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.
