Wednesday, November 18, 2020

asp.net online notes

1. What is asp.net? 

        Asp.net frame work is a part of the .NET  frame work used to create a dynamic website, web application and web services. It is a server-side technology that uses all .NET compatible languages such as c#, vb.net etc, which are compiled to micro soft intermediate language (MSIL) asp.net uses server control to develop a rapid and interaction interactive application in an easy way.

2.What is the difference between web site and web application

Web site

        In a web site, you cannot add multiple projects

-        There is no project file. All the files in a folder structure are automatically included in the site

-        The website is easy to create and display

-        You can use different .NET  languages or a single website, such as vb.net pages and c# pages can be used on the single website.

-        You cannot establish dependencies on a web site.

 

Web application

-        In a web application, you can add multiple projects

-        It has a visual studio project file stores information about the project like as the list of files that are included in the project, and any project to project references.

-        You can established dependencies in a web application

3. What is the difference between client side and server side validations?

        Client side validations work at the client end with the help of scripting languages such as java script or vb script.

       On the other hand, server-side validations work at the server end with the help of programming languages like c#,vb.net etc

        Server validations work when you submit or send data to the server

4. What is MVC

        MVC is the frame work used to create web application. The web application base builds on Model view controller pattern. Which separates the application logic from UI, and the user will be controlled by the controller.

5. asp Vs asp.net

        Key difference between them is that asp is interpreted as scripts are used, whereas asp.net is compiled because of these pages using .NET languages

6.what is the extension for asp.net pages

.aspx

 Structure of an asp.net page

List of the important elements of an asp.net page

-Directive

-Code declaration blocks

-asp.net controls

-code render blocks

-source code comments

-server code include directives

-Literal text and html tags

Directive

        A beginning of a directive is marked with the characters

<%@ and end of a directive is marked with the characters %>

A directive can appear anywhere within a page

Page directive

        You can use a page directive to specify the default programming language for a page. For example, you would use the following page directive

<% page Language =”c#” %>

        You can enable tracing for a page by including the following directive

<% page trace =”true” %>

<Script runat=”server”>

Sub page_load

Dim strtracemessage as String

Trace.warn(“page_load event executing”)

setTracemessage =”hello world”

trace.write (“the value of strTrace message is “& strtracemessage)

end sub

<script>

<head> <title> Trace.aspx</title>

</head>

<body>

<h2> Testing page trace </h2>

<% trace.warn(“Rendering page content1” %>

</body>

</html>

 Code declaration blocks

        A code declaration blocks contains all the application logic for asp.net page and all the global variable declaration, subroutines and functions.

        We can declare subroutines and functions only within a code declaration block

        If no language is specified in a page, the language defaults to visual basic.

Asp.net controls

        Controls are small building blocks of the GUI which include text boxes, buttons, check boxes, list boxes and numerous other tools.

Code render blocks

        If you read to execute code with the html or text content of your asp.net page, you can do so within code render blocks. The two types of code render blocks are inline code and inline expressions.

        In line code executes a statement or series of statements. This type of code begins with the characters <% and ends with the characters %>

        In line expression on the other hand, display the value of a variable or method (this type of code is shorthand for response.write )

        The <%=….. %> displaying expression is an equivalenet of the embedded code block that contains only the response.write (…) statement. It is the simplest way to display information, such as a single string, an int variable or a constant.

<%@ page language =”vb”%>

<html>

<body>

<form id=”form1” runat=”server”>

<%= DateTime.Now.ToString()%>

</form>

</body>

</html>

        Remember that the displaying expression can not be used in the attributes of the server controls. It is because .NET framework directly compiles the whole expression instead of the displaying content as the value to the attribute.

Server-Side Comments

        The asp.net web forms compiler completely ignore everything within the <%...%>

 

Server-side Includes SSI are directives that are placed in HTML page and evaluated on the server while the pages are being served.

Literal text and HTML tag

        The literal control is used to display text that is it renders static text on a web page without adding additional HTML tags.

Data Sources in asp.net

        The data source control provides data in the controls without complex coding. The actions like insert, update, delete, and sort is possible using the data control. There are various data source controls in asp.net. The model allows users to create user data source control which can internet with various data sources.

        The different data sources used in asp.net are as mentioned below

1.linqDataSource: The language integrated query in an asp.net web page is possible using the mark-up. The insert, update, select, delete commands are supported. Filtering sorting and paging of the data are possible.

2.Object data source: The user can work with the objects using the object data source.

3.sqldata source: User can work with a micro soft SQL server. Oracle OLEDB and oracle databases. The sorting, filtering, paging of the data is possible using the data source.

4.Access data source: working with a micro soft access database is possible using the data source.

5.XML data source: user can work with the XML file when the hierarchical structure needs to be used as a data source.

6.Sitemapdata source

        Site navigation data


Asp.net features 

Asp.net    Asp.net is a web application framework developed and marketed by micro soft to allow programmers to build dynamic web sites.

          The principal design features of Microsoft .net framework is

-         Interoperability

-         Portability

-         Security

-         Language independence

-         Type safety

-         Memory management

1.Interoperability: is the ability of code to interact with code that is written using different programming language.

2.portability: portable class libraries can help you reduce the time and costs.

3.Security: The code can access are restricted based on this evidence associated with the code and its identity.

4. Language independence: It is possible to use .net from many programming languages because they have all agreed on some standards

5. Type safety: This prevents ill-defined casts, wrong method invocations, and memory size issues when accessing an object.

6.Memory management: automatic memory management is one of the services that the common language runtime provides during managed execution



Master pages

        Master pages allow you to create a consistent look and behavior for all the pages (or group of pages) in your web application.

        A master page provides a template for other pages, with a shared layout and functionality. The master page defines placeholders for the content, which can be overridden by content pages. The output result is a combination of the master page and the content page.

<% master %>

<html>

<body>

<h1> standard header form master page </h1>

<asp:contentplaceholder id =”cph1” runat =”server”>

</asp:contentplaceholder>

</body>

</html>

        The master page contains a place holder tag <asp:content placeholder> for individual content

The id =”cph1” attribute identifies the placeholder, allowing many placeholders in the master page.

<% page master page File –“master1.mastr”>

<asp: content  contentplaceholder id =”cph1” runat=”server”>

<h2> individual content </h2>

<p> paragraph 1 </p>

<p> paragraph 2</p>

</asp:content>

        A master page is the design layout of the web page, which helps to  standardize the look and feel for web pages in the application, the master page contains all common reusable interface part of all asp.net web pages.

-master the page provides a template for standardization

- In one application we can have multiple master pages

-It has place holders for the content, which can be overridden by the web page.

-master page comes with .master extension

- script language, header, footer all are placed on the master page

Content place holder – a place for web page control, in page

Asp: content   has a property called content placeholder id to map with place holder

        In real-time application development you may have a requirement where you need to change the master page dynamically at run time depending on user role, permission, region, etc

Nested master page

        When one master page references another master page as its master, that’s called a nested master page. One master page can have multiple levels of another page references though there is no architectural limitation but having for many levels of the master page may be considered as bad design

 Grid View control

        The grid view control displays the values of a data source in a table. Each column represents a field, while each row represents a record. The grid view control supports the following features

-        Binding the data source controls such as SQL data source

-        Built-in sort capabilities

-        Built-in update and delete capabilities

-        Built-in paging capabilities

-        Built-in row selection capabilities

-        Dynamically ser properties handle events and so on

-        Multiple key fields

-        Multiple data fields for the hyperlink columns

-        Customize appearance through themes and styles

 

Displaying empty data

        Suppose that there is no data in the data base table or no results are returned from the data source then you can display user-friendly message in a grid view that there is no record available

-        Empty data text

-        Empty data template

The grid view control supports the following types of fields

Bound field: how to display the column and its value.

            Department-ID, employee id

Command field

    Command the field is used to perform edit, delete, update, cancel, and select operations.

Template field

    You can customize the user interface and all validation logic to the fields

Altering item template: the content of every alienate row

Edit item template: user edit the records.

Footer template: content displayed at the column footer

Header template contents of the column header

Insertion template: insert a new data item

Row data-bound template

    Rowdatabound event is used when you want to modify the appearance of individual rows in a grid view 

 Object data source control

        Object data source control uses reflection to expose and call the appropriate methods of a business object to select, insert, and update data.

Different operations supported by object data source control

Selection: which retrieves data

Sorting: sorting elements

Filtering: filtering expression

Updating: that performs updating

Deleting: that perform deleting

Inserting: set the insert method to business object method that perform insertion

Old value parameter: the old value is the original value of the field when the page first loads

Select method: select the contents

Select parameter: number of possibilities for selecting parameters

Sort parameter name sort

Type name: used for specifying dependent name, identifies the name of the class works with

Update method: number of columns updated in the data storage


Update parameter:  your parameter values and list of values will automatically be updated

Enable paging: 10 records on a page at a time

Select count method: select count number of rows that matches a specified criterion

Select row index parameter

Object data source control uses reflection to create instances of business objects and to call methods on them to retrieve, update, insert, and delete data. 

 

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