Design Question - DropDown Objects

[IgnyteSoftware]

I'm doing a Blazor app and have what surely is a simple CSLA design question. Basically I have a User class that can be assigned one or more JobTypes (which has a name and a couple of other properties I need). I initially thought I would add a property for JobTypes as a ReadOnlyBindingListBase collection but that doesn't really work as the list changes based on what is assigned by the admin. I didn't think it was appropriate to do a BusinessBase object that could be modified because there is another screen that a handles crud operations on Job Types (this via a DynamicList collection bound a to grid).

So my question is how should a scenario such as this be handled in CSLA where you have a list of items like JobTypes that won't change often but that will be assigned to a BusinessBase object like User object?

From a UI perspective it is just a grid with a UserName column and a Job Types column that contains a muti-select dropdown so the admin can pick one or more JobType objects. All possible JobTypes need to be bound to the dropdown so the user can select one and then whatever is selected must be bound to the User.JobTypes property. How are others designing CSLA objects with such a requirement?

[rockfordlhotka]

There's not one right answer.

If I understand you correctly, the JobTypes list can change, but changes very infrequently, and the changes are via an admin screen, not as part of someone modifying the User object.

What I normally do in cases like this is:

1. Create JobTypeEditList and JobTypeEdit types to support the admin screen (BusinessListBase/BusinessBase)
2. Create a UserEdit type to support the form where editing the User occurs; with a JobTypeId property in the UserEdit class
3. Create JobTypeList and JobTypeInfo types (ReadOnlyListBase/ReadOnlyBase), or just use a NameValueList, to support the combobox
4. Maybe create a unit of work type like UserEditGetter that gets the UserEdit and JobTypeList objects in a single call to the app server (though for just two types it probably isn't worth it - but for a big form with multiple objects and numerous combobox controls then a UOW type can be worth the effort)

[rockfordlhotka]

Actually I think I misread - you have a list of UserEdit objects right? So step 2 would be a UserEditList containing UserEdit objects, each with a JobTypeId property.

[IgnyteSoftware]

Yeah, I basically have a JobTypeEdit and a corresponding DynamicList which is used on a Blazor grid which allows the admin to add new job types if that is needed (rarely will be).

Then I have a UserEdit which is used on the User admin screen to manage the all the users which includes a column that somehow needs to let the user pick one or more JobTypes which would be bound to UserEdit.JobTypes. I started with a ReadOnlyListBase of job type objects (ReadOnlyJobType) but that didn't quite work. so UserEdit.JobTypes was a ReadOnlyListBase. For some reason when I turned off the readonly flag and modified the list the object was not marked as dirty. So even though I was able to achieve most of what I was wanting, binding didn't work correctly. When a user edited user row and added a new job type, IsDirty was still false.

So that is why I thought I would ask what others were doing. I assumed it was something to do with the ReadOnlyListBase that I had chosen.

[IgnyteSoftware]

I don't think I can add a JobTypeId property to the UserEdit because the control requires two binding sources of IEnumerable<T>. So I have to have something like this...

<DropDown DataSource= "@Cache.AllJobTypes" 
                     SelectedItemsDataSource = "@currentUser.JobTypes" ....

[rockfordlhotka]

The core question, in my mind, is whether the list of job types will vary depending on each specific UserEdit instance? Or it is a single list that is the same for all items in your datagrid?

[rockfordlhotka]

Two IEnumerable types?

Usually a combobox requires one IEnumerable and one singular field (int, string, etc) for the key. I'm pretty sure that's how the Blazor control works?

Or is it supporting a multi-select scenario where there's a list of selected items from the control?

[IgnyteSoftware]

Yes, one user may be assigned 1 job type and another may have 3. Those will be different based on the user (UserEdit). The control I'm using is a third-party Blazor control that allows you to select one or more items in the dropdown. So for example, I select my user on the grid and get the EditForm screen displays and the dropdown shows I currently have two job types assigned to me (ex: Teacher and Janitor), the dropdown shows that I can select all the other job types available at which point I can select more to add.

This third party Blazor control expects both data sources (the dropdown and the items selected) to support the IEnumerable<T> interface. I tried to be generic in describing the control but if you are interested, this is a multi-select dropdown control from DevExpress .. <DxTagbox> Blazor control.... I don't think this affects the design question though.