HowTo use a gridView in WinForms with an objectdatasource with full support of edit, add, delete??

Hi Bob:
1) Drop a DataGridView on a form
Done.
2) Drop a BindingSource on a form
Created by the obectdatasource
3) Create a Datasource for the BindingSource
?? The datasource is a List<class> function (Or the objectdatasource??? HOW???)
4) Bind the DataGridView to the BindingSource:  DataSource + DataMember
?? Done. Maybe its not clear what you mean with:"DataSource + DataMember" Found no datamember!
5) Use the generated TableAdapter to fill the DataSet defined in step #3.
?? The TableAdapter is never created.
This is the part which holds the update,add,insert procs WHEN using a web app (aspx form file)
This is what I miss.

What you describe is what happens when creating a web app (using aspx page with gridview).

WHAT I have done:
1) created a winform for a win app
2) created a datagridview
3) created a class with its properties which are for the gridview
4) created an objectdatasource from this class
5) the datagridview created a bindingsource from the dataobjectsource
7) I created a function which returns a list of <class> objects.
8) on winform constructor I assigned the gridview datasource the mentioned list<class> function
9) the data are listet correctly

There is NO tableadapter.
No chance for add,apdate,delete!

What have I done wrong?
What should I do to get my add, insert, delete?

Best
Juergen

What I tried to describe to you was a way to create a data source easily for the DataGridView that can be accomplished through the designer.  You would get a TableAdapter, with the ability to select, insert, update, and delete data from a DataTable.  Is there a reason that you need an ObjectDataSource?  

Bob

Hi Bob!

"...Is there a reason that you need an ObjectDataSource?..."
YES!
From my initial post: "This is a test project to learn howto use the objectdatasource"

Best
Juergen

How are you using the ObjectDataSource from a WinForms application?   It is an ASP.NET control, and I didn't think that it could be used outside of that environment.

Bob

Hi Bob,
from the datasources explorer create a new objectdatasource from a class.
The class propperties are to be used (displayed).

Drop a gridview on a winform.
From the small arrow on the upper right of the gridview (just don'tr know how it is called in english) select the objectdatasource.
This creates a myClassBindingSource
(Shortcut is to drag and drop the objectdatasource from the datasource explorer onto the  winform)

write a class list like:
    public static BindingList<myClass> getAllMyClass() {
      BindingList<myClass> list = new BindingList<myClass>();
      using(SqlConnection connection = new SqlConnection(myApp.Properties.Settings.Default.myAppConnectionString)) {
        using(SqlCommand command = new SqlCommand("[adb].getAllData, connection)) {
          command.CommandType = CommandType.StoredProcedure;
          connection.Open();
          using(SqlDataReader reader = command.ExecuteReader()) {
            while(reader.Read()) {
              WebLogon temp = new myClass(
                (string)reader["data1"],
                (string)reader["data1´2"],
                reader["data3"] is DBNull?null:(string)reader["data3"],
                (DateTime)reader["data4"],
                reader["data5"] is DBNull ? (DateTime?)null : (DateTime?)reader["data5"]
              );
              list.Add(temp);
            }
          }
          return list;
        }
      }
    }

you could also try:
 public static List<myClass> getAllMyClass() {
instead of
 public static BindingList<myClass> getAllMyClass() {
 
List<> works fine too.  

In the main form constructor:
myClassBindingSource.DataSource = BusinessObjects.getAllMyClass();

Now all data are shown in the grid.

Here I am stuck.
I still have no idea how to implement create,delete, update.

Any idea Bob?

Juergen

1) >>From the small arrow on the upper right of the gridview
SmartTag

2) I don't use the wizards, so I didn't think that was possible.

3) Are you selecting from a table with a primary key set?

Bob

Hi Bob,
ad 2) I tried it with and without the wizard: no difference in my goal of edit,delete,create

ad 3) The Table?? I handle an object, so that should not make a difference.
But YES, the example table in the background has a key set.

Any ideas how to get edit,delete,create with an objectdatasource to work?
i.e. here with a datagridview

Best
Juergen

Juergen,

Have you seen this walk-through from Microsoft?

Walkthrough: Connecting to Data in Objects  
http://msdn2.microsoft.com/en-us/library/ms171892(VS.80).aspx

The article talks about creating a TableAdapter, which should help you with your CRUD functionality.

Bob

Hello Bob,
I haven't read the article.

But a first glance shows that it does what I do so far. It just puts the List<> inside the class.
And sorting.

The rest is a walkthru meant exactly what the word means.
Not ver eficient, when a db is in the background as the factory for the class.

And it simply shows no way, when I change in a dataViewGrid a value howto intercept an edit,create,delete with something like a pointer to the regarding datarow set, so I can pick up the "key" value or something like that and all the rest for create,update,delete.

The sorting (order) shown is not of much interest, as the db in the background could easily be sortet by the "order by" statement.

The Tableadapter discussed shows how to fill the Objects. I do that handcoded.
The oblects are NOT in a DB-table!
If so there is no need of an object.
They are either assembled maybe over several tables with additional attributes for the object or pure objects.
But what about unconventional databases: simple text, xml, ...

What I still will try on your hint: Take any table table as a dummy to create a tableadapter and then use the update,create,... to intercept them and use it "my way".
A few tries didn't get me further.
But I have to stop here and as I have to do my usual work....

So where we are?
I feel still asking: How can I adapt create, edit, delete in an winapp with a datagridview to the underlying objectdatasource?

Best
Juergen

Juergen,

Since you created code to build a list of classes, then it should be fairly simple to create more code for the insert, update and delete functionality.  I mentioned the TableAdapter because it looked like you were using a database, like SQL Server, with a stored procedure, to build the class list.

Bob

Hello Bob,
at time I use a SQL DB with logon data. Simple and straightforward.

Later it will be some measurement data colllected from several sources.
They are in a Grid to inspect and change them b4 saving them to a DB.

But essentially I look for a general purpose solution ( to learn now and use it later) where I can handle the objectdatasource as a usual sq db source. The main obstacle at time is the update,edit,create.

I look for a solution how to implement a class as an object database source so I can use it no matter what kin of background data there are.

I prefer the OO access as it gives me more freedom.

But I still need to test the approach to create a dummy tableadapter for a sql DB which I than "switch" to the objectdatasurce.

Best
Juergen

Juergen,

Try this:

1) Delete -- keep track of which records need to deleted from the source, and use this to remove from the list:

        myClassBindingSource.List.Remove(object)
        myClassBindingSource.List.RemoveAt(index)

2) Update -- update the values in the controls bound to myClassBindingSource.

3) Insert -- add a new 'myClass' instance to the list.

4) When you need to save the changes, loop through the binding source list, and get 'myClass' instances, and perform whatever action you need to update the datasource:

    foreach (myClass c in myClassBindingSource.List)
    {
    }

Bob

Bob,
ur suggestion:
        myClassBindingSource.List.Remove(object)
        myClassBindingSource.List.RemoveAt(index)
lacks that NOTHING happens when I delete,edit,create on the datagrid.
So I can't pick up the index of the gridview, use it to look for a "key" value with which I could work on the object.

Best,
Juergen

Ok, with the DataGridView bound to the BindingSource, disregard what I was saying before.  The DataGridView will handle adding and deleting from the underlying class list.  All you need to do is to write some code that will take the list and update the persistent storage.

Bob

Have the same problem as you did.. It seems it is the TableAdapter that we must use (http://msdn2.microsoft.com/en-us/library/bz9tthwx(VS.80).aspx). I do not see any problems if you use it together with INotifyPropertyChanged (http://msdn2.microsoft.com/en-us/library/system.componentmodel.inotifypropertychanged(vs.80).aspx) for updates....

Not sure of how to delete objects and crating new ones yet (have foreign keys and stuff in the db). Any suggestions?

Ah...found the solution (http://msdn2.microsoft.com/en-us/library/ms233815(VS.80).aspx) will try it out tomorrow.. at first glans It felt like it was a lot of work....

Hi dogbrain,
your link in the last comment mentions I can use the DBDirect methods:
"You save data back to the database by passing the values from your object to the TableAdapter's DBDirect methods.
Visual Studio creates DBDirect methods that can be executed directly against the database.."

But they refer to the Tableadapter. So I guess they mean the Web environment.

If you find a solution for winapps: make a minimalist approach and publish the source here as a comment.

My feeling is is that it is not possible.
Or better to say: It is possible only with a large amount of work. But I will not invent or write a whole new database system for a object db under winapps.

It has to be an easy or at maximum a moderate solution. And a general soulution. Not for a specific case.

I am just trying to learn how to use the objectdatasource and have given it up last saturday as it took too many personal resources.
Never the less I am still VERY interested when someone can show me a solution.

Best
Juergen

Eh did you look at the tutorial? DataSets are used by all kinds of applications (not just web) and in the dataset there are a tableadapter. The link I gave is to a windows application with step by step instructions. (I am working through it myselfe as soon as I have downloaded Northwind)

To be more clear: You wont use the DataSet.. only the TableAdapter it creates...

Ok.. now I have had some time to implement it. The key to everything besides using the TableAdapter is to use BindingList<T> as your data source....

The functions that you need to override are these:

protected override object AddNewCore()  called when a object is created. then calls insert
public override void CancelNew(int itemIndex)
protected override void InsertItem(int index, Customer item)
public override void EndNew(int itemIndex) called when something has changed (basicly after everything)
protected override void RemoveItem(int index)
protected override void SetItem(int index, Customer item) (Not sure if we need to change anything here)

So create a class that inherits BindingList<T> that holds your buissnessobjects..

Use it as a datasource... (just att it like a normal objectDataSource and then replace it in the forms load event)

Add debug breakpoints on all the above functions and see what happens when you use it in a DataGridView and a details view.

More info about BindingList<T>: http://msdn2.microsoft.com/en-us/library/ms132679(vs.80).aspx

Hi dogbrain!
On my first vomment here:
"On load of the grid form form I assign to the gridView.Datasource my List<myClass> function value."

I used also BindingList. Mentioned: 11.10.2007 at 02:48PM CET, ID: 20255541

That didnt work.

I didnt get so far a TableAdapter for the objectdatasource.
When you write I shoud overwrite methods: On which object?
The non existing tableadapter or the datagridview?

If I have a working tableadapter on the objectdatasource I have no problem. But so far I haven't one.

Best
Juergen

Hi dogbrain!

First of all: Many THANKS for your efforts.

This time it really looks good!

Deleteing is easy. RemoveItem is called one time, so it is safe just to pick up a key value from item to delete the item on a DataBase!

Creating has a good point in InsertItem. Just annoying is that on start it is called every time when the grid loads itself with values.
Any idea how to avoid this in the beginning? How to differ a loading datagrid from a real Create?

Creating calls EndNew 2 times before entering data, 3 times when leaving the new row.
EndNew is even called when no changes are made a gridline, just changing the line.

Using EndNew for an update would create a substancial overhead when writing the data out each time to a background database.

Do you have an idea how to catch changes made to row so only a dirty row would deliver data?
Or is there an easy check if the data have changed for that item?

Best
Juergen

Hi dogbrain!
I think I resolved the issue regarding the edit:
I created an object (not database related) field IsDirty.
Then each property set got an entry like:
  if(value != _User) _isDirty = true;

EndNew got an:
        if(this[itemIndex].IsDirty) {
        ... update database/clearing IsDirty
        }

This should work with edititing.

============================================

Deleting is resolved.

============================================

Inserting and the annoying call on load in InsertItem is resolved by:
class level:
    private bool loading = false;
Then    
    in InsertItem:
    if(!loading) create new DB record

    In the constructor which loads the list/gridview:
      loading = true;
      LoadUsers();
      loading = false;

============================================

I just need to check by some examples if all cases are covered.

If you come up with better ideas: Great!
I am willing to learn everything what is better.

So far: I am going to check the solution by examples
when I have some more time.

And again a big thank you for your help.
I appreciate that you take the time and patience to help me.

I will hopefully find a chance to return this some time to the community.

All the best
Juergen

No problems, great that it worked for you.... :)

I am trying to get it to work over remoting at the moment.... not looking good...

By the way you can use the events on bindinglist instead...... Easyer to use.. You need to implement INotifyPropertyChanged in the object datasource to get the updates (if I remeber it correctly:
(http://msdn2.microsoft.com/en-us/library/ms229614(vs.80).aspx)

Do something like this:
BindingList<RentalLibrary.Administration.AUser> a = Administration.User.getActiveUsers();
a.AddingNew += new AddingNewEventHandler(a_AddingNew);
a.ListChanged += new ListChangedEventHandler(a_ListChanged);

And the functions:
void a_ListChanged(object sender, ListChangedEventArgs e)
{
      if(e.ListChangedType== ListChangedType.ItemAdded)
            //etc
}

void a_AddingNew(object sender, AddingNewEventArgs e)
{
      e.NewObject = new Administration.User(true);
}

Hi dogbrain,

I played a bit with these events but they have a significant disadvantage in my eyes:
i.e. deleted event is called when the object is gone. So you have no "key" property to grab which you need for deletion in a database.
The RemoveItem looks to fit better as the object exists and you have an index to the object.
In my eyes the event is for cleanup a good idea not for the deletion itself.

The same with InsertItem: that is called AFTER the event. So the object event e.NewObject is null and I do not know what happens whe you create the object here (and how?). The event maybe good for some preparation b4 the actual creation of the object in InsertItem.

BTW: In ListChangedEventHandler  if(e.ListChangedType == ListChangedType.ItemChanged) is never fired!
This maybe a point of consideration for updates. But to take a closer look to the context I need to debug there.

Thanks for your hint(link on "INotifyPropertyChanged Interface".
I will take a closer look to it if that is better than my isDirty property.

I just implemented INotifyPropertyChanged and wow: the ListChangedType.ItemChanged worked!

Best
Juergen

So.. will you accept an answer?