PropertyGridSpinEditor and null value

[Joe]

Hi, 

I'm currently populating the property grid using a RadPropertyStore.  One of my object's properties is a nullable Int32 field (Int32?) and I need to allow the user to empty out the PropertyGridSpinEditor cell.  Unfortunately, when the data cell is cleared out, it automatically gets set to a value of 0 instead of empty/null.

How can I allow the user to clear out the data and have null be considered a valid value?

Thanks,

Joe

PS.  See attached screenshot for current behavior.

[Dess | Tech Support Engineer, Principal]

Hello Joe,

Thank you for writing.

PropertyGridSpinEditor expects a valid numeric value. When its value is cleared, 0 is set. In order to deal with this undesired behavior, you can use the ItemFormatting event and hide the text according to your criteria by setting the PropertyGridItemElement.ValueElement.DrawText property to false. Thus, 0 value will not be displayed:

private void radPropertyGrid1_ItemFormatting(object sender, PropertyGridItemFormattingEventArgs e)
{
    PropertyGridItemElement el = e.VisualElement as PropertyGridItemElement;
    if (el != null)
    {
        if (e.Item.Label == "Integer" && el.ValueElement.Text=="0")
        {
            el.ValueElement.DrawText = false;
        }
        else
        {
            el.ValueElement.DrawText = true;
        }
    }
}

An alternative solution is to implement a custom editor which will cover your requirement. Please refer to Using custom editor help article.

I hope this information helps. Should you have further questions I would be glad to help.

 

Regards,
Dess
Telerik

[Joe]

Thanks for the reply, Dess.

Unfortunately, just hiding the text won't be enough as I need to distinguish between the user typing in 0 and the user clearing the value (i.e. null).

I guess I'll have to look into a custom editor.

Regards,

Joe

[Dess | Tech Support Engineer, Principal]

Hello Joe,

Thank you for writing back.

I have prepared a sample code snippet demonstrating how you can detect whether the value is cleared or the it is set to 0:

public Form1()
{
    InitializeComponent();

    PropertyStoreItem intItem = new PropertyStoreItem(typeof(Int32?), "Integer", 2);
    PropertyStoreItem floatItem = new PropertyStoreItem(typeof(float), "Float", 1f, "Property storing a floating point value.");
    PropertyStoreItem stringItem = new PropertyStoreItem(typeof(string), "String", "telerik", "Property storing a string value", "Telerik");

    RadPropertyStore store = new RadPropertyStore();
    store.Add(intItem);
    store.Add(floatItem);
    store.Add(stringItem);

    this.radPropertyGrid1.SelectedObject = store;
    this.radPropertyGrid1.EditorInitialized += radPropertyGrid1_EditorInitialized;
}

private void radPropertyGrid1_EditorInitialized(object sender, PropertyGridItemEditorInitializedEventArgs e)
{
    PropertyGridSpinEditor spinEditor = e.Editor as PropertyGridSpinEditor;
    if (spinEditor != null)
    {
        BaseSpinEditorElement el = spinEditor.EditorElement as BaseSpinEditorElement;
        el.ValueChanged -= el_ValueChanged;
        el.ValueChanged += el_ValueChanged;
        el.KeyUp += el_KeyUp;
    }
}

private void el_KeyUp(object sender, KeyEventArgs e)
{
    BaseSpinEditorElement el = sender as BaseSpinEditorElement;
    isCleared = false;
    if (el != null && el.Text == string.Empty)
    {
        isCleared = true;
    }
    else
    {
        isCleared = false;
    }
}

bool isCleared = false;

private void el_ValueChanged(object sender, EventArgs e)
{
    BaseSpinEditorElement el = sender as BaseSpinEditorElement;
    isCleared = false;
    if (el != null && el.Text == string.Empty)
    {
        isCleared = true;
    }
}

private void radPropertyGrid1_ItemFormatting(object sender, PropertyGridItemFormattingEventArgs e)
{
    PropertyGridItemElement el = e.VisualElement as PropertyGridItemElement;
    if (el != null)
    {
        if (e.Item.Label == "Integer" && el.ValueElement.Text == "0" && isCleared)
        {
            el.ValueElement.DrawText = false;
        }
        else
        {
            el.ValueElement.DrawText = true;
        }
    }
}

Note that this is just a sample approach and it may not cover all possible cases. Feel free to modify it in a way which suits your requirement best. 

I hope this information helps. If you have any additional questions, please let me know.

Regards,
Dess
Telerik

[Joe]

Thank you very much for the example, Dess - it's really appreciated.

I'm actually doing something very similar to suit it to my needs.

Regards,

Joe