The METHOD Attribute of the FORM Tag

Now that you know about creating checkboxes, radio buttons, and submit buttons within a FORM tag, we need to look once more at the METHOD attribute of the FORM tag.

Here is the code from the example from the previous section:

<title>Example Form</title>

<p>Choose your favorite type of pet:<br />
<input type="radio" name="pets" value="dog" /> Dog<br />
<input type="radio" name="pets" value="cat" /> Cat<br />
<input type="radio" name="pets" value="bird" /> Bird</p>

<p>Choose your favorite color:<br />
<input type="radio" name="colors" value="red" /> Red<br />
<input type="radio" name="colors" value="green" /> Green<br />
<input type="radio" name="colors" value="blue" /> Blue</p>

<input type="submit" value="Submit Me, Please" />

And here is the example displayed.

Make a choice from each group of radio buttons in this example and click the submit button as shown in the following illustration:

Form Choices

Look in the location bar of the browser (where the URL for the current page is displayed), as shown in the following illustration:

Query String

You will notice that a question mark (?) has been added to the end of the URL for the current page, and see so-called "name-value pairs" appended onto the end of the URL following the question mark (in the example above, the name-value pairs are "pets=cat" and "colors=red").

When a FORM is submitted, the various form elements in the FORM may be converted into name-value pairs derived from the values of their NAME and VALUE attributes, e.g. NAME=VALUE. When there is more than one name-value pair in a FORM, the ampersand (&) character is inserted between the pairs. These name-value pairs may be looked at by a script analyzing a FORM.

The text comprised of the question mark followed by name-value pairs in the web browser's location bar is called a "query string".

When a FORM has its METHOD attribute set equal to "get" (the default value), clicking on the submit button causes the browser to extract all of the chosen name-value pairs from the FORM; these name-value pairs are then converted into a query string which is appended onto the end of the URL in the web browser's location bar.

When a FORM has its METHOD attribute set equal to "post", the form information is submitted in a manner which does not need further explanation at this time. With method="post", the submission process is invisible to the user, as you may observe in this example.

If you are utilizing a pre-made CGI script, you will be directed to use either method="get" or method="post", depending upon the script. If you are creating HTML forms without knowing much about the script processing the form, you should use method="post" whenever there is form information which needs to remain "secret" (e.g. not displayed in the location bar), such as password information, etc; the rest of the time, you should use method="get" (which is the same as not setting the METHOD attribute at all).

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