Data Controls :: Check If Data Exist In List Generic Collection Using C#
Apr 19, 2014
i want to check my collection so i can add a new customer as long as the username does not exist in the collection i do not want 2 customers to be able to have the same username.
i have been trying many different things to try to get this to work but i am not exactly sure what i should be doing I have a aspforum and collection C# class of the list.
here is some things that i have tried
CustomerExists() i also have a collection of List<Customers>
//HERE IS MY EXISTS METHOD
public static Boolean IfCustomerExists(string login) {
List<Customer> theGuy = Collections.Customers;
bool exist = false;
foreach (Customer customer in theGuy)
[Code]....
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Mar 7, 2010
I was building an application for a project with .NET 3.5 and I noticed a weird behaviour of the List.Add method:
I have built my own class to organize data pulled from a database, and I use a while cycle to iterate through it.
However, when I List.Add(item), the whole content of the list is substituted with the last content pulled.
An example:
Suppose you have 3 users in a DB, each one identified with an ID and a username:
| ID | username |
| 1 | John |
| 2 | Fred |
| 3 | Paul |
and you have a "Users" class defined as
public class Users
{
private Int32 iD;
private String username;
public Int32 ID
{
get { return iD; }
set { iD = value; }
}
public String Username
{
get { return username; }
set { username = value; }
}
}
So you write this function:
[... SQL definitions - sdr is a SqlDataReader ...]
List<Users> userlist = new List<Users>();
if (sdr.HasRows) //There are users
{
Users user = new Users();
while (sdr.Read())
{
user.ID = sdr.GetInt32(0);
user.username = sdr.GetString(1);
userlist.Add(user);
}
}
What you expect (I expect) is userlist containing:
| ID | username |
| 1 | John |
| 2 | Fred |
| 3 | Paul |
What I actually get is, instead
| ID | username |
| 3 | Paul |
| 3 | Paul |
| 3 | Paul |
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Apr 19, 2010
I have developed an asp.net application ... I have a textbox where user will enter is name ... I need to check if the name is already exist in the database table column when ever user enter their name with out post back . If user exist mean it should show a msg user already exist .....
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GO
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GO
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GO
[code]....
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Oct 22, 2012
I need a list to export in excel and i need the following to achieve in the exported excell
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- Other Cell try should be 12px of the font
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Feb 15, 2010
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[Code]....
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Aug 19, 2010
I have a ListView which is filled by generic list of type MyClass. I can easily bind data from this list into ListView. But I have problems with reading data in opposite direction. This is my class:
[Code]....
I have also generic list of type MyClass:
[Code]....
Finally I bind data to ListView this way:
[Code]....
My ListView template:
[Code]....
How can I read data from ListView into my List list?
The operation of reading ListView data into List generic list should begin after clicking the button "GetData".
I saw the following advice:
[Code]....
but it does not work - the DataItem property of each Item of ListView has null value. The point is that I have generic list with data. I am binding this data into ListView which can be edited by user. After that after click Save or GetData data from ListView is read into generic list of MyClass type.
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Feb 5, 2010
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May 7, 2015
How to check username is exist in database or not without postback the page...
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Generic List to DataTable
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Aug 9, 2010
Split off from [URL]
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Jun 9, 2013
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<asp:TemplateField HeaderText="Interest">
<ItemTemplate>
<asp:DropDownList ID="ddl" OnSelectedIndexChanged="ddl_IndexChanged" SelectedValue='<%# bind("int_id") %>' AutoPostBack="true" runat="server">
</asp:DropDownList>
</ItemTemplate>
[CODE]
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Jun 9, 2010
I have a problem i just cant get around...I'm trying to sort the contents of a gridview that gets filled from a List<T>.
(working in DAL, BLL & Presentation layers).
The Gridview's source code:
[code]....
What i cant figure out is how to implement the sort method to the gridview when fetching data from a generic list... I have been Googling my a** of trying to solve this.
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I have a following generic list method that contains some data for a gridview. I need to supply edit and delete functionality for it.
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{
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Public Sub Send(message As String, id As String)
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[code]....
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Jan 24, 2011
We use gridview for showing a data from table.It show fine in certain case like in table field dispostion is data and test but in table we put the string Ineligible Member/Member No Longer Enrolled - Spoke to Target and Wrong Number After Skip Tracing then it gives error. 'DropDownList1' has a SelectedValue which is invalid because it does not exist in the list of items.
The following is snippest my code ,tell me where i am wrong.
[Code]....
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Oct 5, 2010
In my asp.net page I have a formview. In the formview's InsertItemTemplate I declare a dropdown list as below:
<td>
<asp:DropDownList ID="DropDownList6" runat="server" text='<%# Bind("District") %>'
DataSourceID="SqlDataSource6" DataTextField="District"
DataValueField="District">
</asp:DropDownList>
<asp:SqlDataSource ID="SqlDataSource6" runat="server"
ConnectionString="<%$ ConnectionStrings:ConnectionString %>"
SelectCommand="SELECT [District] FROM [tblDistricts]"></asp:SqlDataSource>
</td>
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<td>
<asp:DropDownList ID="DropDownList6" runat="server" selectedvalue='<%# Bind("District") %>'
DataSourceID="SqlDataSource6" DataTextField="District"
DataValueField="District">
</asp:DropDownList>
<asp:SqlDataSource ID="SqlDataSource6" runat="server"
ConnectionString="<%$ ConnectionStrings:ConnectionString %>"
SelectCommand="SELECT [District] FROM [tblDistricts]"></asp:SqlDataSource>
</td>
But whenever I try to edit the data I get the error:
'DropDownList6' has a SelectedValue which is invalid because it does not exist in the list of items. Parameter name: value And the values I am trying to edit were entered into the table by the dropdownlist declared in the insertitemtemplate dropdownlist6 listed above. And no values were deleted from the table.
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Dec 17, 2013
How to solver this error? I am getting error for "DropDown"
Error: 'DStation' has a SelectedValue which is invalid because it does not exist in the list of items.Parameter name: value on line: DStation.DataBind();
My .cs code is below
string CommandText = ("select distinct StationName from stations where DeletionDate is null");
DStation.DataSource = DataManager.DatabaseManager.GetOrCreateConnection
(DataManager.DatabaseManager.ConnectionType.MySQL).GetData(CommandText);
DStation.DataTextField = "StationName";
[Code] .....
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