Retrieving information from derived child object collections using LINQ - linq

Question

I have been trying to get a list of all Workflows that have Offices contained in a certain List by Office Id. I can easily get all of the Workflows that have SingleWorkflowSteps because they have only one Office, but have been unable to understand how I would successfully get those contained in a MultiWorkflowStep. All workflow steps have either a SingleWorkflowStep or a MultiWorkflowStep that contains two or more SingleWorkflowSteps. At the time I designed this, it seemed like a logical way to do this but atlas my LINQ-fu is not as good as I thought it was. Can someone please point me in the right directions. Code listed below:
var OfficesToFind = new List<int> (new int[] { 1,3,5,7,9,10,11,12} );
public class Workflow
{
public Workflow()
{
WorkflowSteps = new List<WorkflowStepBase>();
}
public int Id { get; set; }
public virtual ICollection<WorkflowStepBase> WorkflowSteps { get; set; }
}
public abstract class WorkflowStepBase
{
public int Id { get; set; }
public int StatusId { get; set; }
public virtual Workflow Workflow { get; set; }
public virtual Status Status { get; set; }
}
public class MultiWorkflowStep : WorkflowStepBase
{
public MultiWorkflowStep()
{
ChildSteps = new List<SingleWorkflowStep>();
}
public virtual ICollection<SingleWorkflowStep> ChildSteps { get; set; }
}
public class SingleWorkflowStep : WorkflowStepBase
{
public int? ParentStepId { get; set; }
public int OfficeId { get; set; }
public virtual MultiWorkflowStep ParentStep { get; set; }
public virtual Office Office { get; set; }
}
public class Office
{
public int Id { get; set; }
public string Name { get; set; }
}
public class WorkflowService : IWorkflowService<Workflow>
{
private readonly IRepository<Workflow> _workflowService;
private readonly IRepository<SingleWorkflowStep> _singleStepService;
private readonly IRepository<MultiWorkflowStep> _multiStepService;
public WorkflowService(IUnitOfWork uow)
{
_workflowService = uow.GetRepository<Workflow>();
_singleStepService = uow.GetRepository<SingleWorkflowStep>();
_multiStepSercice = uow.GetRepository<MultiWorkflowStep>();
}
// ~ ------- Other CRUD methods here -------- ~
public IEnumerable<Workflow> GetWorkflowFilter(List<int> statuses, List<int> offices...)
{
var query = _workflowService.GetIQueryable(); // returns an IQueryable of dbset
if(statuses.Any())
{
query = query.Where(q => statuses.Contains(q.StatusId));
}
if(offices.Any())
{
// Get all active single steps and the ones that contain the offices
singleSteps = _singleStepService
.Where(s => s.StatusId == (int)Enumerations.StepStatus.ACTIVE)
.Where(s => offices.Contains(s.OfficeId));
// Get all of the parent Workflows for the singleSteps
var workflows = singleSteps.Select(w => w.Workflow);
// Update the query with the limited scope
query = query.Where(q => q.Workflow.Contains(q));
}
return query.ToList();
}
}

Answer 1

OK, after a good night sleep, being all bright-eyed and bushy-tailed, I figured out my own problem. First the updated code was all wrong. Because each derived WorkflowStep has access to the Workflow and each MultiWorkflowStep contains a list of SingleWorkflowSteps - when I get the list of all SingleWorkflowSteps (which would include all from MultiWorkflowStep(s)), I simply needed to get a list of all of the parent Workflows of the SingleWorkflowSteps. Next I updated my query to limit the Workflows that were contained in the new Workflow list and here is the correct code for the GetWorkflowFilter method:
...
if(offices.Any())
{
// Get all active single steps and the ones that contain the offices
singleSteps = _singleStepService.Where(s => s.StatusId == (int)Enumerations.StepStatus.ACTIVE).Where(s => offices.Contains(s.OfficeId));
// Get all of the parent Workflows for the singleSteps
var workflows = singleSteps.Select(w => w.Workflow);
// Update the query with the limited scope
query = query.Where(q => q.Workflow.Contains(q));
}
return query.ToList();
}