Derived Controls and Maintaining State

Sometimes you need to extend controls. One way is to add properties to a control. I wanted to use a checkbox in a item template in a gridview. I wanted the checkbox to fire an event similar to the row command event. Unfortunately the checkbox does not fire a rowcommand event or has a commandname/command argument.

The solution I came up with was to a add an extended checkbox with a commandargument property. This is straight forward. Just include this in your App_Code folder.


Public Class GridviewCheckBox
Inherits CheckBox
Private _CommandArgument As String
Property CommandArgument() As String
Get
Return _CommandArgument
End Get
Set(ByVal value As String)
_CommandArgument = value
End Set
End Property


Protected Overrides Function SaveViewState() As Object
Dim arrState(2) As Object
arrState(0) = MyBase.SaveViewState()
arrState(1) = Me.CommandArgument 'that is my custom property to be saved
Return arrState
End Function

Protected Overrides Sub LoadViewState(ByVal savedState As Object)
If Not savedState Is Nothing Then
Dim arrState() As Object = savedState
Me.CommandArgument = CType(arrState(1), String)
MyBase.LoadViewState(arrState(0))
End If
End Sub



End Class

In order for your property to be persisted across postback you need to override the LoadViewState and SaveViewState functions.

To use the control in your page register it at the top of the page (or in the web.config)
<%@ Register Namespace="CustomControl" TagPrefix="cc" %>


This can now be placed in the item template of a gridview and fire off an event when checked

<cc:GridviewCheckBox runat="server" ID="chkCheckList" AutoPostBack="true"OnCheckedChanged="chkCheckList_CheckedChanged" Checked='<%# eval("deleteflag") %>' CommandArgument='<%# eval("CheckListID") %>'/>



This can be handled in the code behind and you can use Naming container properties of the checkbox to access the parent gridviewrow and gridview to get the datakey values.


Protected Sub chkCheckList_CheckedChanged(ByVal sender As Object, ByVal e As System.EventArgs)

Dim chk As CustomControl.GridviewCheckBox = CType(sender, CustomControl.GridviewCheckBox)
Dim wsBW As New wsBusinesswise.BusinessWise
Dim CheckListID As Integer

Dim row As GridViewRow = CType(chk.NamingContainer, GridViewRow)
Dim gvw As GridView = CType(row.NamingContainer, GridView)

CheckListID = gvw.DataKeys(row.RowIndex).Values("CheckListID")

End Sub

Breaking on Handled exceptions

Sometimes errors get trapped and nothing gets done with them so it can take a little while to find where the error is being swallowed. When in debug mode you can set VS to break on any exception even if is in a try catch statement. Go to Debug > Exceptions and you get the window below. If you tick the "Thrown" checkbox for Common Langauge Runtime Exceptions, VS will break on .net exceptions.



I haven't used this in detail so I don't know how useful this is or whether it works when calling a web service.

Dataset Visualiser in debug mode

This is a nice tip for looking at datasets in debug mode. Sorry the images are so small. Step into your code after the dataset has been filled and put the name of the dataset in the watch window like below.



If you look at the dataset in the watch widow you will see a little magnifying glass in the right of the row. Click on that and you get an option for a dataset visualiser. The dataset now pops up in a grid making it easy to look at. There are also XML and Text visualisers.

What's in a Title?

Here's a scoop - check out the daft things users type when given a 'Title' textbox next to Forename and Surname ones. The importance of data entry validation shows itself...

I want to find the single Chief that we have and shake his hand. How!

(null) 95499
MR 52971
Mrs 31700
Miss 16545
Ms 9052
Dr 388
Mr & Mrs 265
Mother 59
Mr and Mrs 38
wife 38
mum 34
Mr/Mrs 31
Sister 30
PARTNER 26
FATHER 25
Husband 23
Emp 22
XXXX 22
123 18
- 17
M/s 17
Mr&Mrs 16
Daughter 15
Mis 14
M 14
a 13
Mrs 12
Brother 11
Mr/s 11
Son 11
Test 10
Mrs (Wife) 10
Nr 10
Mr 10
xxx 9
tba 8
Rev 8
f 8
H 8
n/a 8
MR / MRS 7
Friend 7
D 6
Dad 6
MR+MRS 6
Revd 6
Prof 6
PARENTS 6
Revd Dr 5
RMN 5
Mr Mrs 5
Mt 5
Mrs (mum) 5
Mrs/Mr 5
c 5
Canon 4
Ms 4
g 4
Mrs & Mr 4
Mr. & Mrs. 4
Playcarer 4
t 4
xx 4
y 4
TBC 3
q 3
r 3
Revd Canon Dr 3
Reverend 3
RGN 3
Mr. 3
MR OR MRS 3
Mrd 3
mre 3
Mrs & Mrs 3
office manager 3
matron 3
Me 3
j 3
fd 3
gg 3
Director 3
Customer Rep 3
e 3
. 3
213 3
b 3
Boyfriend 3
Childcare Worker 2
Baron 2
Baroness 2
0 2
(Friend) 2
(mother) 2
Title 2
miss 2
EN 2
Doctor 2
Drs 2
dtrdrtd 2
Dr & Mrs 2
CLEANER 2
Fr 2
gf 2
hj 2
Joiner 2
k 2
LORD 2
Kitchen Manager 2
Lady 2
MIISS 2
Mirs 2
Mr + Mrs 2
Mr (Dad) 2
Missq 2
Office Supervisor 2
n 2
nursery assistant 2
nMr 2
Mrs` 2
MSS 2
Mr,Mrs 2
Mrt 2
mrr 2
Mra 2
Mrage 2
MRS / MR 2
Mr. & Mrs 2
RMN/RGN 2
s 2
Receptionist 2
Playleader 2
ON FILE 2
uygyguy 2
vv 2
The Revd 2
The Revd Dr 2
tdtrd 2
yguy 1
yuiy 1
The Ven 1
Tile 1
Title 1
ton 1
trtMs 1
tt 1
u 1
unknown 1
uyb 1
uyguyg 1
WAITER 1
vbv 1
vdfs 1
Working 1
x 1
xcv 1
tbq 1
t Miss 1
Tania 1
Test bb 2 1
Test PB 1
tfyf 1
The Rev 1
Spare 1
ss 1
Stacey 1
STEP FATHER 1
Step-father 1
Stores Manager 1
SUPERVISOR 1
support worker 1
ooo 1
p 1
p.t waitress 1
PARENT 1
Playleader/Co-ordina 1
Plumber 1
Production Editor 1
Rev'd 1
QA Manager 1
PCO 1
SAMEMRS 1
SAsa 1
school 1
sd 1
sdf 1
SIR 1
Rob 1
rrt 1
Ruby 1
ruir 1
RHR 1
REVEREND CANON 1
rewq 1
Revd Prof 1
Mr, 1
Mr, Mrs 1
Mr./Mrs. 1
Mr.Mrs 1
Mr/ Mrs 1
Mr//Mrs 1
MR S 1
MR& MRS 1
Mr and Mrs Stokes 1
MR BONSER 1
Mr Cox 1
Mr Krys 1
Mrs and Mr 1
Mrs and Mrs 1
Mrs Emilia Sobon 1
Mrs Rai 1
Mrs Ruth 1
Mrs Stacey 1
MRS WEBB 1
Mrs, 1
Mrs. 1
Mrs/ Mr 1
Mr` 1
Mr/Mrs Biggs 1
Mr/Mrs/Miss 1
Ms (mum) 1
Ms, 1
Ms. 1
Mrsd 1
Mrsel; 1
MRSS 1
Mrs (sis) 1
NO ONE 1
NONE 1
Not Advised 1
NAN 1
New 1
NK 1
oijoi 1
Nrs 1
My 1
Mz 1
Mn 1
Monika 1
Mother-in-Law 1
Mr &Mrs 1
Mr ( husband) 1
Mr (Grampa) 1
Mr (Husband) 1
Mr (Son) 1
Mr * Mrs 1
Mr / Miss 1
Mr 3 1
Mr /s 1
Misses 1
Minn 1
M s 1
M.D. 1
Messers 1
Mf 1
Mfrs 1
Mg 1
Miaa 1
Miis 1
Laird 1
Laura 1
Lesley 1
li 1
Logistics 1
kjh 1
kkijdhh 1
kpok 1
Kylie 1
Lynn 1
Karl 1
MA 1
Major 1
MANAGERESS 1
Managing Director 1
Joss 1
hjHJ 1
hjj 1
Jamie 1
Janine Smith 1
jhgfhfg 1
jij 1
jim 1
i 1
Ian 1
IE test 1
IEMRS 1
ii 1
iijio 1
ij 1
ijo 1
IN LAWS 1
ineMrs 1
ITHMR 1
iuhuihu 1
IV12 4SUMs 1
gfhjg 1
head of department 1
hg 1
hgfhgf 1
Hh 1
ghffghfgh 1
GIRLFRIEND 1
Gp Capt 1
Gran 1
grandma 1
GRANDMOTHER 1
GRIFM 1
fdeb 1
fdfsdf 1
fdsaf 1
fdxfdxfd 1
fg 1
fgbfgb 1
fgccf 1
fh 1
Finance Manger 1
Financial Controller 1
fitter 1
Fleet Maintenance 1
FMRS 1
gbed 1
Gemma 1
EMPLOYEE 1
fbf 1
Cllr 1
Club Secretary 1
COUSINE 1
coverer 1
Cptn 1
DO NOT USE 1
dafgfdg 1
dd 1
ddd 1
Debbra 1
Denneyu 1
Dennis 1
Deputy Matron 1
Deputy Playleader 1
Design Editor 1
df 1
dfbv 1
DICKINSONMRS 1
Dr / Mrs 1
Driver 1
ennet RoadMrs 1
er 1
Escort 1
efv 1
Eleonor Calciati 1
emma 1
MISS 1
(fiance) 1
(flatmate) 1
(Parents) 1
(wife) 1
,MBMNV 1
? 1
` 1
`MR 1
|Mr 1
|Mr & Mrs 1
000 1
00123 1
0018 1
01407 740035Mr 1
02380 704478Mr 1
036 1
07801 245060Mrs 1
0788 263 6231Mr 1
0MRS 1
1 Miss 1
1192 1
231 1
255 1
28 7128Mr 1
3 1
5 1
716329 1
7803854349Mrs 1
7875 294758Mrs. 1
BDE 1
BiMr 1
bob 1
1234 1
147 1
189 1
2 1
204 1
aa 1
Admin Manager 1
Airport Supervisor 1
alison 1
Assistant Editor 1
Assistant Manager 1
AUNT 1
Aunty 1
Chris 1
Business Dev Manager 1
Bright 1
B IN LAW 1
Canon Dr 1
Capt 1
CARER 1
Centre Coordinator 1
CentreCoordinator 1
CEO 1
Chef 1
Childcare coordinato 1