The Scenario
Currently I have a C# Silverlight Application That uses the domainservice class
and the ADO.Net Entity Framework to communicate with my database. I want to load a child window upon clicking a button with some data that I retrieve from a server-side query to the database.
The Process
The first part of this process involves two load
operations to load separate data from 2 tables. The next part of the process involves combining those lists of data to display in a listbox.
The Problem
The problem with this is that the first two asynchronous load
operations haven't returned the data by the time the section of code to combine these lists of data is reached, thus result in a null value exception.....
Initial Load
Operations To Get The Data:
public void LoadAudits(Guid jobID)
{
var context = new InmZenDomainContext();
var imageLoadOperation = context.Load(context.GetImageByIDQuery(jobID));
imageLoadOperation.Completed += (sender3, e3) =>
{
imageList = ((LoadOperation<InmZen.Web.Image>)sender3).Entities.ToList();
};
var auditLoadOperation = context.Load(context.GetAuditByJobIDQuery(jobID));
auditLoadOperation.Completed += (sender2, e2) =>
{
auditList = ((LoadOperation<Audit>)sender2).Entities.ToList();
};
}
I Then Want To Execute This Immediately:
IEnumerable<JobImageAudit> jobImageAuditList
= from a in auditList
join ai in imageList
on a.ImageID equals ai.ImageID
select new JobImageAudit
{
JobID = a.JobID,
ImageID = a.ImageID.Value,
CreatedBy = a.CreatedBy,
CreatedDate = a.CreatedDate,
Comment = a.Comment,
LowResUrl = ai.LowResUrl,
};
auditTrailList.ItemsSource = jobImageAuditList;
However I can't because the async calls haven't returned with the data yet...
Thus I have to do this (Perform the Load
Operations, Then Press A Button On The Child Window To Execute The List Concatenation
and binding):
private void LoadAuditsButton_Click(object sender, RoutedEventArgs e)
{
IEnumerable<JobImageAudit> jobImageAuditList
= from a in auditList
join ai in imageList
on a.ImageID equals ai.ImageID
select new JobImageAudit
{
JobID = a.JobID,
ImageID = a.ImageID.Value,
CreatedBy = a.CreatedBy,
CreatedDate = a.CreatedDate,
Comment = a.Comment,
LowResUrl = ai.LowResUrl,
};
auditTrailList.ItemsSource = jobImageAuditList;
}
Potential Ideas for Solutions:
Delay the child window displaying somehow?
Potentially use DomainDataSource
and the Activity Load control?!
Any thoughts, help, solutions, samples comments etc. greatly appreciated.
