FilterDescriptor returns null

11-06-2009 2:46 PM |

Hi all,

I have a ComboBox with three options that defines which operator should be used with a FilterDescriptor. That FilterDescriptor is linked to a DatePicker. I'm trying to do that in code-behind, but with any luck so far. 

In my XAML file I have the following code:

<riaControls:DomainDataSource x:Name="dds" AutoLoad="True" QueryName="Query" LoadSize="20">

                        <riaControls:DomainDataSource.FilterDescriptors>
                            <riaData:FilterDescriptorCollection>

                               <riaData:FilterDescriptor x:Name="filter1" PropertyPath="Date" >
                                    <riaData:ControlParameter ControlName="dtpDate" RefreshEventName="SelectedDateChanged" />
                                </riaData:FilterDescriptor>

                            </riaData:FilterDescriptorCollection>
                        </riaControls:DomainDataSource.FilterDescriptors>

</riaControls:DomainDataSource>

<!-- Filter: dates -->
<TextBlock Text="Date: " />
<ComboBox x:Name="cmbDate" DropDownClosed="cmbDate_DropDownClosed">
   <ComboBox.Items>
      <ComboBoxItem Content="All dates" IsSelected="True"/>
      <ComboBoxItem Content="Equal to"/>
      <ComboBoxItem Content="Since"/>
      <ComboBoxItem Content="Until"/>
   </ComboBox.Items>
</ComboBox>
<controls:DatePicker Name="dtpDate" />

I am trying to set the Operator for the filter1 FilterDescriptor on the DropDownClosed Event as follows:

            int idx = cmbDate.SelectedIndex;

            if (idx == 1) // Equal to option
                filter1.Operator = FilterOperator.IsEqualTo;
           
            if (idx == 2) // Since option
                filter1.Operator = FilterOperator.IsGreaterThanOrEqualTo;

            if (idx == 3) // Until option
                filter1.Operator = FilterOperator.IsLessThanOrEqualTo;

The lines above are short versions, but I think they illustrate what I'm trying to do.

filter1 results NULL whatever I do. I've tried other approaches but with no success. Can anyone help me with this? I don't even know if this is the best way to do what I want. I'm open to suggestions.

Thanks in advance.

Re: FilterDescriptor returns null

11-07-2009 5:08 AM |

 Have you tried to refresh your DomainDataSource after you've set the Filter Descriptor?

Re: FilterDescriptor returns null

11-09-2009 6:12 AM |

Hello Ardman, can you explain better what you mean. I'm sorry but I'm pretty new to this Silverlight and RIA services world... :)

Re: Re: FilterDescriptor returns null

11-09-2009 6:18 AM |

Certainly, when you change the Filter operator, clear the data from the DomainDataSource and then call the Load method to refresh the data.

Re: Re: Re: FilterDescriptor returns null

11-09-2009 6:55 AM |

Ok! :) I did it, but it results the same. I thought that when we referenced filter1 it would be recognized as the filter1 from the XAML file and all we had to do was changing its OPERATOR property, but it isn't recognized as being that object. When filter1.Operator line is executed returns 'Object reference not set to an instance of an object'...

Re: Re: Re: Re: FilterDescriptor returns null

11-09-2009 7:03 AM |

I'm not sure if this will work, but if you wanted to get the Filter from the DomainDataSource, you could try:

FilterDescriptor filterDesc = this.FindName("filter1") asFilterDescriptor;

filterDesc.Operator = FilterOperator.IsLessThanOrEqualTo;

But, I'm not sure this will work.

Re: Re: Re: Re: Re: FilterDescriptor returns null

11-09-2009 7:36 AM |

It didn't work. :( Thanks anyway Ardman. :) I am still trying to discover how to do this. If you have any other ideas I'll be much appreciated. :) Cheers

Re: Re: Re: Re: Re: Re: FilterDescriptor returns null

11-09-2009 7:36 AM |

If you remove the Filter Descpritor from the XAML and set it in the code only, does this work?