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ASP ( Active Server Pages )

                 Index              

 

Form handling in Asp 

Form and request object in ASP

Forms in web pages are very common. We can have signup forms to login forms and many other types of forms in our web pages. Through forms users submit data to the server or interact with the site. This is the way server gets user entered information for further processing. Through a login form when we submit our user id and password, the data reaches the server and is checked against stored user id and password for validation.

Form design is a front end job so html is used to generate different form components to get formatted data from the user. Different form components are used based on the type of data to be entered by the user. For example if the user has to enter the state name of USA then it is better to ask the user to select the state name from a drop down list box (showing the list of states) than asking the user to enter the state name in a input text box.

Once the user submits the form, data processing is done at server side and here we will be using validation at server side scripting language to handle the data. We will learn how to process the form data using ASP ( VBScript ). Such jobs can be handled by other scripting languages like PHP, Perl, JSP etc.

In the form html code we will specify to which page the data is to be send by using action attribute and we will also specify method to tell the form the way data is to be posted. There are two methods to post the data, one is GET and the other one is POST method. Here is the code for basic html form.
                  

<form name=f1 method=post action=file_name.asp>
… form components
</form>
         

From the above code we can see the method is specified as post and the action is pointing to file_name.asp. So here we will receive the data of the form in file_name.asp page for processing. To handle the form data in receiving page ASP request object is used. Next we will learn how to use
 

Get method and request object to collect data in ASP

As we have seen in ASP form basics, there is an Request object to handle or receive data of a form in the action page ( page specified in form action attribute ). We will learn how to get data using request object and how the data is posted through query string in GET method.

In GET method data of the form is passed through query string in name and value pairs. The data is separated from the file name by question mark( ? ) and between each pare of name and value ampersand ( & ) symbol is used to separate. Here is the example how in the GET method data is transferred.
 

You can see in the above query string the form data is kept after the file name and the question mark ( ? ) . Then name and value pairs are used and they are separated by ampersand ( & ). This is the way data is posted using URL or the address bar of the browser window.

Collecting data using Request object in ASP
Once the form is submitted data is available to the page indicated at the action attribute of the form. Here we have to use Request.QueryString to get the value of the data field. To get the name entered by the user in name field here is the code

Dim name
Name=Request.QueryString(name)

Here we declared name as a variable for in the present script and then used Request object to collect the data of the name field. Now name field data is available to the variable name. Same way other data can be collected by using query string.

Here is the code of a form

<form method=get action=my_file.asp>
Your Name<input type=text name=name><br>
Age (years)<input type=text name=age size=3>
<input type=submit value='Submit Data'>
</form>

Here is the asp code inside my_file.asp file to collect the query string data

Dim name,age
name=Request.QueryString("name")
age=Request.QueryString("age")
Response.Write ("Welcome " & name & " You are " & age & " Years Old")
 

We can get all the query string data displayed by using for each loop as they are stored as name value pairs. Here is the code. Note that we are not using any individual form component name to collect the data.
 

Post method of form data handling by request object

In POST method of sending form data to processing page is more used than GET method. In POST method data entered inside the form is passed to action page by using HTTP header. The main difference visible here is that data is not passed through URL as a query string in user address bar (like GET method). Here is the form code for method object.

<form name=f1 method=post action=file_name.asp>
… form components
</form>
 

In POST method data can be collected by using request object of ASP. Here is the code

Here my_var is a declared variable and city is the form component name where city name is entered by the user. Now the value entered by the user is available at variable my_var

Like in the Get method we can also loop through and display all the name value pairs associated in POST method of form submission. Here is the code

But this is not a good practice of allowing all variables to initialize as this can be exploited to pass unwanted variables into the script.
 

Collecting checked radio button value of a HTML form in ASP

Radio buttons in a form in ASP is used to collect user's choice. Here radio button is used when user has to select one of the many options presented. For example we want the visitor should say the mode of transport he select while traveling. Here one of the four options is to be decided by the visitor so we can use radio button here. As a part of the form component radio buttons can be used along with other components of a form. We will discuss here only the handling of radio button in a form and collecting the radio button value through ASP.

A group of radio buttons will have same name but different values. In a form there can be any number of groups of radio buttons but each group of buttons will have same name.

We will try here with one group of radio button giving the visitor to select one choice but same can be extended to more than one group of radio buttons. Here is the code to display a group of radio buttons inside an html form.
 

As we submit the form the value of the selected radio button will be available at the action page and we can collect the value of this radio button like this.
 

Dim mode
mode=Request("t1")
Response.Write " Mode of Transport is " & mode
 

This way the selected mode of transport will be available for further processing.

Getting the checked values of checkbox Array of a form in ASP

Checkbox are shown to visitors to get the opinion on a fixed value. Sometime the visitors may have to submit more than one choice out of a group of options so here checkbox can be shown to the visitors. For example we can ask the visitor to submit what are the games they play and we can show a list of games. Visitor may select one or more ( or may select all ) games by clicking the checkboxes. Here choice can be more than one ( In case any one to be selected out of the list then radio button is to be used ) so checkbox is the best option. We will learn how to collect the checked values of the form checkbox inside ASP for further processing. Here is the html form with checkboxes.
 

Here we have used t1 as common name for all the checkbox with different values so they will be treated as a group of checkbox. Once the form is submitted then the values of the checked checkboxes will be available to the action page and can be collected like this.
 

We have used t1 as the common name so all the values of the checkbox for which the visitor has checked will be available as Request("t1") as comma separated values. So in the above code the variable mode value will be consisting of all checked values separated by comma.
 

So now let us split the string to get the array of checked values.

Now we will loop through the array by using for for loop and UBound function to print out the checked values of the checkboxes.