Related Object Filtering

 

Excellent! Thank you. This is just what I've been looking for. Your posts have been very helpful.

 

Darren

 

Thanks for you reply. I think I have a better understanding of how it works now.

 

In Response to

 

"I'm sort of surprised that your query at the top level has to do anything more than exclude Inactive Divisions"

 

This all came about because I'm using the DevExpress Grid. If you're famaliar with this grid it is pretty powerful and flexible when working with related data. So, when I get an Active list of Divisions the grid recognizes that there are child relationships with the Division->Departments->Employees and will automatically create views for these records unless the "ShowDetails" properties are turned off. In my case I was using the Grid to create a "Tree" like effect that would show the Divisions down through Employees. Because the Grid is capable of displaying these records and relationships like this I wanted to do only one query against the objects and have only one bindable datasource. Of course I was trying to filter all the records to only active from the top down based on how I thought the quering worked. I could have queried each level seperately but the DevExpress grid can only bind to one source. You can have multiple members, that each have a different view, but the views can not have multiple binding sources (as far as I know they can't). So is it possible to do three EntityLists and join them into a single BindingSource? I don't know.

 

Based on you last statement

 

"Just understand that a query with subqueries still only filters the target entity: it doesn't do anything to that entity's children or other descendants, other than look at them to decide how to filter the parent list."

 

Ahh. Lights flickering. This explains the results I was getting. These subquery filters could determine what parent records I get back but CAN NOT filter the child records in any way. Glad to know how this really works. I think the "immortalize" strategy you talked about is what I will implement in the final run as this is a common view of the data that we see in several of our applications.

 

Last thing. I still had a couple of questions that maybe you can help me with. It would also be helpful to know how to take the records from the EntityList and work with the records as their original objects.

 

Otherwise, how do you convert the EntityList of Divisions to an actual Division object in code? As an example, how could I loop through the EntityList, casting the objects to the type they are, and then get to their related objects? If what I'm proposing is not recommended do you have an alternative? I can use the BindingSource to get the Current record and cast it to my object but I can't do the same with an EntityList. I figure there's got to be a way to get there but I haven't found it.

 

Thanks again for your help.

 

Darren

 

 

AddClause(EntityColumn pEntityColumn, EntityQueryOp pOperator, object pValue)

 

I've tested it both ways, using the parameter as string and an object, and either way still get the same results. I don't see anything wrong with the query compared to all the examples I've seen. It just doesn't work. What could cause this? Are there any alternatives?

 

I tried using a Predicate but I don't know how to use a Predicate on a child related object coming from the parent, when using the EntityList.ListManager. It would also be helpful to know how to take the records from the EntityList and work with the records as their original objects. Otherwise, how do you convert the EntityList of Divisions to an actual Division object? These things are probably simple to do but without any example code it isn't obvious to me how to do this. I have to get this thing working by tommorrow. Other than properly filtered lists I've got most of it working. All the queries I've done that work on the Parent level seem to work fine, so does sorting, and pass-thru queries. I'm missing something but I can't see what it is.

 

Darren

 

 

    public static EntityQuery GetDivisionAndChildrenByStatus(string status) {

      object mystatus = (object) status;

      EntityQuery query = new EntityQuery (typeof(Division));

      query.AddClause(Division.RecordStatusEntityColumn, EntityQueryOp.EQ, mystatus);
      query.AddOrderBy(Division.OrderEntityColumn, System.ComponentModel.ListSortDirection.Ascending);

      EntitySubquery aSubQuery = query.AddSubquery(EntityRelations.Division_Department);
      aSubQuery.AddClause(Department.RecordStatusEntityColumn, EntityQueryOp.EQ, mystatus);
     return query;
    }

 

I'm using the DevExpress grid with two views. It shows the proper records and relationships so that leads me to believe that I have the objects setup correctly, but I still get Inactive Departments with my Active Divisions. I don't understand how the code above can accurately return only the Active Divisions but not the correct Departments. I'm really under the gun here to get this completed but I have more similar things to do like this and it's not working. So, please help?

 

Darren

 

Darren

 

Division

  -> Department

         -> Employee

 

All three types of records use a RecordStatus field to determine whether they are still Active or Inactive. I created a RdbQuery in the Division to return only the Active Divisions. However, when I check the Department these objects still contain Inactive records, and the Departments have Inactive Employees. Here is my code: