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Hi there,
Help! Is there any consensus as to the best way to handle dynamic button clicks? The buttons are being created dynamically and conditionally placed, depending on business logic.
Our problem is that on clicking such a button, the postback calls the Page_Load but not the Button_OnClick. I notice that if I use a static button on the page, this problem does not occur, but that thwarts our business logic.
What we're trying to achieve is to add an "Edit" button. When clicked, it changes the layout of the page (i.e. the aspx page), and no longer shows this "Edit" button. Instead, "Save", "Discard", etc...).
We're trying to avoid making the buttons static, with visibility controlled by logic, as that would be such a limiting factor. e.g. we may want a dynamic array of buttons where the size of the array is unknown at design time. How would their click events be caught?
Any ideas?!
Stewart
Button EditButton;
protected void Page_Load(object sender, EventArgs e) {
if (!IsPostBack) {
setupMostOfPage();
}
if (!editMode) {
setupEditButton();
}
}
EditButton_OnClick(object sender, EventArgs e) {
editMode = !editMode;
setupMostOfPage();
}
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Are you hooking the Click event of the buttons in the setupEditButton method? Keep in mind that all controls are 'dynamic', even the ones created at design-time. Just inspect the code generated by VS when you create a button in the designer, and make sure you cover all your bases by comparing your code to the generated code.
:josh:
My WPF Blog[^]
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If a static button can be 'remembered' between posts, can something be done to a dynamic one to persist it too?
John
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The basic problem you have here is page life cycle. Between page init and page load, a control tree is built. After page load, this tree is populated with events from viewstate, which are then called. If your button does not exist prior to page load, it will not be in the tree, and so the event is lost.
Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog
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Does this mean that dynamic buttons can never be used in webforms as the postback can't find the handler? If so, what's the point in their existence?
John
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No, it means you have to be careful where you create them. I agree this can be a major problem, but it's doable, I've certainly done it. The LoadViewState method is the best place to create your buttons, as it's the last possible moment. Overload it, create your controls, then call the base method to load the view state.
Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog
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Clever! This looks like the way, but I'm still having a few problems.
I find that the eventable control also has to be placed on the page, else its handler doesn't get called. Awkward if the handler changes the logic so that it shouldn't be placed! I got round that by using an invisible static PlaceHolder.
However, even with that, I can't always get the handler being called. Is there a best way of tracking the events in the debugger? I've not yet persuaded VS to do this.
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The control needs both to be present and to be in the same place in the control tree for it to get it's event. You can set it's visible property later, if you want to hide it.
Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog
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Hi,
Using VS2003 and C#, I have created oleDbAdapaters to fill a data set and used a combo box to allow easy selection of choices for amending record fields. Here's the code for the combobox:
// comboBoxMembershipLevel
//
this.comboBoxMembershipLevel.DataBindings.Add(new System.Windows.Forms.Binding("SelectedItem", this.myClubDataSet12,"MembershipLevels.MembershipLevelName"));
this.comboBoxMembershipLevel.DataBindings.Add(new System.Windows.Forms.Binding("SelectedValue", this.myClubDataSet12, "MemberDetails.MembershipLevel"));
this.comboBoxMembershipLevel.DataSource = this.myClubDataSet12.MembershipLevels;
this.comboBoxMembershipLevel.DisplayMember = "MembershipLevelName";
this.comboBoxMembershipLevel.Font = new System.Drawing.Font("Microsoft Sans Serif", 8.25F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, ((System.Byte)(0)));
this.comboBoxMembershipLevel.Location = new System.Drawing.Point(584, 80);
this.comboBoxMembershipLevel.Name = "comboBoxMembershipLevel";
this.comboBoxMembershipLevel.Size = new System.Drawing.Size(121, 21);
this.comboBoxMembershipLevel.TabIndex = 40;
this.comboBoxMembershipLevel.ValueMember = "MembershipLevel";
//
The table "MembershipLevels" has three fields - ID(autogenerated key), MembershipLevel(int) and MembershipLevelName(text). The MemebershipLevel is stored for each record in the table MembersDetails.MembershipLevel(int).
When I select the first member of the drop down list and then move away and back to the record concerned I get 'System.Data.DataRowView' in the display box. Chosing any of the other members of the drop down list and all works fine - it only occurs when I chose the first member of the drop down list.
Saving the changes from the dataset to the database whilst the 'System.Data.DataRowView' is showing updates the database with the correct field data (ie a number and not 'System.Data.DataRowView').
I can't find any help after much searching the net.
Anyone know why?
TIA.
Regards,
Glen Harvy
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Why are you adding items to the combo's Databindings collection and setting the DataSource. That's not a normal thing to do, it might be "confusing" the combo's databinding logic. Does the problem keep happening if you remove these two lines?
this.comboBoxMembershipLevel.DataBindings.Add(new System.Windows.Forms.Binding("SelectedItem", this.myClubDataSet12,"MembershipLevels.MembershipLevelName"));
this.comboBoxMembershipLevel.DataBindings.Add(new System.Windows.Forms.Binding("SelectedValue", this.myClubDataSet12, "MemberDetails.MembershipLevel"));
:josh:
My WPF Blog[^]
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Thanks for your assistance:
Josh Smith wrote: Why are you adding items to the combo's Databindings collection and setting the DataSource. That's not a normal thing to do,
The form is a collection of all the data related to one record with the ability to move forward and backward between records. I want to be able to change the dataset values of these individual records/fields via a combobox selection of options as they are displayed. Adding the items to those form fields allows this to happen except with the problem as descibed. The change in values is also detected correctly and saved to the database.
Josh Smith wrote: Does the problem keep happening if you remove these two lines?
This resolves the problem as described BUT if I change the data in the field then the new data displayed in the field remains constant no matter which record I move to. In other words, the dataset is not updated. Additionally, the change in the fields value is not detected and the database is not updated when requested.
HAVING SAID ALL THE ABOVE
I changed the source as you suggested and do you think I can now return the code back to what it was and get it to work as described above 
It strikes me that I'm trying to do something in a way that can't be done.
Any suggestions 
Glen Harvy
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I am using listview to display an entity called step. I am displaying the Name of the steps in the list and keep the STEP object in each item's TAG.
The listview properties I am setting are,
alignment = Top
View = SmallIcon
After getting the data in the listview, I am using following two lines
lstSteps.Sorting = SortOrder.Ascending;
lstSteps.Sort();
Because of sorting : some items appear in the line of other items rather than all items one below other.
I am sure this is happening only after i apply sorting. Without sorting it is working fine.
Due to some restrictions I cannot apply sort before getting that entity (steps) in ListView
Plz help me
abhijeet
-- modified at 9:20 Wednesday 12th July, 2006
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The SmallIcon view is implicitly multi-column, so if you don't want the items to wrap, set the View to List. The List view only has multiple columns if you explicitly add sub-items.
:josh:
My WPF Blog[^]
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Hi,
View = List is multicolumn too. See this answer[^]. I think it will help you too.
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Hi, i have a situation where i need to make a copy of an existing excel 2003 workbook by "excluding one worksheet", using c#.
Note: I am using .Net 1.1 framework
Plz help me out with this, its very urgent.... Thx in advance.
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Try recording macro in Excel when deleting sheet, and then rewrite this macro code in C#.
My english is bad. Please, correct my errors.
Best regards, Alexey.
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hi, how can i read an xml file and put its elements values on textboxes
Thanks alot
Hamody
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Use XmlDocument and see MSDN about XmlDocument.
for example :
XmlDocument xmlDoc = new XmlDocument();
xmlDoc.Load(@"c:\myfile.xml");
xmlDoc.ChildNodes...... etc.
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thanks a lot for your rapid help,
may u please send me the URL for this sample cause am working now on the project and it has to be done as soon as possible
Thanks alot
Hamody
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See this sample from this forum:
http://www.codeproject.com/script/comments/forums.asp?forumid=1649&mode=all&userid=1957547&select=1569224&df=100&mpp=50&fr=263#xx1569224xx
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My need is when a client request for listening music,instead of streaming ,i want to save that requested file in the client machine & play it using <embed /> tag,the saving of file is done in backside the client will n't know about it,But when i download that file it ll pop up the window for saving or open or cancel,which i don't need,my procedure seems like streaming of the file.
Bibhu Shankar Panigrahi,
Software Developer
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In one of my VB6 Application, I have used MSXML2.ServerXMLHTTP50 Object to send XML message to other application(Tally7.2 Accounting Software) and receive response in XML from it. I communicate it by giving Computer IP address and Port Number of Tally.The Code is
Dim serverHTTP As New MSXML2.ServerXMLHTTP50
ReqListOfCmp = _
"<ENVELOPE>" & _
" <HEADER>" & _
" <TALLYREQUEST>Export Data</TALLYREQUEST>" & _
" </HEADER>" & _
" <BODY>" & _
" <EXPORTDATA>" & _
" <REQUESTDESC>" & _
" <REPORTNAME>List of Companies</REPORTNAME>" & _
" <STATICVARIABLES>" & _
" <SVEXPORTFORMAT>$$SysName:XML</SVEXPORTFORMAT>" & _
" </STATICVARIABLES>" & _
" </REQUESTDESC>" & _
" </EXPORTDATA>" & _
" </BODY>" & _
"</ENVELOPE>"
PortNo = txtPortNo.Text
serverHTTP.Open "POST", "http://localhost:" & PortNo, False
serverHTTP.send ReqListOfCmp
respListOfCmp = serverHTTP.responseText
Problem is That now I want to do the same thing in C#. What class i have to use in place of MSXML2.ServerXMLHTTP50. As I have to communicate using XML over Http with a Non DotNet Application(i.e Tally). I have tried to search with Remoting but as Server is one of the Non-Dotnet application I am not able to do it.
Plz help me , its urgent..................Thanks in Advance
Abhinav
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I have a DataGrid in a web page which displays results. Now I
want to show some string contents instead of numeric values of a field.
For example I have a field "Type" with (0/1) values and I want to show
(Individual/Company) instead of (0/1) numbers.
I'm using C# .NET
Thanks.
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I'm new to C# and now i need help in saving a .doc file with pre-filled information and use bookmarks to update certain aspects of data in that file like address and name, taken from a database.
none
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Is there an easy way in C# to quary all tables from a database and write them to a XML-file (basically turning a database into XML)?
Johan
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