IValueConverter's Convert method not invoking

Question

0.00/5 (No votes)

See more:

I have grid and i want to color foreground red if Qty < 0 .
I am not allow to add code at design time in xaml So i run time add

C#

Binding binding = new Binding("Qty") { Converter = new RedConverter() };
Style st = new Style(typeof(GridColumn));
st.Setters.Add(new Setter(Control.ForegroundProperty, binding));
_Left_Part_DE.Columns["Qty"].Style = st;

and my converter class is

C#

public class RedConverter : IValueConverter
    {
        public object Convert(object value, Type targetType,
            object parameter, CultureInfo culture)
        {
            return value.Convert_To_Number_DE<decimal>() < 0 ? Brushes.Red : Brushes.Black;
        }

        public object ConvertBack(object value, Type targetType,
            object parameter, CultureInfo culture)
        {
            throw new NotImplementedException();
        }
    }

problem is that it is not occurring any error nor invoking the Convert method
what is lacking

Posted 1-Aug-13 1:14am

kiranrahir

Updated 1-Aug-13 1:57am

v4

Add a Solution

2 solutions

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Irina Pykhova · Answer 1 · 2013-08-01T05:13:00

Solution 1

you set binding in the style setter for column. But according your question, you need it for individual cell, not for column. What is your _Left_Part_DE? If it has property like CellStyle, try to use it instead of Style (in such case Style target type should be changed as well).

C#

Binding binding = new Binding("Qty") { Converter = new RedConverter() };
Style st = new Style(typeof(CellContentPresenter));
st.Setters.Add(new Setter(Control.ForegroundProperty, binding));
_Left_Part_DE.Columns["Qty"].CellStyle = st;

Posted 1-Aug-13 5:13am

Irina Pykhova

Updated 2-Aug-13 23:08pm

v2

Comments

kiranrahir 2-Aug-13 8:15am

_Left_Part_DE is my DevExpress.XtraGrid grid and "Qty" is column.
I want to use Style.
if Qty < 0 than cell forecolor should be red. Can i do it with Style - IValueConverter?

Irina Pykhova 2-Aug-13 8:31am

in your case Style - is a column style. It is applied to the column as a single FrameworkElement, not to individual cells. Use CellStyle property. Here is DevExpress sample of cell appearance customization: http://documentation.devexpress.com/#WPF/CustomDocument6772. They use CellStyle property. In the sample they set it in xaml, you should do the same from code.

kiranrahir 3-Aug-13 1:05am

I want exactly that. I had read that artical, but problem is that my itemsouce is not fixed so
cant add this code

<dxg:gridcontrol.resources xmlns:dxg="#unknown">
<Style x:Key="customCellStyle"
BasedOn="{StaticResource {dxgt:GridRowThemeKey ResourceKey=CellStyle}}"
TargetType="dxg:CellContentPresenter">
<setter property="Background" value="{Binding Path=RowData.Row.UnitsOnOrder, Converter={local:IntToColorConverter}}"></setter>
</Style>
</dxg:gridcontrol.resources>

i want its behind c# code. How can i assign Style to cellstyle

Irina Pykhova 3-Aug-13 5:09am

Just rename style target type and property in your code.
I added code snippet to my answer above
And it doesn't make any sense whether your items source is fixed or no. This should work in any case both from xaml and from code

kiranrahir 3-Aug-13 6:05am

May you think that i m stupid but i am not seeing any Code Snippet.
in my code i add
xaml part

<dc:GridControl Name="Left_Part_DE" >
<dxg:GridControl.DetailDescriptor>
<dxg:DataControlDetailDescriptor Name="ctlDataControlDetailDescriptor" >
<dxg:DataControlDetailDescriptor.DataControl>
<dc:GridControl AutoPopulateColumns="True" Name="ctl_Child_Grid">
<dxg:GridControl.View>
<dxg:TableView ShowGroupPanel="False" AutoWidth="True" NavigationStyle="Row" />
</dxg:GridControl.View>
</dc:GridControl >
</dxg:DataControlDetailDescriptor.DataControl>
</dxg:DataControlDetailDescriptor>
</dxg:GridControl.DetailDescriptor>
<dxg:GridControl.View>
<dxg:TableView ShowGroupPanel="False" AutoWidth="True" NavigationStyle="Row" />
</dxg:GridControl.View>
</dc:GridControl>

c# part

Style _Style = new Style(typeof(CellContentPresenter));
Setter _Setter = new Setter();
_Setter.Property = CellContentPresenter.BackgroundProperty;
_Setter.Value = new Binding("RowData.Row.Qty") { Converter = new RedConverter() };
_Style.Setters.Add(_Setter);
_Left_Part_DE.Columns["Qty"].CellStyle = Style;

but problem is that no error occur nor event is invoking for background.
Am i missing any thing?

Irina Pykhova 3-Aug-13 6:39am

Looks Ok at first sight. You should debug this. There are a lot of possible problems. You might need different binding path. Or maybe you set style too late when all cells are already filled. Make sure that your code (where you set binding) is actually called. Set WPF Trace Settings to All (in VS Options), and look what you see in output window, maybe there are data binding errors.. If your data grid is editable, check what happens if you change cell value at runtime.
Or first check whether the style is applied at all - comment out converter in style setter, try to set red background without condition. Does it work?

kiranrahir 3-Aug-13 7:16am

i am new to wpf .
-> as per example of dev express i set binding path "RowData.Row.Qty".
if any other example is there than you can suggest me. May be i m wrong at that place but i do not know what to write

-> as you said i may assign style too late when all cells are already filled.
but just after assigning itemsource i set style.

_Left_Part_DE.ItemsSource = dtItem_Closing_Stock.DefaultView;
_Left_Part_DE.Columns["Qty"].CellStyle = Style;

-> i debug the code. and code assigns source and style both.

-> i enable trace but it didnt arice binding error in output

-> grid is only for display purpose it is not editable

-> i comment out condition in converter and return only red and put breakpoint at the Convert Method
:( but it is not invoked

Irina Pykhova 3-Aug-13 8:11am

hard case. I'm afraid that no one can tell you something for sure without debugging your code. Try to subscribe on AutoGeneratedColumns event and alter column properties in event handler:
http://documentation.devexpress.com/#WPF/DevExpressXpfGridDataControlBase_AutoGeneratedColumnstopic
There is no sample for this event, but the idea should be the same as in old event which has been replaced by this one: http://documentation.devexpress.com/#WPF/DevExpressXpfGridDataControlBase_ColumnsPopulatedtopic. I suggest you to try changing CellTemplate as well. At first, you can do very simple DataTemplate, something like red border and assign it to Column.CellTemplate property. If it works, you can make it more complicated with binding to your data and converter.

kiranrahir 5-Aug-13 1:12am

Hi thanks for your kind support :). But an internal error was there in our class i made new example and it works perfectaly :)

Irina Pykhova 3-Aug-13 6:44am

any chance that you need style for ctl_Child_Grid?

kiranrahir 3-Aug-13 7:17am

I do not need to style for ctl_Child_Grid

kiranrahir · Answer 2 · 2013-08-04T19:16:00

XML

<dx:gridcontrol name="ctl_Grid" height="900" width="900" xmlns:dx="#unknown">
            <dxg:gridcontrol.detaildescriptor xmlns:dxg="#unknown">
                <dxg:datacontroldetaildescriptor name="ctlDataControlDetailDescriptor">
                    <dxg:datacontroldetaildescriptor.datacontrol>
                        <dx:gridcontrol autopopulatecolumns="True" name="ctl_Child_Grid">
                            <dxg:gridcontrol.view>
                                <dxg:tableview showgrouppanel="False" autowidth="True" navigationstyle="Row" />
                            </dxg:gridcontrol.view>
                        </dx:gridcontrol>
                    </dxg:datacontroldetaildescriptor.datacontrol>
                </dxg:datacontroldetaildescriptor>
            </dxg:gridcontrol.detaildescriptor>
            <dxg:gridcontrol.view xmlns:dxg="#unknown">
                <dxg:tableview showgrouppanel="False" autowidth="True" navigationstyle="Row" />
            </dxg:gridcontrol.view>
        </dx:gridcontrol>

c# part

C#

Style _Style = new Style(typeof(CellContentPresenter)); 
Setter _Setter = new Setter(); _
Setter.Property = CellContentPresenter.BackgroundProperty; 
_Setter.Value = new Binding("RowData.Row.Qty") { Converter = new RedConverter() }; 
_Style.Setters.Add(_Setter); _
Left_Part_DE.Columns["Qty"].CellStyle = Style;