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Well as some of you know I was using a tab control for a project I was

building for my boss.



Today he tells me that he wants:



When he switches tabs to be able to switch back and see whatever it was he

was doing on the other tab.



That may not sound like a big thing but I used the same controls for each

tab and then manually cleared the page so he didnt see the same in another

page. (datasource cleared out etc)



This is what I did:



If TabControl1.SelectedIndex = 2 Then

DataGrid1.DataSource = Nothing

DataGrid2.DataSource = Nothing

Label2.Text = ""

Label18.Text = ""

'actions to fill them wiht new values

End If

If TabControl1.SelectedIndex = 1 Then

DataGrid1.DataSource = Nothing

DataGrid2.DataSource = Nothing

Label2.Text = ""

Label18.Text = ""

'actions to fill them with new values

End If



I have to clear it on their arrival other wise they will see the data from

the other page, right?



Is there any way I can retain what they did without being forced to create

different controls on each tab page?


-

Scorpion,



What is the big deal with having two more grids or you could cache the

datasource



Dan





"scorpion53061" <scorpion_53061nospamhereplease@yahoo.com>wrote in message



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if i recall corectly he's talking about a lot of tabpages

i do have a suggestion let us know how it turns out

create a class that holds all the data of 1 tabpage and an integer to tell w

tabpage we are talking about (even better put them in an array, creating

class arrays has been talked about a while back)

it could have some datasets, strings, ...

put the code to manipulate the data in the class

when the user selects a tabpage populate it from the class, if it's a new

one it would be blank or you get it from the db, if it's already filled in

populate it from the class.



hope it helps



eric



"solex" <solex@nowhere.com>wrote in message



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Hi Eric,



I was thinking about that solution you told also, but than I did look to the

answer/question from Solex and thought, yes Solex is right, why would

Scorpion just use one datagrid, while more will maybe fix his problem very

simple.



What are your arguments not doing that, I really was in doubt if I would

give the same answer as you?



Cor





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if i'm not mistaking he has 28 tabpages that use this (again if im not

mistaking there could be more in the future)

i thought he wanted something that would work for 3, 10, 28,100, ...

tabpages and do'nt give to much work for an additional page.



imagine if you have to change something in your code, do you want to do it

once or a 100 times?



an alternative would be creating a control array, but since he seems to have

something working now it seemed bether to expand on that.



eric



"Cor" <non@non.com>wrote in message



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Hi EricJ,



I understand now, but thinking on it I think I would do it by making a user

control and put that in an array then ( I never did, but I would try it

first if it was my problem)



:-)



Thanks,



Cor





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Hi eric you are correct. This had 28 tab pages.



The only way I could see this working was to make duplicate controls for all

the tab pages.



Now on your suggestion you I am sorry to ask this but would you take a

control such as a datagrid (I also have to do this with several other types

of controls) and show me how you would do this? Just enough to help get me

started on what you are describing.





"EricJ" <ericRéMoVe@ThiSomnipack.be>wrote in message



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I have something that worked here........it is so simple I may not be

thinking of someting but here goes.....



I declared at the module level 28 different dataviews - one for each tab

page datagrid.



When the user selects that tab page it binds to that view.



The data is there when it is supposed to be and not there when it is not

supposed ot be. It also retained the formatting I call for in code. The only

downside is when there were zero rows it showed a datagrid with one square

in teh left hand corner for the grid but I think I can get away with that.



My concern is obviously what effect 28 dataviews will have on the users

resources, and down the road when I need to update the views when the user

is not looking at the tab page if it will be difficult to do.



I assume adding or removing a row from a view is not that hard. At least I

hope.



What do you guys think?





"EricJ" <ericRéMoVe@ThiSomnipack.be>wrote in message



-

this is roughly w i had in mind (ok you will still have a lot of dataviews

but i doubt that will be a problem, its a lot better then accessing the db

all the time).

use the property's of the class in your application

\\

'first a class

Public Class test

Private dv As DataView

Private str1, str2 As String

Public Sub New()

dv = New DataView

str1 = ""

str2 = ""

End Sub

Public Sub New(ByVal dview As DataView, ByVal string1 As String, ByVal

string2 As String)

dv = dview

str1 = string1

str2 = string2

End Sub

Public Property dView() As DataView

Get

Return dv

End Get

Set(ByVal Value As DataView)

dv = Value

End Set

End Property

Public Property String1() As String

Get

Return str1

End Get

Set(ByVal Value As String)

str1 = Value

End Set

End Property

'...

Public Sub load()

'load the data from your db here

End Sub

Public Sub save()

'save the data in the db here

End Sub

'...

End Class

//



in your app create an array of the class



\\

private arrtest(28) as test

//



when you use it for the first time



\\

arrtest(i) = new test

'i would be the index of the tab page

//



then fill the controls w the class



"scorpion53061" <scorpion_53061nospamhereplease@yahoo.com>wrote in message



-

scor,



Obviously I am coming into this a little late, but if you expect this

particular part of the project to continue to grow (i.e. increasing the

number of tabs as time goes on) might I suggest you change your UI design.



I am not familar with the domain problem you are trying to solve but I

cannot imagine that a window with 28+ tabs is going to be particuarly easy

to use. Perhaps a menuing system or treeview will help with navigating to

the particular pages and only load what is necessary upon the users request



To answer your question I think that the approach of having multiple

datagrids and refreshing the datasource when the user clicks on the

approprate tab (and clearing the datasource when the tab has lost focus) is

probably your best bet if you cannot change your GUI.



This way you know that the amount of memory used will grow at resonable

rate. Esentially then number of datagrids times the amount of memory used

per datagrids + the size of the current dataview. If you cache the

dataviews then your memory usage will eventually (if not already) surpass

the above senario as the dataviews increase in size.



Good Luck!

Dan





"scorpion53061" <scorpion_53061nospamhereplease@yahoo.com>wrote in message



-

The way this was working was that whenever a tab was clicked it was told to

add the same set of controls to the page. (2 datagrids, 8 labels, six

buttons)



Do you think that as each tab page is clicked that the framework will

iniitiate garbage collection as needed or do I need to manually somehow

dispose of the controls to keep them from bombing the resources on the

computer?



As far as why the tab control was chosen that was the bosses choice. IT

certainly was not mine. I have not cared for the trouble this particular

control has caused me. Granted, my inexperience with the control has been a

factor, but there are some bugs with this control that make life

interesting.



I don't want to clear the datasource when teh leave the tab page otherwise

the user when they return will not see what they had done when they were

there previously. My concern is how to keep the various dataviews updated if

things they do on other tab pages affect what result they should be viewing.

Using the same datagrid presented binding problems but what I did was create

a dataview for each screen's grid and told to bind to that dataview when

they returned.



Thanks much for your thoughts. If you have more I would love to hear them.



"solex" <solex@nowhere.com>wrote in message



-

Let me reiterate to make sure I understand your requirements



(1) the dataviews you have are based on a datatable.

(2) there are 28+ dataviews that you need to maintain their state as they

are changed by the user

(3) if a dataview is changed in a way the updates the underlying datatable

you do NOT want the other dataviews to be updated.

(4) persumably you want the user to have the ability to view all of thier

changes before they commit the entire set of changes to the underlying

datatable.



Is this correct?



Dan





"scorpion53061" <scorpion_53061nospamhereplease@yahoo.com>wrote in message



-

Hi Scorpion,



I am curious also and I take the text from Solex



1) the dataviews you have are based on a datatable.



Is every dataview also one datatable or are all dataviews, views on the same

datatable (as part of a dataset or more datasets)?



Cor







-

Each has their own dataset and can be updated (row delete, modify, add)

independantly.



What I want to do is in some cases but not all changes in one dataview may

need to be reflected in another dataview.





"Cor" <non@non.com>wrote in message



-

1 the dataviews are based on several tables. Each dataset has its own

dataview the way it is currently set up. Each dataset is copied to another

dataset called dscopy so that formatting rules and such can be applied

without having to write 28 formatting procedures.



2-3. Yes I need to maintaint their state but I also need to be able to

adjust it. For example if an item is added ot the order the order dataview

would need to be addressed so that when they returned to that screen the

item would show as being there.



4. Would be a very nice addition. DO not currently have it in place however.

Open to anyting here.



I hope I am clear. It is confusing I know.



"solex" <solex@nowhere.com>wrote in message



-

scor.,



Based on your comments, I am not really sure what would be the problem in

updating the underlying datasets as changes to the data is made. For

instance consider the following sequences



User makes changes to Page N

System updates underlying dataset as a result of the changes

System updates underlying dataset(s) for any dependent tables

System refreshes current Page



User selects new Page

System recreates underlying dataset for New Page

System recreate undelying dataview and rebinds



Obviously your application is getting compilcated and based on my

experience and from what I can gather from your descriptions, I would start

thinking about creating an object model that houses both the data and the

interactions between the objects and ditch the DataTable/DataView

assemblies.



IMHO the DataTable and DataViews /Binding will only get you so far and then

you hit a brick wall. I'm sure that there are work arounds and neat tricks

to get things to work but at what point do you say to yourself that the code

you have created is too complicated and too difficult to modify if you need

to add a new feature such as item (4) in my previous post.



Dan





"scorpion53061" <scorpion_53061nospamhereplease@yahoo.com>wrote in message



-

Hi Scorpion,



I was busy with something to investigate for Elena when I got this idea.



It is very quick and very dirty, but maybe it gives you some ideas



Cor

\\\\

Private dts(28) As DataTable

Private tabpages(28) As TabPage

Private dvs(28) As DataView

Private Sub DataForm1_Load(ByVal sender _

As Object, ByVal e As System.EventArgs) Handles MyBase.Load

Dim Tabcontrol1 As New System.Windows.Forms.TabControl

Tabcontrol1.SuspendLayout()

Tabcontrol1.Dock = System.Windows.Forms.DockStyle.Fill

Tabcontrol1.Location = New System.Drawing.Point(0, 0)

Tabcontrol1.Name = "TabControl1"

Tabcontrol1.SelectedIndex = 0

Tabcontrol1.Size = New System.Drawing.Size(392, 216)

Tabcontrol1.TabIndex = 0

Me.Controls.Add(Tabcontrol1)

For i As Integer = 0 To 27

makedatatable(i)

tabpages(i) = settabpage(i, dts(i))

Tabcontrol1.Controls.Add(tabpages(i))

Next

End Sub

Private Sub makedatatable(ByVal number As Integer)

dts(number) = New DataTable("Action")

dts(number).Columns.Add(New DataColumn("Item", _

Type.GetType("System.Int32")))

dts(number).Columns.Add(New DataColumn("Alfa", _

Type.GetType("System.String")))

For i As Integer = 0 To 10

Dim dr As DataRow = dts(number).NewRow

dr("Item") = i * number

dr("Alfa") = (i * number).ToString

dts(number).Rows.Add(dr)

Next

dvs(number) = New DataView(dts(number))

End Sub



Public Function settabpage(ByVal number As Integer, _

ByVal datatable As DataTable) As TabPage

Dim TabPage2 As New System.Windows.Forms.TabPage

TabPage2.Text = number.ToString

TabPage2.Dock = DockStyle.Fill

Dim datagrid2 As New System.Windows.Forms.DataGrid

datagrid2.HeaderForeColor = System.Drawing.SystemColors.ControlText

datagrid2.DataSource = dvs(number)

datagrid2.AllowSorting = True

datagrid2.ReadOnly = False

datagrid2.Dock = DockStyle.Fill

Dim dgts As DataGridTableStyle = New DataGridTableStyle

dgts.MappingName = "Action"

dgts.GridColumnStyles.Add(New DataGridTextBoxColumn)

dgts.GridColumnStyles.Item(0).MappingName() = "item"

dgts.GridColumnStyles.Item(0).HeaderText = "Action"

datagrid2.TableStyles.Clear()

datagrid2.TableStyles.Add(dgts)

datagrid2.Refresh()

datagrid2.Visible = True

datagrid2.ColumnHeadersVisible = True

TabPage2.Controls.Add(datagrid2)

Return TabPage2

End Function

////





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