Binding binary field to ASP.NET DataGrid Causes Error

Question

I have a dataset with one of it's fields named "Reviewed".

This dataset is popualted and below picture show it's data: enter image description here

Now Im trying to show this dataset inside a DataGrid :

<ASP:TemplateColumn HeaderText="Reviewed" HeaderStyle-HorizontalAlign="center" HeaderStyle-Wrap="True">
                                    <ItemStyle Wrap="false" HorizontalAlign="center" />
                                            <ItemTemplate>
                                                <ASP:Checkbox  Checked='<%# DataBinder.Eval(Container.DataItem, "Reviewed") %>' runat="server" ID="Label22" />
                                            </ItemTemplate>
                                            <EditItemTemplate>
                                                <Asp:Checkbox id="Textbox5" width="40" Checked='<%# DataBinder.Eval(Container.DataItem, "Reviewed") %>' runat="server" />
                                            </EditItemTemplate>
        </ASP:TemplateColumn>

I get the following Error:

Exception Details: System.InvalidCastException: Cast from type 'DBNull' to type 'Boolean' is not valid.

What I am doing wrong? Question is where DBNull comes from?

================================

Update:

Thanks for the nice answers. My main point of confusion was "STUPID" XML visualizer was wrongly showing Reviewed field as checked(as you see in the picture above). I checked the values in the dataset itself and realized all are indeed DBNUll.

as the error message says - you can't convert dbNull to a boolean value. you may have a look to this blog which presents a solution to this or have a look at my answer — Pilgerstorfer Franz
– Pilgerstorfer Franz, Commented Jul 18, 2013 at 14:08

Ehsan · Accepted Answer · 2013-07-18 14:17:52Z

1

It means that some of your data coming from database is null. You need to check for that before assigning.You might want to assign a default value Like.

iif((DataBinder.Eval(Container.DataItem, "Reviewed") is DbNull.Value),false, DataBinder.Eval(Container.DataItem, "Reviewed")))

You can also create a method that checks for both DBNULL and null values and returns you the appropriate value. like (it may have syntax error that you can correct)

<Asp:Checkbox id="Textbox5" width="40" Checked='<%# YourMethod(Eval("Reviewed")) %>' runat="server" />

edited Jul 18, 2013 at 14:17

answered Jul 18, 2013 at 14:06

Ehsan

32.9k6 gold badges61 silver badges66 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

S Nash Over a year ago

See the picture I posted. All of data are populated.

Ehsan Over a year ago

Execute your query in the database and you will find out that some of the row is containing the null value which is causing error

Pilgerstorfer Franz · Accepted Answer · 2013-07-18 14:10:05Z

1

Try to change your markup code to this code.

<asp:Checkbox 
  Checked='<%# (Eval("reviewed")==DBNull.Value ? false : Eval("reviewed"))%>' 
  runat="server" ID="Label22" />

So instead of binding a nullValue to boolean property you assign false if there is DBNull. Credits go to limno

answered Jul 18, 2013 at 14:10

Pilgerstorfer Franz

8,3473 gold badges46 silver badges56 bronze badges

1 Comment

Pilgerstorfer Franz Over a year ago

ah - noted it right now - but as @ehsan ullah provided a working example I will not adapt my example so others have a working example in c# too

Collectives™ on Stack Overflow

Binding binary field to ASP.NET DataGrid Causes Error

2 Answers 2

2 Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related