DataSet vs DataTable

[Anders Eriksson]

I have a program that uses a DataGridView.

It will only show one table that consist of one column and any amounts
of rows.

Should I use a DataSet or is it OK to use the DataTable directly as
DataSource?

// Anders

 

[Anders Eriksson]

You can use a Datatable and bind it to a control directly. A Dataset is
a container for one or more Datatables.

OK, then it's easier to use a DataTable.

You can also use a List<T> and bind it to a control.

Hmmm, I have read somewhere that a list<T> has some problems when using
it as a binding source.

It's probably something I have misinterpreted....

Thank you for our answer!

// Anders

 

[Anders Eriksson]

[...]
Hmmm, I have read somewhere that a list<T> has some problems when using
it as a binding source.

It's probably something I have misinterpreted....

It depends on what behavior you expect. List<T> does not offer
notifications for changes, so it's not full-featured when used as a
binding source. There is a BindingList<T> that is better for that purpose.

Now when you mention it, this is what i read!

For many scenarios, the bound list isn't expected to change and a plain
List<T> is fine.

OK, The more you know the more choices you have to make...

Thank you very much!

// Anders

 

[Arne Vajhøj]

On 8/14/11 12:25 PM, Anders Eriksson wrote:
[...]
Hmmm, I have read somewhere that a list<T> has some problems when using
it as a binding source.

It's probably something I have misinterpreted....

It depends on what behavior you expect. List<T> does not offer
notifications for changes, so it's not full-featured when used as a
binding source. There is a BindingList<T> that is better for that
purpose.

Now when you mention it, this is what i read!

For many scenarios, the bound list isn't expected to change and a plain
List<T> is fine.

OK, The more you know the more choices you have to make...

Thank you very much!

But you can make the object a smart object in the List<T>, and you can
query for any object that is dirty by using Linq to determine if any
object in the List<T> is dirty.

After the binding of a List<T> and you need to change a property of the
object, you can do it off of the grid's index and address the object's
property directly.

<http://www.dailycoding.com/Posts/maintaining_dirty_and_new_state_of_objects.aspx>

If you send the List<T> to a Business or Data Access layer or you
persist data by other means, then you know which persist logic to use
for the object based on the object's state.

1) IsNew and IsDirty -- insert
2) !IsNew and IsDirty - update
3) IsDelete -- delete

Stuff like that I would expect the ORM to do without adding
user any code.

If I had to do myself I would not use the design in the link:
- require specific base class
- require code in each property set to mark it as dirty

Instead I would:
- require specific interface
- require properties to be virtual
- wrap the instances in a proxy

That is a more flexible design and mean writing a lot less code.

Arne

PS: I have an implementation using Castle if someone want to see
an example.