Practical PostgreSQL

Using Cookies with LXP

LXP has the ability to both set and retrieve cookie values. The LXP tag to set a cookie is <setcookie>, and the LXP tag to display a cookie value is <putcookie>.

Setting Cookies

The setting of a cookie must happen before any content is sent from the Apache server. This is because the cookie is included in the headers that precede the actual output of the requested document.

A special construct exists for this type of scenario, called the initialization dock, which is defined with <dock type="init">. This tag must be the first LXP tag following the <lxp> tag in your document. Within it, you may use the <setcookie> tag. Here is the syntax for opening an initialization dock:

<lxp>
  <dock type="init">

Once the dock is open, you may set cookies with the following syntax:

<setcookie name="cookie_name" value="cookie_value"
           domain="cookie_domain" path="cookie_path"
           expires="cookie_expiration" />

When the dock is closed with </dock>, the cookies will be set, and content following the closing dock tag will be sent to the client.

Only the name and value attributes are required to set a cookie. Supplying an empty value has the effect of deleting the cookie.

Setting an explicit domain is helpful in specifying the detail of a domain the cookie should be accepted for (e.g., www.thelinuxreview.com, versus .thelinuxreview.com for all subdomains). Similarly, the path attribute specifies a URI path to maintain the cookie for (e.g., path="/app/").

If the expires attribute is omitted, the ...