Can I data bind two proporties values in a single textblock.
For Example some thing like following, though this is noth the correct code:
<TextBlock Margin="5" Text="{Binding property1,Binding property2}" Style="{StaticResource Style1}" />
I want to display two values in a single text block .
Thanks,
Subhendu
When you use MVVM you would typically create a third property that concatenates the two others and bind to that one.
public string Prop1 { get; set; }
public string Prop2 { get; set; }
public string Prop3 { get {return string.Format("{0} {1}", Prop1, Prop2); } }
In you xaml, you would then bind to Prop3. If you want two way binding, you can implement a setter for Prop3 that updates Prop1 and Prop2.
Cheers,
Phil
mmm, AFIK you can't do that.
however, you CAN do it a couple of ways.
One, create a Converter that takes your object and returns the two properties
public class Formatter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
// do some stuff with value to get your information
return myvalue;
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
throw new NotImplementedException();
}
}
// make a static resource of your converter
<Resources>
<myns:Converter x:Key="MyConverter"/>
</Resource>
// now use it in your binding
second, you can nest textblocks like so (well, maybe not in silverlight, but in WPF you can) ...
<TextBlock ...>
<TextBlock .../>
<TextBlock .../>
</TextBlock>
Related
How to present a string, number or a also view model with binding and DataTemplate?
I am looking for a MAUI replacement for the WPF ContentControl.
The ContentView has a Content property but this is from type View.
The ContentPresenter has a Content property but this is also from type View. <Ignorable>WTF, Why this is not named ViewPresenter when it can only present a View??? Someoteimes MAUI is weird.</Ignorable>
How to present any content with defining DataTemplates for each data type?
class PropertyViewModel {
public string Name {get;set;}
public object Value {get;set;}
}
<Page.Resources>
<DataTemplate DataType="System.String">
<Entry Text="{Binding}/>
</DataTemplate>
<DataTemplate DataType="System.Int32">
<NumberPicker Value="{Binding}/>
</DataTemplate>
.. more templates, eg. DatePicker for System.DateOnly
</Page.Resources>
<DockLayout>
<Label Text="{Binding Name}
<TemplatedContenView Content={Binding Value}/>
</DockPanel>
The TemplatedContenView or ContentControl (that does not exist in MAUI), can use different templates for different types of Value. In WPF the ContentControl uses ContentTemplate, ContentTemplateSelector or if none specified it looked into the resources to find the template.
<Ignorable>I often have the feeling with MAUI that I have to constantly reinvent things that are standard in WPF. Yes I know MAUI is not WPF, but there should still be at least similar concepts. The switch from WinForms to WPF was much easier and the differences were considerably greater.</Ignorable>
Edit1: a more detailed example
I'm a WPF developer and recently I've started MAUI project. And It looks like you have to reinvent the wheel every time when you are going to write such a simple scenario as you mentioned :(. When you do it using WPF you even don't need to thought about that, it's too easy to implement, but when you use MAUI you should break your mind to do such minor things.
I also encountered the same issue and I didn't find a simple in-box solution. But I came up with the idea to create a control with some layout inside that has attached properties from BindableLayout
TemplatedContentPresenter.xaml.cs:
public partial class TemplatedContentPresenter : ContentView
{
public TemplatedContentPresenter()
{
InitializeComponent();
}
public static readonly BindableProperty DataTemplateSelectorProperty = BindableProperty.Create(nameof(DataTemplateSelector), typeof(DataTemplateSelector), typeof(TemplatedContentPresenter), null, propertyChanged: DataTemplateSelectorChanged);
public static readonly BindableProperty DataTemplateProperty = BindableProperty.Create(nameof(DataTemplate), typeof(DataTemplate), typeof(TemplatedContentPresenter), null, propertyChanged: DataTemplateChanged);
public static readonly BindableProperty DataProperty = BindableProperty.Create(nameof(Data), typeof(object), typeof(TemplatedContentPresenter), null, propertyChanged: DataChanged);
public DataTemplateSelector DataTemplateSelector
{
get =>(DataTemplateSelector)GetValue(DataTemplateSelectorProperty);
set => SetValue(DataTemplateSelectorProperty, value);
}
public DataTemplate DataTemplate
{
get => (DataTemplate)GetValue(DataTemplateProperty);
set => SetValue(DataTemplateProperty, value);
}
public object Data
{
get => GetValue(DataProperty);
set => SetValue(DataProperty, value);
}
private static void DataTemplateSelectorChanged(BindableObject bindable, object oldValue, object newValue)
{
if(bindable is TemplatedContentPresenter contentPresenter && newValue is DataTemplateSelector dataTemplateSelector)
{
BindableLayout.SetItemTemplateSelector(contentPresenter.HostGrid, dataTemplateSelector);
}
}
private static void DataTemplateChanged(BindableObject bindable, object oldValue, object newValue)
{
if (bindable is TemplatedContentPresenter contentPresenter && newValue is DataTemplate dataTemplate)
{
BindableLayout.SetItemTemplate(contentPresenter.HostGrid, dataTemplate);
}
}
private static void DataChanged(BindableObject bindable, object oldValue, object newValue)
{
if (bindable is TemplatedContentPresenter contentPresenter)
{
BindableLayout.SetItemsSource(contentPresenter.HostGrid, new object[] { newValue });
}
}
}
TemplatedContentPresenter.xaml:
<?xml version="1.0" encoding="utf-8" ?>
<ContentView xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="MyApp.TemplatedContentPresenter">
<Grid x:Name="HostGrid" x:FieldModifier="private" />
</ContentView>
Usage:
<Frame WidthRequest="500" HeightRequest="500">
<controls:TemplatedContentPresenter
Data="{Binding}"
DataTemplateSelector="{StaticResource CardTemplateSelector}"/>
</Frame>
UPD:
While I was writing the answer I came up with another solution with a simple converter:
SingleObjectToArray.xaml
internal class SingleObjectToArray : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
return new object[] { value };
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
}
Usage:
<Frame>
<Frame.Resources>
<converters:SingleObjectToArray x:Key="SingleObjectToArrayConverter"/>
</Frame.Resources>
<Grid BindableLayout.ItemsSource="{Binding Converter={StaticResource SingleObjectToArrayConverter}}"
BindableLayout.ItemTemplateSelector="{StaticResource CardTemplateSelector}" />
</Frame>
I'm new to MVVMCross and trying to change keyboard type of Input field based on setting. I tried to achieve this by creating convertor but no luck. Please help me if you can.
Thank you in advance.
You can customize your keyboard with Keyboard property, as following shows
Chat – used for texting and places where emoji are useful.
Default – the default keyboard.
Email – used when entering email addresses.
Numeric – used when entering numbers.
Plain – used when entering text, without any KeyboardFlags specified.
Telephone – used when entering telephone numbers.
Text – used when entering text.
Url – used for entering file paths & web addresses.
Here is a document you can refer to https://learn.microsoft.com/en-us/xamarin/xamarin-forms/user-interface/text/entry
Update:
I bind the switch with Entry.Keyboard using Converter code like following:
<ContentPage.Content>
<StackLayout Orientation="Horizontal"
VerticalOptions="CenterAndExpand">
<Label Text="switch keyborad"/>
<Entry BackgroundColor="AliceBlue">
<Entry.Keyboard>
<Binding Source="{x:Reference myswitch}"
Path="IsToggled">
<Binding.Converter>
<local:KeyboardConverter x:TypeArguments="Keyboard"
TrueValue="Keyboard.Chat"
FalseValue="Keyboard.Numeric"/>
</Binding.Converter>
</Binding>
</Entry.Keyboard>
</Entry>
<Switch x:Name="myswitch"/>
</StackLayout>
</ContentPage.Content>
Converter:
public class KeyboardConverter<T>:IValueConverter
{
public T TrueValue { set; get; }
public T FalseValue { set; get; }
public KeyboardConverter()
{
}
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
return (bool)value ? TrueValue : FalseValue;
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
return ((Object)value).Equals(TrueValue);
}
}
<ContentPage.Content>
<StackLayout Orientation="Horizontal"
I try to set the values of a selectManyCheckbox to my testBean backing bean.
If I use a property of type List<String> instead of Attributed<List<String>> it works perfectly. It is the workaround I'm using currently.
But on my backing bean I have a generic object which contains the List.
The javax.el.BeanELResolver resolve this to an Object. Which is correct due to Type erasure.
I tried to implement a custom ElResolver. But I should know to which type to convert the object to. It isn't obviously always a List. I have the information in the xhtml pages. So I hoped I could pass some child element which would contain the information, but could not find a way to access the child element from the ElResolver.
A Custom converted does not work either as it converts selectItems, not the List.
Here is the simplest form
<h:form>
<p:selectManyCheckbox value="#{testBean.attributed.value}" >
<f:selectItems value="#{testBean.selection}" />
</p:selectManyCheckbox>
<p:commandButton action="#{testBean.execute}" value="do it" />
</h:form>
and the bean
private Attributed<List<String>> attributed = new Attributed<>();
public Map<String, String> getSelection() {
return ImmutableMap.<String, String> of("key1", "value1", "key2", "value2");
}
public static class Attributed<T> {
private T value;
public T getValue() {
return value;
}
public void setValue(T value) {
this.value = value;
}
}
public Attributed<List<String>> getAttributed() {
return attributed;
}
public void setAttributed(Attributed<List<String>> attributed) {
this.attributed = attributed;
}
So the question is:
Is there a way to set the value to testBean.attributed.value directly and with the correct type.
Is it possible by defining a custom ElResolver, or are there other way to do it?
I'm using ASP.NET MVC 4 for an internal web application and I have a desire to bind HTML input fields to a custom object rather than string.
In the HTML I have input fields that will look like the following:
<input type="hidden" name="First" value="1;Simple" />
<input type="hidden" name="First" value="2;Sample" />
<input type="hidden" name="Second" value="1;Over" />
<input type="hidden" name="Third" value="22;Complex" />
<input type="hidden" name="Third" value="17;Whosit" />
This will happily bind to ViewModel properties like:
public string[] First { get; set; }
public string[] Second { get; set; }
public string[] Third { get; set; }
Each string is a delimited string of key+value that I'd love to have automatically parsed into a concrete object (I have one already defined.) Ideally I'd want it to bind exactly as above but using my object that would know how to split the delimited string into the proper properties.
I can't figure out how to get MVC to bind to a custom object. I've used constructors and implicit operator definitions but I can't get it to work with anything but string datatype.
I know I could get this to work if I pre-split the values into pairs in the HTML but I'm using a JavaScript library that doesn't give this ability. For instance I know repeating {name}.Label and {name}.Value would work to bind to the string properties on my complex object but this is prohibitive and a non-starter.
I have gotten this to work with a custom object to handle File Uploads but I suspect that worked only because it inherited from the same base object. I can't do this here since string is a sealed type and can't be extended.
My last resort is to find the default model binder code and reflect that to figure out how it's assigning the values to see if it teaches me anything that I can override. I'd prefer not to go the route of a custom binder I'd have to write myself and if it comes down to it I'll just have duplicate ViewModel fields and convert them myself but I'd really love to avoid this if there's already a capability for the model binder to do this for me.
Here is what you can do. Let's say your MyThing class is something like this:
public class MyThing
{
public int Id { get; set; }
public string Name { get; set; }
public override string ToString()
{
return string.Format("{0};{1}", this.Id, this.Name);
}
}
Then, you can create a custom model binder for it like below:
public class MyModelBinder : IModelBinder
{
public object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
{
ValueProviderResult valueResult = bindingContext.ValueProvider
.GetValue(bindingContext.ModelName);
ModelState modelState = new ModelState { Value = valueResult };
object actualValue = null;
if (valueResult != null && !string.IsNullOrEmpty(valueResult.AttemptedValue))
{
if(valueResult.AttemptedValue.Contains(';'))
{
try
{
var attemptedValue = valueResult.AttemptedValue.Split(';');
int id = int.Parse(attemptedValue.First());
string name = attemptedValue.Last();
actualValue = new MyThing { Id = id, Name = name };
}
catch(Exception e)
{
modelState.Errors.Add(e);
}
}
else
{
modelState.Errors.Add("Invalid value.");
}
bindingContext.ModelState.Add(bindingContext.ModelName, modelState);
}
return actualValue;
}
}
You'll need to register your ModelBinder in Application_Start event of Global.asax like this:
ModelBinders.Binders.Add(typeof(MyThing), new MyModelBinder());
The question didn't get a single bite so I looked at the default model binder to see what was happening under the covers. There are a number of stages it goes through to see if a value can be converted to the ViewModel type but most of them are inaccessible to me. I did find a segment of code that fell back to using a type converter which I'd never used before.
Using this MSDN Type Converter how-to, I made a simple converter and decorated my class with the appropriate attribute and it just worked. I'm not sure what the performance implications are but it really simplifies my ViewModel code.
This example below is working for me. Keep in mind I'm only converting from the simple string type used by the DefaultModelBinder so it doesn't look like it's doing much but it solves my need and taught me a new feature of the framework.
public class MyThingConverter : TypeConverter
{
public override bool CanConvertFrom(ITypeDescriptorContext context,
Type sourceType)
{
if (sourceType == typeof(string))
return true;
return base.CanConvertFrom(context, sourceType);
}
public override object ConvertFrom(ITypeDescriptorContext context,
CultureInfo culture, object value)
{
if (value is string)
return new MyThing((string)value);
return base.ConvertFrom(context, culture, value);
}
}
[TypeConverter(typeof(MyThingConverter))]
public class MyThing
{
public MyThing(string combinedValue)
{
//Split combinedValue into whatever properties I need
...
}
public override string ToString()
{
return string.Format("{0};{1}", prop1, prop2);
}
...
}
And that's it. So far it's working as expected.
i want to model bind this this data that is sent from the client
tag[15-d] : Little Owl
tag[19-a] : Merlin
name : value
into IEnumrable<AutoCompleteItem>
public class AutoCompleteItem
{
public string Key { get; set; }
public string Value { get; set; }
}
for example
Key = 15-d
Value = Little Owl
i don't know how to implement my own model binder in this scenario , any solution ?
Here is a model binder that I did for you and does what you want. It by no means complete (no validation, no error checking etc), but it can kick start you. One thing I particularly dislike is that the ModelBinder directly accesses the form collection instead of using the ValueProvider of the context, but the latter doesn't let you get all bindable values.
public class AutoCompleteItemModelBinder : IModelBinder
{
// Normally we would use bindingContext.ValueProvider here, but it doesn't let us
// do pattern matching.
public object BindModel (ControllerContext controllerContext, ModelBindingContext bindingContext)
{
string pattern = #"tag\[(?<Key>.*)\]";
if (!String.IsNullOrWhiteSpace (bindingContext.ModelName))
pattern = bindingContext.ModelName + "." + pattern;
IEnumerable<string> matchedInputNames =
controllerContext.HttpContext.Request.Form.AllKeys.Where(inputName => Regex.IsMatch(inputName, pattern, RegexOptions.IgnoreCase));
return matchedInputNames.Select (inputName =>
new AutoCompleteItem {
Value = controllerContext.HttpContext.Request.Form[inputName],
Key = Regex.Match(inputName, pattern).Groups["Key"].Value
}).ToList();
}
}
Here is a sample action that uses it:
[HttpPost]
public void TestModelBinder ([ModelBinder(typeof(AutoCompleteItemModelBinder))]
IList<AutoCompleteItem> items)
{
}
And a sample view. Note the "items." prefix - it's the Model Name (you can drop it depending on how you submit this list of items:
#using (Html.BeginForm ("TestModelBinder", "Home")) {
<input type="text" name="items.tag[15-d]" value="Little Owl" />
<input type="text" name="items.tag[19-a]" value="Merlin" />
<input type="submit" value="Submit" />
}
If you have questions - add a comment and I will expand this answer.
You should just be able to name your fields key[0], value[0] (1,2,3 etc) and it should bind automatically since these are just strings. If you need to customize this for some reason - still name your fields key[0] value[0] (then 1,2,3 etc) and do exactly as specified here:
ASP.NET MVC - Custom model binder able to process arrays