C# WPF binding to method with ObjectDataProvider

Question

I have a strange behaviour using ObjectDataProvider. I need to bind a TextBlock with ToString method but, when I enter in method my properties are wrong.

This is my simple ObjectDataProvider:

<Window.Resources>
    <ObjectDataProvider x:Key="ToString" MethodName="ToString" ObjectType="{x:Type entities:Season}" />
</Window.Resources>

And this is my ListView:

<ListView Grid.Row="2" Name="lvSeasons" HorizontalContentAlignment="Stretch">
    <ListView.ItemTemplate>
        <DataTemplate>
            <Grid>
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="*" />
                    <ColumnDefinition Width="30" />
                </Grid.ColumnDefinitions>

                <TextBlock Grid.Column="0" Text="{Binding Source={StaticResource ToString}}" VerticalAlignment="Center" />
                <Button Grid.Column="1" VerticalAlignment="Center" Background="Transparent" BorderBrush="Transparent" Click="btDeleteSeason_Click">
                    <TextBlock FontFamily="{StaticResource FontAwesome}" Text="&#xf1f8;" FontSize="20" Foreground="Red" HorizontalAlignment="Center" />
                </Button>
            </Grid>
        </DataTemplate>
    </ListView.ItemTemplate>
</ListView>

My method simply concat two properties:

public override string ToString()
{
    return StartYear + "/" + EndYear;
}

In debug I can see that start and end year are always 0. If I bind my TextBlock using {Binding StartYear} it's correct and value is 2019.

Where can the problem be?

Well, why do you need to get a string using this way? You can use it in binding directly — Pavel Anikhouski, Nov 11 '19 at 15:28

Clemens · Accepted Answer · 2019-11-11T15:35:08.850

1

You do not need an ObjectDataProvider. Just write

<TextBlock Text="{Binding}" ... />

WPF will call the ToString method by default.

You do not even need to override ToString when you use a MultiBinding with an appropriate StringFormat:

<TextBlock ...>
    <TextBlock.Text>
        <MultiBinding StringFormat="{}{0}/{1}">
            <Binding Path="StartYear "/>
            <Binding Path="EndYear "/>
        </MultiBinding>
    </TextBlock.Text>
</TextBlock>

edited Nov 11 '19 at 15:35

answered Nov 11 '19 at 15:28

Clemens

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Thanks! It works fine, but where is the problem with my code? Why start and end year are 0? – erikscandola Nov 11 '19 at 15:48
The ObjectDataProvider doesn't know the item instance. It creates its own Season instance because you have set the ObjectType property. – Clemens Nov 11 '19 at 15:49
Ok. And how can I use my binding instances? – erikscandola Nov 11 '19 at 16:24
Like [this](https://stackoverflow.com/q/6585303/1136211) perhaps. – Clemens Nov 11 '19 at 17:35
Also with `DataTemplate.Resources` it doesn't work. Same problem. – erikscandola Nov 12 '19 at 08:27
I have always Start and End year set to 0. I want to undestand how `ObjectDataProvider` works. If I try to call a method in my window it doesn't fire, if I call method in my entity then the entity is an "empty" instance. – erikscandola Nov 12 '19 at 08:44

C# WPF binding to method with ObjectDataProvider

1 Answers1