Re-Order an ArrayList in C#

An interesting problem I keep coming across is how to re-order an arraylist item up or down, it's something I've needed to use on a number of applications, so I figured it's about time I got my head round the problem, and it's surprisingly simple.

First we create an Arraylist and populate it:        

    ArrayList MyRA = new ArrayList();               
    MyRA.Add("Item1");        
    MyRA.Add("Item2");        
    MyRA.Add("Item3");        
    MyRA.Add("Item4");        
    MyRA.Add("Item5");

Next we identify the item we want to move:        

    String myItem = "Item4";

And create an integer to hold the position of the item:        

    Int32 myIndex = new Int32();

Now get the position:        

    myIndex = MyRA.IndexOf(myItem);

Almost there, now we insert the Item at that the position before it's current on (Position - 1):        

    MyRA.Insert((myIndex - 1), myItem);

Finally we need to remove the old item, it's position would have moved up one since we've added an extra item:                

    MyRA.RemoveAt((myIndex + 1)); 

So if you're in a hurry and just want the full code here you go:        

        ArrayList MyRA = new ArrayList();
        String myItem = "Item4";
        Int32 myIndex = new Int32();

        MyRA.Add("Item1");
        MyRA.Add("Item2");
        MyRA.Add("Item3");
        MyRA.Add("Item4");
        MyRA.Add("Item5");

        myIndex = MyRA.IndexOf(myItem);
        MyRA.Insert((myIndex - 1), myItem);
        MyRA.RemoveAt((myIndex + 1));

Of course this only moves items down the list, to move them up simply reverse the numbers on the last two lines:        

    MyRA.Insert((myIndex + 1), myItem);        
    MyRA.RemoveAt((myIndex - 1));

Happy Coding :0)

Tags: ArrayList, Re-order, c#

Validate DropDownList - Bilal Haidar [MVP]

I just came across this article on how to use a required field validator on a dropdownlist control - I think the beauty of it is it's simplicity:

By setting the Required Field's InitialValue property to be the same as the Dropdownlist's default value, we can force the validator to "kick off" if the value isn't changed.

Thanks to Bilal Haidar for the solution:

<asp:DropDownList id="DropDownList1" runat="server">
    <asp:ListItem Value="-1">--> Choose <--</asp:ListItem>
    <asp:ListItem Value="1">Lebanon</asp:ListItem>
    <asp:ListItem Value="2">Kuwait</asp:ListItem>
</asp:DropDownList>

<asp:RequiredFieldValidator id="RequiredFieldValidator1" runat="server" ErrorMessage="You must select a valid option" ControlToValidate="DropDownList1" InitialValue="-1" Display="Dynamic" />
<P>
    <asp:Button id="Button1" runat="server" Text="Post Back" />
</P>

Validate DropDownList - Bilal Haidar [MVP]

Tags: Dropdownlist, RegularFieldValidator, validation, ASP.NET 2.0, MVP

Formview default mode

If your using a formview on a page it might be useful to set the default mode dynamically depending on whether the datasource returns a record or not.

For example I'm using a formview to populate a table - if a record already exists for my criteria I want to edit it, otherwise I want to add a new one.

I could test the datasource directly but I thought it would be neater to actually test the formview itself after it's databound. i.e.

protected void FormView1_DataBinding(object sender, EventArgs e)
    {
        if (FormView1.DataItemCount < 1)
        {
            FormView1.DefaultMode = FormViewMode.Insert;
        }
        else
        {
            FormView1.DefaultMode = FormViewMode.Edit;
        }
    }

Works a treat - I guess there could be lots of ways to achieve this, if anybody has any let me know. But it works for me :0)

Ta Dean

Blogged with Flock

Tags: c#, formview, databinding, datasource, defaultmode

SQL2005 Failed to Load

Blogged with Flock

Tags: SQL2005, Domain Permissions, Failed to Load

Populating a list box dynamically

I've just had to fix a colleagues code, which had the same problem that I'd been struggling with yesterday - it's another one of those annoying quirks that has you tearing your hair out because you look at your code and even though it compiles it still wont work.

The issue was that we are trying to populate a dropdown list dynamically - using the c# funtion

dropdownlist.items.add("Text","value");

Although this does compile it didn't seem to work - I stand to be corrected. The way I got round it was to create a new listitem object and populate it with my text and value. i.e

dropdownlist.items.add(new ListItem("Text","value"));

Hope this helps somebody cus it's such an annoying thing to get stuck with - another point was that the value must always be a string - you can cast it when you retrieve it - (Convert.ToInt32(dropdownlist.selectedItem.value) but it seems to only want strings (I guess this is because the value is going to be rendered into HTML so any cast information will be obliterated anyway. A Little like the classic ASP Response.Write("Some HTML") used to work.

Blogged with Flock

DataFormatting String {0:d}

I've had this problem a few times so I thought I'd actually get round to blogging it.

Displaying Dates on a Datagrid is a nightmare when you don't want to display the full date and time in dd/mm/yyyy hh:mm:ss format.

There is a useful little property in the datagrid items editor which allows you to specify the format of the string using {0:d} formatting.

The problem I've found was that no matter what I did, it didn't make a bit of difference to the output.  The solution after much googling was was set one of the other properties..

The trick is to set HTMLEncode to False - as if by magic it works.

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Assumed consent is evil and maybe illegal

Assumed consent is evil and maybe illegal