.NET 101

Introduction

.NET is basically an interface for a single programming language. MSIL, However languages can be written to be compliant with MSIL and thus usable with the .NET framework.

Using System

Most Basic Project setup

Hello World

Using System.Text

String / StringBuilder

Strings are immutable (non appendable) thus very inefficient when there are multiple changes to the value.

My habit I’ve tried to develop is anytime I am using += more than once or twice I use a StringBuilder.

Array / ArrayList

Array List had Dynamic Resisizing

:Add method so you don’t have to keep track of last index.

:Remove/ RemoveAt / RemoveRange Method

:Sort

Also properties: Count

Using System.Web

Web Controls (except Data grid) and Data Binding

All controls are Server Controls when dropped off the toolbox. This means they are very useful, unless you want to do some client side processing to avoid trips to the server. If this is your desire then you need to use handbuild HTML clientside controls.

All Controls inherit from Control Class (Buttons including regular/radio/checkboxes inherit from ButtonClass which inherits from Control Class.

Basic, most commonly used Control Class Properites.

Anchor (Anchors when window resized), BackColor, Dock(Docks to edges of window), Enabled, ForeColor, Height, Left, Name, Parent, Right, TabIndex, TabStop, Tag(a spot to store additional data associated with the control, Often used to hold valid or not), Top, Visible, Width

Labels

.Text is most commonly used Property

TextBox

Warning if you use Multiline = True, then it changes when it renders from an HTML TextBox to a HTML TextArea which changes some of the available events. Specifically maxlength property is inaccessible.

Buttons / ImageButtons / Link Buttons

RadioButtons

SelectedItem most commonly used property

ComboBox / DropDowns

SelectedItem most commonly used property

ListItem and ListItemCollection are two key objects for interfacing with List Controls

**DataBind must be in !Page.IsPostBack if later events to avoid rebinding everything which clears your values that you think you have.

Here is a list of some of the other controls that we won’t be going over today, but are available.

ListBox, ListView, GroupBox/Panel, RichTextBox, StatusBar, ImageList, TabControl, Validators, Calendar

Using System.IO

StreamReader

The Base class is the StreamReader, but the functionality of the TextReader and XMLReader are very similar.

Key code to remember: stringreaderExample.Peek()>-1

1||Red||E

2||Blue||W

3||Green||E

Using System.XML

Key code: SelectNodes

Xpath is like a folder system -- 10 Second intro to Xpath

/ represents absolute path, // relative path, * wildcard, //@ for attributes, [1], selects first , count( ) returns count, starts-with ( )..

Sample XML

<?xml version='1.0' encoding='ISO-8859-1'?>

<catalog>

<cd country='USA'>

<title>Empire Burlesque</title>

<artist>Bob Dylan</artist>

<price>10.90</price>

</cd>

<cd country='UK'>

<title>Hide your heart</title>

<artist>Bonnie Tyler</artist>

<price>9.90</price>

</cd>

<cd country='USA'>

<title>Greatest Hits</title>

<artist>Dolly Parton</artist>

<price>9.90</price>

</cd>

</catalog>

State / Request / QueryString

Key code: String s = Request.QueryString["Name"];

Getting an item passed through can be grabbed in C# or Javascript. The most common way is to grab in C#

vVariable = Request["Variable "]

then get in javascript alert(‘<%=vVariable%>’)

In order to hold a value through multiple postbacks putting an variable in to “ViewState” is often the simplest way to go.

Application level state can be controlled through global.asax

Session Level state can be controlled using Session[“anyvarname”]

Debugging

Debugger

Trace

Trace.Write(strTemp)

Trace=true

Response

Can still use, but must be perfect syntax

Framework

Project

More Complex Project Setup

The best architecture for multiple developer .NET projects is utilizing SourceSafe.

On a server you have the original copy of the Project. Whenever you work on the project you check it out and work locally on your machine. (The whole project is running on your machine, not just the file. – Thus you must ‘Get Latest Version’ of the entire project regularly to ensure you have updated code for the pages that you are not checking out.) Then when you are done you check it back in which mouse it back to the Server. You can then do a build on this Server to update this server. This server can be your Live Server, in which case you are done….or for an extra layer of comfort, this can be your Dev machine. The Live Server is just like any other machine/user who checks never checks out stuff. Because you can do a ‘Get Latest Version’ of only a few files or do a ‘Get Latest Version’ of the whole project you can very safely update small sections of your website.

One more hint : Don’t start page names with numbers – Confuses C#

References/ Web References (add web.mail to windows form)

Other

Copy Project

You must use this to move a project, copy and paste in Windows Explorer doesn’t work.

If you are not using SourceSafe this is the simplest way to move files back and forth. However there is no project management. You simply overwrite the Live Server.

Bulk Comment/Uncomment

Go to Definition / Reference…

Region Blocks

# region Mail and IO functions / # endregion

Design View Format – Align lefts, Make same size, snap to grid

+= works in c# and vb.

Using System.Net

HttpWebResponse

Key objects – HttpWebRequest, HttpWebResponse.

Sample Code

HttpWebRequest HttpWReq = (HttpWebRequest)WebRequest.Create(strURL);

HttpWebResponse HttpWResp = (HttpWebResponse)HttpWReq.GetResponse();

string stringResult;

using (StreamReader sR = new StreamReader(HttpWResp.GetResponseStream()))

{

stringResult = sR.ReadToEnd();

sR.Close();

}// Insert code that uses the response object.

HttpWResp.Close();

Using System.Data / System.Data.SqlClient

Data Access

ADO.NET is very similar looking to ADO at first glance but very different the more your find.

Both use the connection and command object, and the recordset is relatively similar to the dataset object. That said…

SqlClient is faster than OldDb for SqlServer.

Connection object – very similar to the ADO connection. 99% of connection strings work for ADO.NET

The command object is similar but with enhancements. The command object is exposes the Reader object which cannot be directly instantiated. Thus the only way to utilize is through the Reader’s Methods

ExecuteNonQuery (Returns nothing),

ExecuteScalar (returns a single string)

ExecuteReader (a forward-only, read-only DataSet) is through the Command object.

ExecuteXMLReader which returns an XML document

A dataset is a disconnected set of data and can represent tables or multiple tables. It is usually built through the dataAdapter’s object fill method.

More Controls

DataGrid, DataList, Repeater

**DataBind must be in !Page.IsPostBack if later events to avoid rebinding everything which clears your values that you think you have.

AutoGenerateColumns vs. Bound Columns

Formatting for datagrid, BackColor, Font, CellPadding, CellSpacing, Wdth, Horizontal Align.

Styles – HeaderStyle, FooterSytle, ItemStyle, AlternatingItemStyle

It is possible to specify these bound columns programmatically, but it’s ugly and ton’s of code.

Formatting for bound columns, HeaderText, FooterText, HeaderStyle/FooterStyle/ItemStyle, DataFormatString

DataList

Slightly faster than DataGrid, but requires hand building of columns.

More Data

DataSet

Disconnected like Recordset, but can hold multiple Tables.

DataAdapter

Used to populate DataSet

Stored Procedure

Command.CommandType = CommandType.StoredProcedure;

Command.ComandText = “spTblTest”;

Parameters

Use to properly input Text field data into databases.

SqlParameter spParam = new SqlParameter("@sName", SqlDbType.VarChar);

spParam.Value = "blank1";

spCommand.Parameters.Add(spParam);

Using System.ServiceProcess

WebServices

Create webservice .asmx page using prewritten code

Create call to it by adding web reference and

localhost.Service1 webServ = new localhost.Service1();

webServ.Url = "http://localhost/Net101Service/Service1.asmx";

You should be able to click on the url and see the available services.

Event Handling

Server Side

DataGrid – Auto

Most Common double click button/control and event function automatically build, simply add event code

Must utilize !Postback… in PageLoad to avoid binding rebinding on events and losing your event args.

AutoPostback Controls Non-Auto Postback Controls

Button Checkbox (list)

DataGrid Listbox

Image RadioButton(list)

Link DropDownList

DataList TextBox

Client Side

Javascript just like asp

To add javascript event to a server side control add the following to code behind

txtItemDes.Attributes.Add( "OnKeyUp","checklen()");

A few Other C# objects worth remembering

Convert

Math

DateTime

ListItem / ListItemCollection

Practice Exercise.

1. Create 3 strings –Math, Physics, English
2. Use StringBuilder to create another sbClass – History
3. Combine into a single string strAll;
4. Create string array strArrClasses and split strAll into it.
5. Create RadioButtonList rblClasses and bind alClasses to it.
6. Add button btnGo and grab selected radio rblClasses.SelectedItem.ToString(); (watch postback)
7. Insert new row into Database with
8. Create a DataGrid dgClasses
9. Get Datareader from table tblTest where tblTestName is in our previous arrayList and bind to dgClasses
10. Format Header (fix names in SQL) and make every other row grey and the header row black with white lettering.
    
    
11. Extra for fast kids, add a dropdownlist above radio buttons called ddlDate
12. Create a string array with max of 3 ;s
13. Assign index 0 today’s date (hint: DateTime object) – index 1 Tomorrow’s date, index 2 Yesterday’s date.
14. Bind array to ddl and when Go is clicked add this item as second Column.