DB Class - Populate DropdownList

[aconybeare]

Hi,

I'm trying to write a DB actions class for my web project to help reduce code duplication for example I want to show a dropdownlist with countries, populated from my DB, on more than one page, so instead of writing the code in each required page I thought that if I put it in a class I could then call a function i.e. populateCountriesDDL when required.

Does anyone know how to do this? Am I going about this the correct way or is there a better solution, with classic asp I would create an asp include file and add it in wherever needed

I've tried referencing

Imports System.Web.UI 
Imports System.Web.UI.HtmlControls 
Imports System.Web.UI.WebControls

but get error message - namespace could not be found for each of the above

Thought I could pass the function the DDL and populate it from there?

Any help will be greatly appreciated

Cheers Al

[d2005]

i havent a clue this is how i would go about it, IM NEW
perhaps some experinced members could read this and help further.
i havent done this yet but this is how im going to try it

create a class and do a get get countries function as dataset

public shared function getcountries() as dataset
dim dscountries as new dataset
dim sselect as string
' your select statement'
dim dacountries as new sqldataadapter(sSelect, connection())
dacountries.fill(dscountries, "country table")
'connection() is a private funtion in the same class that connects to database

then in your form code behind file - bind the ddl

this prob didnt help but might get the ball rolling for you

[mendhak]

A dropdownlist can be bound to an array. So what you need in your class is a function which will return an array containing all the countries with their values in the array. Make sense?

[aconybeare]

D2005,

Thanks, it's not quite what I had in mind, but as you say it's a start

Cheers Al

[GlenW]

Create a class with a static function that accepts a DropDownList as a parameter, then populates it.

To call it use;

MyClass.PopulateCountries(this.DropDownCountries);

[aconybeare]

Mendhak,

Thanks for that, I did think of doing it that way but would mean on each page I have to loop through the array populating my DDL as I want to be able to set the default selected item i.e. for when a user wants to edit their profile etc. I'm told you can't set the selected item by

ddlCountry.SelectedIndex = "United Kingdom"

Instead I'm doing it like this as I don't know what the index is. If there is a better/more efficient way of doing this please let me know

dr = myCmd.ExecuteReader()
            i = 0
            ddlCountry.Items.Add("[Select]")
            ddlCountry.Items(i).Value = "0"
 
            Do While dr.Read()
                i += 1
                ddlCountry.Items.Add(Trim(CStr(dr("Country"))))
                ddlCountry.Items(i).Value = Trim(CStr(dr("Country_Code")))
                If sdefault = Trim(CStr(dr("Country"))) Then
                    ddlCountry.SelectedIndex = i
                End If
            Loop

What I wanted to do was pass in a ref to a DDL and a default item and the function would take care of the rest for me.

MyClass.PopulateCountries(this.DropDownCountries, sDefault)

As suggested by GlenW however I can't seem to reference

Imports System.Web.UI
Imports System.Web.UI.HtmlControls
Imports System.Web.UI.WebControls

when I try to create my populateCountries function there is no dropdownlist in the list of classes (see bold below) -

Public Function PopulateCountries(byRef myDDL as [b]DropDownList[/b], optional byRef sDefault as string = "0") as boolean

I'm sure this can be done, but being a newbie I'm just doing it incorrectly, I truely welcome all guidence

Hopefully the above makes sense

If not let me know

Cheers Al

[GlenW]

Have you referenced System.Web?
If you are writing a class utility that is not part of an asp.net project it won't be referenced automatically.
Just right click on References in solution explorer and then click Add Reference.

[aconybeare]

Glen,
Yes I'm already referencing System.Web, but I can't find these bad boys -

Imports System.Web.UI
Imports System.Web.UI.HtmlControls
Imports System.Web.UI.WebControls

I have an asp.net web project and I've added a class project to it.

[GlenW]

I have an asp.net web project and I've added a class project to it.

Have you added the System.Web reference to the new class project?

[aconybeare]

Glen,

I was just about to reply yes, when I thought I'd better check and it seems not. I've now added it in and the others are now showing okay, yet another school boy error!

Thanks for your help, hopefully I'm on my way now

Cheers Al

[GlenW]

Glad to be of service