Re: How to convert object to user define type by a typename string? - C# Discussion Boards

leppie23-Sep-02 5:51

leppie

23-Sep-02 5:51

Hi
I assume you are inheriting from ArrayList. You should inherite from CollectionBase and expose the protected List 's methods as it needs like:

public virtual void Add(Item value)
{
this.List.Add(value);
}

I did this in a few minutes and everything works 100%. IMPORTANT: Like all designer related stuff, the custom (really a strongly typed) collection as well as the objects inserted into the collection MUST have default constructors.

Cheers Smile | :)

Give them a chance! Do it for the kittens, dear God, the kittens!

Maciej Pirog25-Sep-02 7:53

Maciej Pirog

25-Sep-02 7:53

Strange! Take a look at my code:

public class R
{
        public R(){a=10;b=56;}
	int a, b;
	public int A{
		get{return a;}
		set{a = value;}}
	public int B
	{
		get{return b;}
		set{b = value;}
	}
}

public class Col: CollectionBase 
{
	public Col(){}
	public virtual void Add(R valueT)
	{
		this.List.Add(valueT);
	}
// ...
}

But the designer still adds the System.Object item, not the R item. What's wrong?

Ñ There is only one MP Ð

leppie25-Sep-02 9:18

leppie

25-Sep-02 9:18

Hi MP

Actually I realised today that you just need the indexer Smile | :)

CollectionEditor from MSDN:

Notes to Inheritors: This editor can edit collections that have an Item property. The editor can determine the type of the collection from the Item property, if it exists. If the collection does not have this property, or if you want to provide collections of more than one type, you can override certain protected members of this class to customize the editor to support other types of collections.

so just do this:

public MyItem this[int i] 
{
  get {return (MyItem) base.List[i];}
  set {base.List[i] = value;}
}

Cheers

Give them a chance! Do it for the kittens, dear God, the kittens!

How to convert object to user define type by a typename string?

Maciej Pirog26-Sep-02 4:50

Maciej Pirog

26-Sep-02 4:50

Thanks!

Now it's working!

Ñ There is only one MP Ð

Winona22-Sep-02 20:26

Winona

22-Sep-02 20:26

I want to do something like this:

Type t1=Type.GetType("UserControl");
UserControl Control = (UserControl)Page.LoadControl("Components/UserControl.ascx");
control = (t1)Control;

while compiling,system say "could not find type or naming space t1".
How can I use my type to define a variable?
Thanks!

Re: How to convert object to user define type by a typename string?

Stephane Rodriguez.22-Sep-02 21:27

Stephane Rodriguez.

22-Sep-02 21:27

<br />
UserControl control = (UserControl)Page.LoadControl("Components/UserControl.ascx");<br><br />
Type t1 = control.GetType();<br><br />
// you can discover members and methods supported by t1 thanks to reflection :<br><br />
// .MemberInfo<br><br />
// .MethodInfo<br><br />
// ...<br><br />

More info : MSDN doc[^].

MS quote (http://www.microsoft.com/ddk) : As of September 30, 2002, the Microsoft® Windows® 2000 DDK, the Microsoft Windows 98 DDK, and the Microsoft Windows NT® 4.0 DDK will no longer be available for purchase or download on this site.

Re: How to convert object to user define type by a typename string?

James T. Johnson22-Sep-02 21:30

James T. Johnson

22-Sep-02 21:30

Winona wrote:
How can I use my type to define a variable?

You can't.

What you are trying to do is something called Late-binding which isn't supported natively by C#.

What you can do is use the methods in the Type class to use your class at run-time. In particular the InvokeMember can be used to get or set properties, run methods, etc.

There is an example in MSDN which will show you how to use it.

James
"And we are all men; apart from the females." - Colin Davies

Re: How to convert object to user define type by a typename string?

Winona23-Sep-02 20:15

Winona

23-Sep-02 20:15

Thanks all,I followed you advice and it worked.

Can you change the height of a Form's Title Bar?

Rodney S. Foley22-Sep-02 15:22

Rodney S. Foley

22-Sep-02 15:22

I would like to have the forms FormBorderStyle property set to any of the form border styles and then still be able to make the title bar thinner or taller.

Can someone help explain how to do this please.

Coding is a way of life.
It's in the air we breath.
It pumps through our vines.
Without it we soon crumble to dust.
- Rodney S. Foley

Re: Can you change the height of a Form's Title Bar?

Nnamdi Onyeyiri23-Sep-02 6:50

Nnamdi Onyeyiri

23-Sep-02 6:50

this is set by the operating system itself, i dont think you can change this.

Suspicious | :suss: Email: theeclypse@hotmail.com URL: http://www.onyeyiri.co.uk
"All programmers are playwrights and all computers are lousy actors."

Re: Can you change the height of a Form's Title Bar?

Rodney S. Foley23-Sep-02 11:56

Rodney S. Foley

23-Sep-02 11:56

(or change a FixedToolWindow to have round corners)

I would like to have the forms FormBorderStyle property set to any of the form border styles and then still be able to make the title bar thinner or taller. Would love a pure C# solution, but a InterOp would be acceptable.

Basically I would love to have a small narrow size like the FixedToolWindow title bar, but with ROUNDED CORNERS on the form not square. So actually either changing a normal size title bar to be thinner or changing a FixedToolWindow to have round corners. Which ever is easier.

I have been trying to figure this out for the last 3 days, so any help would be appreciated.

Re: Can you change the height of a Form's Title Bar?

leppie23-Sep-02 14:00

leppie

23-Sep-02 14:00

Hi

You can try doing a borderless window, and do the toolbar, round corners, etc yourself, but it really sounds like alot of work Smile | :)

Cheers

Give them a chance! Do it for the kittens, dear God, the kittens!

Maching the row in a datagrid to a row in a DataTable

stephen woolhead22-Sep-02 14:02

Re: Maching the row in a datagrid to a row in a DataTable

22-Sep-02 14:02

I have a dataTable set as the Datasource of of a dataGrid via a DataView.

The Table contains an ID field and a Description field, of which only the Description is displayed in the grid.

I want to be able to programatically retrive the ID from the DataTable based on a row in in the DataGrid.

How can I do this, even if the grid has been sorted?

Thanks

Stephen.

Paul Riley22-Sep-02 14:43

Re: Maching the row in a datagrid to a row in a DataTable

22-Sep-02 14:43

If the ID is still bound to a column which is marked as not visible then you should still be able to access it as if it was visible.

Paul

stephen woolhead22-Sep-02 14:48

Re: Maching the row in a datagrid to a row in a DataTable

22-Sep-02 14:48

Thanks for the quick reply, had over looked that simple idea!

Anyway, I would stil like to be able to get back to the row in the dataTable, is it possible?

Thanks

Stephen.

Paul Riley22-Sep-02 14:59

Re: Maching the row in a datagrid to a row in a DataTable

22-Sep-02 14:59

Not sure exactly what you mean. Can you expand on the question a little... give an example if possible.

Paul

stephen woolhead23-Sep-02 0:34

Re: Maching the row in a datagrid to a row in a DataTable

23-Sep-02 0:34

OK, say I had code that looked like this..

DataSet ds = GetMyDataSet () ;<br />
<br />
DataTable dt = ds.Tables["Results"] ;<br />
DataView dv = new DataView (dt) ;<br />
dv.AllowNew = false ;<br />
<br />
dataGrid1.DataSource = dv ;

And somewhere else I want to delete the current row in response to a button click from the tool bar.

I could do..

DataView dv = (DataView )dataGrid1.DataSource ;<br />
DataTable dt = dv.Table ;<br />
dt.Rows[dg.CurrentCell.RowNumber].Delete ;

But if the grid has been sorted by using the column headers this will no longer work as the grid row number no longer matches the row number in the dataTable.

What I would like to do is find a way to go from a row in the datagrid to the row in the datasource.

The delete is just an example, it is the row mapping that is realy of intreast to me.

Thanks

Stephen.

Paul Riley23-Sep-02 1:27

Re: Maching the row in a datagrid to a row in a DataTable

23-Sep-02 1:27

You could search through the DataTable for the record with the same ID column.

But I feel you're missing some of the power of DataSets. Try Adding a DataSet design to your project, define the layout of your dataset and set the ID as a <bold>Primary key.

This generates a DataSet-derived class with a lot more power, exposing methods like Search() or FindByXXX() [where XXX is the Primary Key name].

If you then want to duplicate your changes in some sort of database, take a good look at DataAdapters.

None of this is simple stuff when you first come to look at it but once you've done it a couple of times, you can start knocking them together in no time. Trust me, it's worth the initial effort.

Paul

stephen woolhead23-Sep-02 2:46

Re: Maching the row in a datagrid to a row in a DataTable

23-Sep-02 2:46

I kept the example short in an attempt to get the point of my question cross, is there a way to map the selected row in a datagrid to the related row in the underlying dataset.

I am unable to use DataAdapters as the original datasource is not supported by ADO.NET

I could use the Hidden ID column and search by Primary key method to find the row in the dataset, it just seems wrong when there must be a direct link back to the row in the dataset somewhere. The grid must know what row it is displaying to be able to update when the row is changed!

Also, on a related note, I want to do the same thing in DataGridColumnStyle derived class that uses columns in the DataTable that are not displayed in the grid. In this the edit and comit methods provide a row number in the datagrid, but I am at a loss on how to map that back into the dataset.

Stephen.

Paul Riley23-Sep-02 3:07

Re: Maching the row in a datagrid to a row in a DataTable

23-Sep-02 3:07

stephen woolhead wrote:
I could use the Hidden ID column and search by Primary key method to find the row in the dataset, it just seems wrong when there must be a direct link back to the row in the dataset somewhere.

There isn't, I'm afraid. DataSets and DataGrids are two completely unrelated things, Daatabinding just allows you to link them. You have to create your own link between records like that.

stephen woolhead wrote:
I am unable to use DataAdapters as the original datasource is not supported by ADO.NET

Not even using ODBC.NET[^]?

stephen woolhead wrote:
Also, on a related note, I want to do the same thing in DataGridColumnStyle derived class that uses columns in the DataTable that are not displayed in the grid. In this the edit and comit methods provide a row number in the datagrid, but I am at a loss on how to map that back into the dataset.

Through a primary key again, I suspect. You're stepping a little beyond my range of experience here though Smile | :)

Paul

stephen woolhead23-Sep-02 5:31

Re: Maching the row in a datagrid to a row in a DataTable

23-Sep-02 5:31

Paul Riley wrote:
Not even using ODBC.NET[^]?

I need to access a password protected Paradox table (not by choice Smile | :)

), and as far as I know there is no way to do that with ODBC. So I have a Managed C++ dll that uses the BDE directly to build me a Dataset.

Paul Riley wrote:
stephen woolhead wrote:
I could use the Hidden ID column and search by Primary key method to find the row in the dataset, it just seems wrong when there must be a direct link back to the row in the dataset somewhere.

There isn't, I'm afraid. DataSets and DataGrids are two completely unrelated things, Daatabinding just allows you to link them. You have to create your own link between records like that.

I have fianlly worked it out, looks something like this using the previous delete example...

BindingManagerBase cm = this.BindingContext[dg.DataSource] ;<br />
DataRowView drv = (DataRowView )cm.Current ;<br />
((DataRow )drv.Row).Delete () ;

I found this was a good link if you MSDN installed

ms-help://MS.MSDNQTR.2002APR.1033/vbcon/html/vbconConsumersOfDataOnWindowsForms.htm[^]

While there is no direct link between the dataSet and the DataGrid, there are container level objects that you can access that are looking after it for you.

Anyway, thanks for all your replies, they really helped.

Stephen.

Paul Riley23-Sep-02 5:42