how to declare xmlns:local to a subfolder within my xamarin forms app? - xaml

Question

Hello I'm working on a xamrain forms app that has a main menu and when you click the math button it supposed to take you to the MathHome page however it crashes after you click the button on the home page
heres my code for the mathpage:
<?xml version="1.0" encoding="UTF-8"?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:local="clr-namespace:SchoolTools.Math.ViewModels;assembly=SchoolTools"
x:Class="SchoolTools.MathPage">
<ContentPage.Resources>
<ResourceDictionary>
<Style x:Key="NumberStyle" TargetType="Button">
<Setter Property="BackgroundColor" Value="White"/>
<Setter Property="TextColor" Value="Black"/>
<Setter Property="BorderRadius" Value="0"/>
<Setter Property="Font" Value="36"/>
</Style>
<Style x:Key="OperationsStyle" TargetType="Button">
<Setter Property="BackgroundColor" Value="#FFA500"/>
<Setter Property="TextColor" Value="White"/>
<Setter Property="BorderRadius" Value="0"/>
<Setter Property="Font" Value="36"/>
</Style>
<Style x:Key="BackSpaceButtonStyle" TargetType="Button">
<Setter Property="BackgroundColor" Value="Black"/>
<Setter Property="TextColor" Value="White"/>
<Setter Property="BorderRadius" Value="0"/>
<Setter Property="Font" Value="Bold,40"/>
<Setter Property="VerticalOptions" Value="CenterAndExpand"/>
<Setter Property="HorizontalOptions" Value="CenterAndExpand"/>
</Style>
<Style x:Key="CleanButtonStyle" TargetType="Button">
<Setter Property="BackgroundColor" Value="Teal"/>
<Setter Property="TextColor" Value="Black"/>
<Setter Property="BorderRadius" Value="0"/>
<Setter Property="Font" Value="36"/>
</Style>
<Style x:Key="MainLabelStyle" TargetType="Label">
<Setter Property="BackgroundColor" Value="Black"/>
<Setter Property="TextColor" Value="White"/>
<Setter Property="Font" Value="35"/>
<Setter Property="YAlign" Value="Center"/>
<Setter Property="XAlign" Value="Center"/>
</Style>
</ResourceDictionary>
</ContentPage.Resources>
<Grid Padding="5,0" RowSpacing="1" BackgroundColor="Black" ColumnSpacing="1">
<Grid.BindingContext>
<local:MainViewModel />
</Grid.BindingContext>
<Grid.RowDefinitions>
<RowDefinition Height="*"/>
<RowDefinition Height="*"/>
<RowDefinition Height="*"/>
<RowDefinition Height="*"/>
<RowDefinition Height="*"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*" />
<ColumnDefinition Width="*" />
<ColumnDefinition Width="*" />
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<Label Grid.Row="1" Grid.Column="0" Grid.ColumnSpan="3"
Text="{Binding DisplayValue}" Style="{DynamicResource MainLabelStyle}" />
<Button Text="←" Grid.Row="1" Grid.Column="3" Command="{Binding BackspaceCommand}"
Style="{DynamicResource BackSpaceButtonStyle}" />
<Button Text="7" Grid.Row="3" Grid.Column="0" Command="{Binding NumberComamnd}"
CommandParameter="7" Style="{DynamicResource NumberStyle}"/>
<Button Text="8" Grid.Row="3" Grid.Column="1" Command="{Binding NumberComamnd}"
CommandParameter="8" Style="{DynamicResource NumberStyle}"/>
<Button Text="9" Grid.Row="3" Grid.Column="2" Command="{Binding NumberComamnd}"
CommandParameter="9" Style="{DynamicResource NumberStyle}"/>
<Button Text="4" Grid.Row="4" Grid.Column="0" Command="{Binding NumberComamnd}"
CommandParameter="4" Style="{DynamicResource NumberStyle}"/>
<Button Text="5" Grid.Row="4" Grid.Column="1" Command="{Binding NumberComamnd}"
CommandParameter="5" Style="{DynamicResource NumberStyle}"/>
<Button Text="6" Grid.Row="4" Grid.Column="2" Command="{Binding NumberComamnd}"
CommandParameter="6" Style="{DynamicResource NumberStyle}"/>
<Button Text="1" Grid.Row="5" Grid.Column="0" Command="{Binding NumberComamnd}"
CommandParameter="1" Style="{DynamicResource NumberStyle}"/>
<Button Text="2" Grid.Row="5" Grid.Column="1" Command="{Binding NumberComamnd}"
CommandParameter="2" Style="{DynamicResource NumberStyle}"/>
<Button Text="3" Grid.Row="5" Grid.Column="2" Command="{Binding NumberComamnd}"
CommandParameter="3" Style="{DynamicResource NumberStyle}"/>
<Button Text="0" Grid.Row="6" Grid.Column="0" Grid.ColumnSpan="3"
CommandParameter="0" Style="{DynamicResource NumberStyle}" Command="{Binding NumberComamnd}" />
<Button Text="." Grid.Row="6" Grid.Column="3" Command="{Binding AddPointCommand}"
Style="{DynamicResource OperationsStyle}"/>
<Button Text="/" Grid.Row="2" Grid.Column="2" Command="{Binding OperatorCommand}"
CommandParameter="/" Style="{DynamicResource OperationsStyle}"/>
<Button Text="x" Grid.Row="2" Grid.Column="3" Command="{Binding OperatorCommand}"
CommandParameter="x" Style="{DynamicResource OperationsStyle}" Font="25"/>
<Button Text="-" Grid.Row="3" Grid.Column="3" Command="{Binding OperatorCommand}"
CommandParameter="-" Style="{DynamicResource OperationsStyle}"/>
<Button Text="+" Grid.Row="4" Grid.Column="3" Command="{Binding OperatorCommand}"
CommandParameter="+" Style="{DynamicResource OperationsStyle}"/>
<Button Text="√" Grid.Row="2" Grid.Column="1" Command="{Binding OperatorCommand}"
CommandParameter="√" Style="{DynamicResource OperationsStyle}"/>
<Button Text="=" Grid.Row="5" Grid.Column="3" Command="{Binding CalculationCommand}"
Style="{DynamicResource OperationsStyle}"/>
<Button Text="C" Grid.Row="2" Grid.Column="0" Command="{Binding CleanCommand}"
Style="{DynamicResource CleanButtonStyle}"/>
</Grid>
</ContentPage>
I think my xmlns:local is messed up the class the xaml references is MainViewModel witch is in a folder in the project called Math and then sub folder within math called ViewModels
Any ideas on how to fix this issue?

Answer 1

The problem does not seem to be in your local namespace declaration but seems to be in you using properties which are marked as obsolete.
Have a look at this piece of your XAML, to which your error messages refer.
<Style x:Key="MainLabelStyle" TargetType="Label">
<Setter Property="BackgroundColor" Value="Black"/>
<Setter Property="TextColor" Value="White"/>
<Setter Property="Font" Value="35"/>
<Setter Property="YAlign" Value="Center"/>
<Setter Property="XAlign" Value="Center"/>
</Style>
If we lookup the YAlign and XAlign in the Xamarin Forms documentation, you'll see they are marked as obsolete. You should now use VerticalTextAlignment and HorizontalTextAlignment respectively.