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Editorial Team
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Asked: 2026-05-12T00:23:47+00:00

I am doing the below test to try and learn more about LINQ to

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I am doing the below test to try and learn more about LINQ to SQL.

I have got an Activities table which contains an activityId, parentId, type.

The type is used as a discriminator value, to say whether it is an activity, task or project.

I have an Activity, Task and Project class that inherit from Activity, it seems wrong for Task to inherit from Project semantically but to reduce redundant data it seemed a better way to do it, I may either change the name of that class or separate them.

Activity class does not have a parentId property but the Task class will use the parentId as a projectId to associate to the Project class.

I have attached a screenshot of the tables and my dbml as well as a class diagram, you can see from the class diagram it is only a simpler implementation I am not having sub-activities, tasks across diff projects, etc. I am also ignoring the user side of this sytem because it is only a prototype.. so ignore the manager class and I wont be using roles.. I am only using hardcoded test users.

I have a list of things I wanted to ask about.
1. My tasks all require a projectId since this is the parentID from the activity class.. how is this setup to work with the Project class? as you can see there is no association between them at the moment.. should I be creating a property for Project? how does that work when ActivityId is potentially also the projectID when it comes to the Project class?

  1. You can see an ActivityTime class that should only be for tracking time spent on a task, you can see this can be associated to the UserActivity table but I am wondering how this is done only for Tasks and not for all Activities?

  2. You can also see a project activity, sorry this class should also be inheriting from the Activity class I missed this when uploading the image. This is for such things as a milestone where an activity with no related time or user should still have a related project.

Anyone got any ideas on what I am trying to achieve? am I going too far with all of this? Thanks for any help 🙂 Sorry if there is not enough detail I was trying to keep it brief without going into a full list of the business requirements I had in mind for this test system.

EDIT: Just stating the obvious I’m sure but please copy the image location to take a better look.

alt text http://img134.imageshack.us/img134/1199/tmss.jpg

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1 Answer

  1. Editorial Team

    I came up with a solution to this using the entity diagram for LINQ to SQL as shown above.

    Where I created a base activity abstract class that activity, task, project and project activity inherit from.

    Also the entity diagram seems to require you to add properties to inherited classes just to be able to use them for associations between classes. So in the end I did just that and made the original activityId from the base activity class a private property.

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