RIA Services - Pagination

Question

I am testing out RIA services. I put together a RIA Services library and built a custom DomainService (i.e. not an Entity Framework Domain Service). I am accessing the library from a Silverlight app and all is working as expected. I can call the RIA service functions and get the results.

My issue is with pagination. I cannot find anywhere a description of using pagination on a RIA service that uses custom domainServices. My RIA Service is accessing a specialized DAL for access to data (and is not compatible with the Entity Framework). What I have found was an indication to pass the pagination parameters (i.e. page, page size) to a RIA Service function. So I have done just that - created a RIA service function that takes additional parameters for Page [index] and Page size. I am testing this in Silverlight using a DataGrid and a DataPager. The RIA service with the pagination parameters is called (and returns data) and the DataGrid is populated. The problem I'm having is when I go to another page. What is occurring is the RIA service is called twice. The first time with the proper params (i.e. correct page index) then again with a page index of zero). I.e. always resets to first page. I don't understand why this is occurring; I believe I put everything together properly (hopefully). The following is the XAML script:

<riaControls:DomainDataSource 
    Name="ddsScheduleTemplates"                         
    LoadSize="20" 
    QueryName="GetPagedScheduleTemplates"
    AutoLoad="True"
>

    <riaControls:DomainDataSource.DomainContext>
        <ds:ScheduleEngineDomainContext/>
    </riaControls:DomainDataSource.DomainContext>

    <riaControls:DomainDataSource.QueryParameters>
        <riaControls:Parameter ParameterName="UserLogonName" Value="admin" />
        <riaControls:Parameter ParameterName="UserPassword" Value="admin" />
        <riaControls:Parameter ParameterName="Page" Value="{Binding ElementName=dpScheduleTemplates, Path=PageIndex}" />
        <riaControls:Parameter ParameterName="PageSize" Value="{Binding ElementName=dpScheduleTemplates, Path=PageSize}" />
    </riaControls:DomainDataSource.QueryParameters>

</riaControls:DomainDataSource>

<StackPanel>

    <dg:DataGrid 
        Name="ScheduleTemplatesGrid" 
        MinHeight="100" 
        MaxHeight="300"
        IsReadOnly="True" 
        ItemsSource="{Binding ElementName=ddsScheduleTemplates, Path=Data}"
    />

    <dg:DataPager 
        x:Name="dpScheduleTemplates" 
        PageSize="10"
        Source="{Binding ElementName=ddsScheduleTemplates, Path=Data}"
        PageIndexChanged="dpScheduleTemplates_PageIndexChanged" 
    />

</StackPanel>

I have modified the above script to call the general loading function (GetPagedScheduleTemplates - returns all records) and adjusted the QueryParameters list for the function. The DataGrid loads properly - and pagination works properly.

This confused me - it sort of looked like the DataPager required all data to be loaded in order for it to work properly - but I did a test where I loaded all data on a paged request operation; (i.e. pagination properties setup and calling pagination version of RIA service function) but DataGrid still resets.

Note: I had read that the DataPager requires the return list to be ordered - so I did so - but did not affect operation - paging always reset to page 1 - the following is the return list from the RIA service function newList.ToArray().AsQueryable().OrderBy(x=>x.ScheduleTemplateID)

So; my question is - has anyone seen this behavior - or am I making a horrendous mistake - if so what am I doing wrong?

Peter

Peter Peter · Accepted Answer · 2010-12-20T13:43:27

Once I integrated the Legecay DAL library I mentioned above all was working properly. Review the library - it is easy to use (but there is some reading/review to get up to speed with it). Also make sure your RIA service is properly configured for pagination. From what I have read and found - setting a page size in the pager and domain data source is required for proper operation. The ria service call also requires a count operation (for the specific entity object) also that return the MAX record count (if this is not done then things like you mention may occur -- the domain data source does not know the total records to paginate through -so it may just go the beginning because it does not have enough info -- this is usally apparent because the pager will not show the proper max page count or will show 1 or zero for the max page).

Peter

RIA Services - Pagination

5 Answers