WPF validation WITHOUT object in datacontext

This one is driving me crazy:-)

Lets say I have some test xaml code:

    <Window x:Class="ProWPFInCSharpyTestProject.ValidationTest"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="ValidationTest" Height="300" Width="300">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition />
            <RowDefinition />
            <RowDefinition />
            <RowDefinition />
        </Grid.RowDefinitions>

        <TextBox Margin="10" Name="someTextBox" VerticalAlignment="Top" Text="" />
        <TextBox Grid.Row="1" Margin="10" Name="SomeTextBox2" VerticalAlignment="Top" />
        <TextBlock Grid.Row="2" Margin="10" Name="errorMessageTextBlock"  />
        <Button Content="Click Me" Grid.Row="3" Margin="10" VerticalAlignment="Top" />
    </Grid>
</Window>

Now, I have no object bound to it, because it will collect data from the form and throw it in the database. But now I want to validate if the fields are empty when the button is clicked and show an err开发者_C百科or message. Almost every single tutorial I have looked at has an object bound to the grid but this is not relevant to me.

Why can't this be more like asp.net? Just put a validator with a validator group. It would things so much less cryptic and complex than it is now.

---

Sorry man, but you're doing WPF not ASP.NET. I understand that WPF can be frustrating but is not a good idea to bend a technology to your old habits. Having said that, You're talking about gathering the data entered then pass it to the database. One way to do it in WPF is using a ViewModel or any object to act as some kind of container. The WPF binding stuff will tell you if something went wrong. Then you can pass/translate your objects to the Data Layer/ORM and then lastly hit the database.

Maybe Kent approach works, but not in complex scenarios.

---

OK, assuming you really don't want a model:

    <TextBox Margin="10" Name="someTextBox" VerticalAlignment="Top" Text="" />
    <TextBox Grid.Row="1" Margin="10" Name="SomeTextBox2" VerticalAlignment="Top" />
    <TextBlock Grid.Row="2" Margin="10" Name="errorMessageTextBlock"  />
    <Button Name="button" Content="Click Me" Grid.Row="3" Margin="10" VerticalAlignment="Top" />

Then in the code behind:

button.Click += delegate
{
    if (someTextBox.Text == "" && someTextBox2.Text == "")
    {
        MessageBox.Show("Error!");
    }
    else
    {
        DoSomethingCool();
    }
};

As a hacky way to use the validation infrastructure without defining your own model, you could do this:

<TextBox>
    <TextBox.Text>
        <Binding Path="Tag" RelativeSource="{RelativeSource Self}">
            <Binding.ValidationRules>
                <!-- whatever rules you want here -->
            </Binding.ValidationRules>
        </Binding>
    </TextBox.Text>
</TextBox>

This hijacks the TextBox.Tag property as a place to store the bound data, which enables you to use Binding.ValidationRules.

But you're really resisting one of WPF's strongest attractions by not using data binding.

The clean way to do this is to define a model, bind the view to that model, and implement IDataErrorInfo in your model if you want validation.