Dot Net Code Snippets

Compare DataColumn to null

2011-04-05T12:12:00.000-07:00

Hello all,

Today i got struck in a way how to compare a null value which is coming from database in a dataset........

tried few ways, like this

Object.Equal(ds.Tables[0].Rows[0]["date],null)

ds.Tables[0].Rows[0]["date] == null

Object.ReferenceEquals(ds.Tables[0].Rows[0]["date],null)

but nothing worked ......

at last after a cup of Cappuccino something clicked me & made me feel how stupid my thinking was
because this is DBNull type & I am trying to compare with a different object ……..

so finally it worked like this

value.Equals(System.DBNull.Value)

Hope this helps someone J

Get Text Height & Width

2011-02-09T11:23:00.000-08:00

In many cases we tend to work with dynamic data transaction & data formatting, then we maty need to calculate the width, height & align accordingly w.r.t specific font details etc.,,,,,

I got in to same scenarios, where i need to brush the text on a image & i was breaking my head how to calculated the starting point w.r.t text size, font etc.,,,,,,,,,,
after a long of R & D ; got something which saved me i.e.,

Graphics class (which is a dotnet inbuilt class)

Usage :

Creating a instance

Graphics grpControl = CreateGraphics();

Creating a dummy string value

String minstr =”Minimumvalue”;

Font details I will be working with

Font textFont = new Font("Arial", 16, GraphicsUnit.Pixel);

Now the destination of calculation, graphics Class has a method named MeasureString this is return value of type SizeF

SizeF: It stores the floated points

SizeF sizeDetails = grpControl.MeasureString(minStr,textFont);

Now the return value provide you the Height & width as shown below.

sizeDetails.Height // For height

sizeDetails.Width // For Width

I have seen so many ways to find the string height but this is a best way to find height according to the text font.

Happy Coding :) :)

Maximize child MDI form without ControlBox

2010-10-19T12:26:00.000-07:00

Problem:

When we try maxing the form as maximum mode using control box buttons , then every thing goes fine and it be maximized and can see the toolbar below.

But when we try doing the same with with controlbox = false( this will hide the control box), now if you try making the for to maximize, it will be maximized but it will also hide the toolbar below.

When we hide the control box the form will be maximize to the whole screen ( hiding the system toolbar).

Solution:

Hide the control box on page

Code :

Please paste this code in form load method



In VB

    Me.ControlBox = False



 In C#

    this.ControlBox = false;

Adding text to label using javascript

2010-08-31T14:09:00.000-07:00

While accessing label value from JavaScript, we try like this

document.getElementById('<%= this.lblClientType.ClientID %>').value

But this wont work as it doesn't contain a property called value.

Resolution :

document.getElementById('<%= this.lblClientType.ClientID %>').innerHTML

Reason:

Because when we see the page source, label is been converted to span, where as textbox is converted to input control

asp:label to span control
asp:textbox to input of type "text"

Please provide the comments, if any...

Changing the textbox color dynamically

2010-05-30T12:38:00.000-07:00

Changing the text box styling dynamically using java script.

< script >
function txtBr(Recid)
{
if(Recid==0)document.getElementById ("Text1").style.border ='0px';
if(Recid==1)document.getElementById ("Text1").style.border ='1px';
if(Recid==1)document.getElementById ("Text1").style.borderStyle='solid';
if(Recid==1)document.getElementById ("Text1").style.borderColor ='red';
if(Recid==1)document.getElementById ("Text1").style.backgroundColor='yellow';
if(Recid==1)document.getElementById ("Text1").focus();
}
< /script >
< /head >
< body onload ="txtBr(0);" >
< form id="form1" runat="server" >

< input id="Text1" type="text" runat ="Server" onmousemove ="txtBr(1);" / >

Dynamically creation of web controls and binding Validations Using ASP.NET

2010-05-27T11:52:00.000-07:00

Dynamically creation of web controls and binding Validations Using ASP.NET

Source Code : creatingdynamiccontrols2.zip

Introduction:-
As we know we can bind the controls to our page (aspx) in 2 ways
1. Statically :- Binding the controls while Designing
2. Dynamically :- Binding the controls at runtime
Everyone know how to bind statically but there may be some cases where we need to bind the control dynamically .One of those cases is when our controls are keep on changing like I have a registration site in which the control type may keep on changing then I may need to go for binding the controls dynamically .

Approach:
For binding the controls I need the data what are the controls I want to bind and what is the id to be given and what are the properties to be provided etc.,
This can be provided by 2 ways
1. Using database (This is my approach)
2. Using Xml file
I am creating one example (registration Page) where I am getting the data from the database as a table and based on this table I will be binding my controls to the page as we can see below

My Controls Data from database
ControlText : - Text to be Displayed
ControlType :-
1 – TextBox Control
2 – DropDown Control
3 – DateTime Control
4 – Buttom Control
MaxLength:- Defining the maximum length for textbox
Manditory :- Based On this we will be binding the required field validation
HelpText :- This is used to bind as ToolTip for the control
Source :- Use for binding data source for dropdown controls

Page in which all the controls are generated dynamically
Implementation:
As we know all the server control are under System.Web.UI.WebControls namespace
I will be getting the tabel into a dataset for suppose the name is controlsDataSet
///
/// Method usd to bind the controls
///
///
private void BuldControls(DataSet controlsDataSet)
{
Table table = new Table();
table.Style.Add("align", "center");
// Looping the dataset and get the values
foreach (DataRow datarow in controlsDataSet.Tables[0].Rows)
{
int controlType =
Convert.ToInt32(datarow["ControlType"].ToString());
string controlText = datarow ["ControlText"].ToString();
TableRow newRow = new TableRow();
TableCell textCell = new TableCell();
// Binding the text
textCell.Text = controlText;
newRow.Cells.Add(textCell);
TableCell valueCell = new TableCell();
Control[] cntrlCollection=new Control[4];
// Checking the control Type
switch(controlType)
{
// If TextBox
case 1:
cntrlCollection = this.BindTextBox(control);
break;
// If DropDown
case 2:
cntrlCollection = this.BindDropDown(control);
break;
// If DateTime
case 3:
cntrlCollection = this.BindDateTime(control);
break;
// If Button
case 4:
cntrlCollection = this.BindButton(control);
break;
}
// Adding th controls to the table cell
foreach (Control cntrl in cntrlCollection)
{
if (cntrl != null)
{
valueCell.Controls.Add(cntrl);
}
}
newRow.Cells.Add(valueCell);
table.Rows.Add(newRow);
}
// Adding the table to the main panel
this.pnlControls.Controls.Add(table);
}
Creating controls dynamically is not a big matter but we have bind in such a way that when we are retriving it should not be a problem so we need to give the ids of the controls as below
///
/// Method to bind the DropDown
///
///
///
private Control[] BindTextBox(DataRow datarow)
{
// Retriving the values from the datarow
int controlId = Convert.ToInt32(datarow["Id"].ToString());
int length = Convert.ToInt32(datarow["MaxLengh"].ToString());
bool required =
Convert.ToBoolean(datarow["Manditory"].ToString());
string helpText = datarow["HelpText"].ToString();
string controlText = datarow["ControlText"].ToString();
// Creating the controls array
Control[] controls = new Control[4];
// creating the textbox
TextBox textbox = new TextBox();
textbox.ID = string.Concat(“txt”, controlId);
textbox.ToolTip = helpText;
// Checking the length
if (length != 0)
{
textbox.MaxLength = length;
}
// Adding the textbox to the control array
controls[0] = textbox;
// Checking id manditory
if (required)
{
controls[1] = this.BindRequiredvalidator(controlId,
textbox.ID, controlText);
}
return controls;
}
Suppose I am bind for the name column the textbox id becomes like this
“txt_1” and while saving also we can save accordingly.
So this is the way how to bind the controls and now coming to validation controls (I and using the controls provided my the VS).I am showing you a example where I am bind a validation control to textbox as shown below
private RequiredFieldValidator BindRequiredvalidator(int Id, string
controlId, string controlText)
{
RequiredFieldValidator requiredFieldValidator = new
RequiredFieldValidator();
requiredFieldValidator.ID = string.Concat(“rfv”, Id);
requiredFieldValidator.ControlToValidate = controlId;
requiredFieldValidator.SetFocusOnError = true;
requiredFieldValidator.ErrorMessage = string.Concat(“Enter “,
controlText);
return requiredFieldValidator;
}
For this method I will be passing the Id , ControlId (Like textbox control id) which need to be validated ,controlText used for error messaeges
And after doing all these we can see the paeg with validation controls like this

With Validation controls

Advantages over binding controls statically:
1. Suppose we need to add 10 controls and we are using those statically but now I need to change my control type like a textbox to be changed to dropdown then I need to change all my code once again but this easier while binding controls dynamically.
2. Can bind any validation to any control dynamically.

Association, Aggregation, Composition

2010-05-24T12:34:00.000-07:00

Association, Aggregation, Composition

When we have only one relationship between objects that may be Association. Aggregation and Composition.

In details

Association:

This is relation where each object has it own life cycle , independent and no owner.

Ex:-

Will take a common example of project and developer

A project will be having multiple developers and developer can work for different projects. There is a relationship but both are independent. Both can create and delete independently.

Aggregation:

This is a specialize form of Association where all object have their own lifecycle has ownership on child object and the child object cannot belongs be related to another parent object.

Ex:-

Will take an example of Departments and developers

A developer can be only in one department like dotnet, java etc., but if we delete the Department object still the Developer object exists. This is a “Has- a” relation.

Composition:

This is specialize form of Aggregation and can be called as strong Aggregations

Where the child object has no life if the parent object is deleted, because of this we call this as “death” relationship.

Ex:-

Best example is House and room

A house can have multiple rooms but if we delete the house the child i.e. rooms will also be deleted and has no life.

Difference between XmlNode and XmlElement

2010-04-29T00:02:00.000-07:00

XmlElement is derived from XmlNode (XMLElement is a type of XMLNode) and it is having more functionalists than xmlNode

XmlElement can be used if you are more specific with XML.

Please find all the Node types

Node Types

The following table lists the different W3C node types, and which node types they
may have as children:

Node type	Description	Children
Document	Represents the entire document (the root-node of the DOM tree)	Element (max. one), ProcessingInstruction, Comment, DocumentType
DocumentFragment	Represents a "lightweight" Document object, which can hold a portion of a document	Element, ProcessingInstruction, Comment, Text, CDATASection, EntityReference
DocumentType	Provides an interface to the entities defined for the document	None
ProcessingInstruction	Represents a processing instruction	None
EntityReference	Represents an entity reference	Element, ProcessingInstruction, Comment, Text, CDATASection, EntityReference
Element	Represents an element	Element, Text, Comment, ProcessingInstruction, CDATASection, EntityReference
Attr	Represents an attribute	Text, EntityReference
Text	Represents textual content in an element or attribute	None
CDATASection	Represents a CDATA section in a document (text that will NOT be parsed by a parser)	None
Comment	Represents a comment	None
Entity	Represents an entity	Element, ProcessingInstruction, Comment, Text, CDATASection, EntityReference
Notation	Represents a notation declared in the DTD	None

Node Types - Return Values

The following table lists what the nodeName and the nodeValue properties will return
for each node type:

Node type	nodeName returns	nodeValue returns
Document	#document	null
DocumentFragment	#document fragment	null
DocumentType	doctype name	null
EntityReference	entity reference name	null
Element	element name	null
Attr	attribute name	attribute value
ProcessingInstruction	target	content of node
Comment	#comment	comment text
Text	#text	content of node
CDATASection	#cdata-section	content of node
Entity	entity name	null
Notation	notation name	null

NodeTypes - Named Constants

NodeType	Named Constant
1	ELEMENT_NODE
2	ATTRIBUTE_NODE
3	TEXT_NODE
4	CDATA_SECTION_NODE
5	ENTITY_REFERENCE_NODE
6	ENTITY_NODE
7	PROCESSING_INSTRUCTION_NODE
8	COMMENT_NODE
9	DOCUMENT_NODE
10	DOCUMENT_TYPE_NODE
11	DOCUMENT_FRAGMENT_NODE
12	NOTATION_NODE

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Next Chapter »

Association, Aggregation, Composition

2010-01-07T01:37:00.001-08:00

Association, Aggregation, Composition

When we have only one relationship between objects that may be Association. Aggregation and Composition.

In details

Association:

This is relation where each object has it own life cycle , independent and no owner.

Ex:-

Will take a common example of project and developer

A project will be having multiple developers and developer can work for different projects. There is a relationship but both are independent. Both can create and delete independently.

Aggregation:

This is a specialize form of Association where all object have their own lifecycle has ownership on child object and the child object cannot belongs be related to another parent object.

Ex:-

Will take an example of Departments and developers

A developer can be only in one department like dotnet, java etc., but if we delete the Department object still the Developer object exists. This is a “Has- a” relation.

Composition:

This is specialize form of Aggregation and can be called as strong Aggregations

Where the child object has no life if the parent object is deleted, because of this we call this as “death” relationship.

Ex:-

Best example is House and room

A house can have multiple rooms but if we delete the house the child i.e. rooms will also be deleted and has no life.

ASCII Key values

2010-01-05T04:17:00.001-08:00

Char.	Dec.	hex	Comments
NUL	00	00
SOH	01	01	^A (control A)
STX	02	02	^B
ETX	03	03	^C
EOT	04	04	^D
ENQ	05	05	^E
ACK	06	06	^F Acknowledge
BEL	07	07	^G Bell or tone
BS	08	08	^H Backspace
HT	09	09	^I Horizontal Tab
LF	10	0A	^J Line Feed
VT	11	0B	^K Vertical Tab
FF	12	0C	^L Form Feed
CR	13	0D	^M Carriage Return
SO	14	0E	^N
SI	15	0F	^O
DLE	16	10	^P
DC1	17	11	^Q
DC2	18	12	^R
DC3	19	13	^S
DC4	20	14	^T
NAK	21	15	^U No acknowledge
SYN	22	16	^V
ETB	23	17	^W
CAN	24	18	^X
EM	25	19	^Y
SUB	26	1A	^Z
ESC	27	1B	^[ Escape
FS	28	1C	^\
GS	29	1D	^]
RS	30	1E	^carat
US	31	1F	^_
SP	32	20	Space
!	33	21	exclamation point
"	34	22	double quote html: "
#	35	23	pound or number sign
$	36	24	dollar sign 4
%	37	25	percent
&	38	26	ampersand html: &
'	39	27	single quote/apostrophe
(	40	28	open parenthesis
)	41	29	close parenthesis
*	42	2A	asterisk
+	43	2B	plus sign
,	44	2C	comma
-	45	2D	dash/hyphen
.	46	2E	period
/	47	2F	slash
0	48	30	zero
1	49	31	one
2	50	32	two
3	51	33	three
4	52	34	four
5	53	35	five
6	54	36	six
7	55	37	seven
8	56	38	eight
9	57	39	nine
:	58	3A	colon
;	59	3B	semicolon
<	60	3C	less than html: <
=	61	3D	equal sign
>	62	3E	greater than html: >
?	63	3F	question mark
@	64	40	at symbol
A	65	41
B	66	42
C	67	43
D	68	44
E	69	45
F	70	46
G	71	47
H	72	48
I	73	49
J	74	4A
K	75	4B
L	76	4C
M	77	4D
N	78	4E
O	79	4F
P	80	50
Q	81	51
R	82	52
S	83	53
T	84	54
U	85	55
V	86	56
W	87	57
X	88	58
Y	89	59
Z	90	5A
[	91	5B	left bracket
\	92	5C	backslash
]	93	5D	right bracket
^	94	5E	caret
_	95	5F	underline
`	96	60	grave accent
a	97	61
b	98	62
c	99	63
d	100	64
e	101	65
f	102	66
g	103	67
h	104	68
i	105	69
j	106	6A
k	107	6B
l	108	6C
m	109	6D
n	110	6E
o	111	6F
p	112	70
q	113	71
r	114	72
s	115	73
t	116	74
u	117	75
v	118	76
w	119	77
x	120	78
y	121	79
z	122	7A
{	123	7B	left brace
\|	124	7C	vertical line
}	125	7D	right brace
~	126	7E	tilde
DEL	127	7F	deleting backspace
©	169	A9	copyright html: ©
™	153	99	trademark html: &153; (non-standard)
®	174	AE	registered html: &174; (non-standard)
	na	na	non-breaking space html:

Regards,

Manoj

Difference between Interface and abstract class

2010-01-05T03:08:00.000-08:00

Introduction:

Hi everyone, in this article I will explain what is abstract class & Interface, what their purpose and what is the difference between them.

Back Ground:

Before starting I want to give a brief wind up on something like
1. Class: It is a collection of methods, attributes, Properties etc., all the methods in the class are concrete classes (definition already exists).
2. Concrete Methods: A method which contains the implementation.
EX:-
Public void ConcreteMethod()
{
Console.WriteLine(“Method with Implementation”);
}
3. Abstract Methods: opposite of abstract methods,i.e. method which does not have implementation or body.
Ex:-
Public void AbstarctMethod();
4. As we know both the abstract class and interface cannot be instantiated, because these are used for implementing the inheritance (which mean to derive), because of this we can use these by deriving in our class.

Abstract Class:
Definition: This is a class, which is a combination of both concrete and abstract methods (method without any definition)
A class which contains at least one abstract method
Purpose:
1. Can implement the common functionalities as concrete methods and non common functionalities as abstract methods in the same class.
2. Normal class + additional features of abstract methods.

Interface:
Definition: This is a skeleton representation of a class. It is a pure abstract class.
Purpose:
1. This is used to interact between different modules to specify the methods and there signatures.
2. This is used to define the methods and the signatures types of the method while defining the skeleton, so that I will be easier to implement them.
3. This is used to force the user to implement all the methods declared in the interface.
4. For the implementation of multiple inheritance.

Difference between Interface and abstract class

1. As we see abstract class does not show full abstartion, but interface is a pure abstract class as it has only abstract methods.
2. Can implement the Multiple Inheritance with the use of interface.
3. The modifiers for methods in interface can be only public the modifiers for methods in abstract class can be public or protected.
4. One or more interfaces can be implemented only one abstract class can be extended
5. Only an interface can extend another interface, but class can extend an abstract class.
6. Abstract classes should have subclasses else that will be useless..Interfaces must have implementations by other classes else that will be useless
7. Accessibility modifier (Public/Private/internal) is allowed for abstract class. Interface doesn't allow accessibility modifier
8. An abstract class can contain fields, constructors, or destructors and implement properties. An interface cannot contain fields, constructors, or destructors and it has only the property's signature but no implementation.

Similarities

1.Both the interface and the abstract class can contain zero or nil abstract methods.

2. In both cases all the abstract methods declared should be implemented/extended respectively