "Please choose a thumbnail image to upload.";
}
So of course I'm getting "Object reference not set to an instance of an object" for the FileUpload and the Label.
What is the correct syntax to find these controls, before dealing with them in the OnClick event?
The only way Ive used FindControl is something like:
label thumbnailUploadLabel = DataList1.FindControl("thumbnailUploadLabel") as Label;
But of course this is throwing the "Object reference not set to an instance of an object" error. Any help is very much appreciated.
(I've also seen the 'recursive' code out there that is supposed to make using FindControl easier. Ha! I'm so green at C# that I don't even know how to incorporate those into my project.)
Thanks to all for taking a look at this.
I know this is a hell lot late but i was looking for questions to answer....you must have figured it by now but still
if you add these lines in your code
protected void thumbnailUpload(object sender, EventArgs e)
{
FileUpload thumbnailImageUpload =(FileUpload)DataList1.Items[DataList1.EditItemIndex].FindControl("thumbnailImageUpload");
Label thumbnailUploadLabel = (Label)DataList1.Items[DataList1.EditItemIndex].FindControl("thumbnailUploadLabel");
if (thumbnailImageUpload.HasFile)
{
//Your code here
}
else
{
thumbnailUploadLabel.Text = "Please choose a thumbnail image to upload.";
}
}
this will find the appropriate control for the row you are editing...
also keep your Datalist out of the UPdate Panel beacuse Update Panels are not compatible with FileUpload. if you do the code will run but it will always show thumbnailImageUpload.HasFile as False.