Description
The URL Params WordPress Plugin allows you to access URL parameters in the Query String of the URL.
The plugin even allows you to specify a default value in the shortcode if the parameter isn’t set, so if you want to say “Hello, FirstName” and FirstName isn’t set, it could say something like “Hello, Friend!”
To specify a backup url parameter, enter multiple parameters seperated by commas. The plugin will check for each parameter, in order, until a matching one is found and return that. Failing finding any of the parameters you listed, the default will be returned. For example, you can specify [urlparam param="FirstName, First, name" default="Friend" /] to check for FirstName, and if not found, then First, if not found, then name, and if not, then just return “Friend”.
If the parameter is a date, you can also specify the dateformat option using a PHP friendly date format, for example [urlparam param="somedate" dateformat="F Js" /]. Note that PHP only returns dates formatted in English regardless of locale settings.
This is great if you have personalized links, like from Infusionsoft or Keap, as it lets you personalize a landing page with a persons name.
You can also use this to pre-fill out form fields for folks based on the querystring. For example, if their first name is passed in the URL, your landing page can greet the viewer by name and pre-fill their name on a form.
Usage
Use the shortcode urlparam with the optional parameter of “default”. For example [urlparam param="FirstName" /] or [urlparam param="FirstName" default="Friend"/].
For conditional content use [ifurlparam][/ifurlparam]. For example, [ifurlparam param="FirstName"]Hey, I know you, [urlparam param="FirstName"]![/ifurlparam] would greet known visitors, but display nothing to users without a FirstName in the query string.
If you want to show content when a value does NOT exist, you can set empty in [ifurlparam]. For example [ifurlparam param="FirstName" empty="1"]Welcome to the site, visitor![/ifurlparam] would greet visitors without a FirstName in the query string, but display nothing for visitors with FirstName in the query string.
If you want to show content only to visitors with a specific value in their query string, you can set is in [ifurlparam]. For example, [ifurlparam param="FirstName" is="Bob"]Hi, Bob![/ifurlparam], would only greet visitors with the FirstName param set to Bob.
If you want to have urlparam return an HTML attribute, for example to use in pre-setting the value of input or hidden input fields, pass in the optional attr parameter. You might set a value attribute for an input field like so: <input type="text" name="firstname" [urlparam attr="value" param='FirstName']> or you might set a src attribute for an image tag like so: <img [urlparam attr="src" param='imgurl']>
If you want urlparam to return an entire HTML tag, for example in creating an input field, pass in the optional htmltag parameter. For example, [urlparam htmltag="input" type="text" name="firstname" id="first" attr="value" param="FirstName" default="Bob" /] will produce something like <input type="text" name="firstname" id="first" value="Bob" />
Security
To help protect your site against Reflected Cross Site Scripting, we sanitize output with esc_html() which prevents any HTML tags from being passed in and displayed. This would prevent someone from passing in javascript, for example, and having it execute on your site.
Starting in the WordPress 4.2.3 security auto-update, you can no longer include shortcodes in HTML attributes. Previous to this WordPress update, you could set a field value like this: <input type="text" name="firstname" value="[urlparam param='FirstName']">. Now you have to set it like this: <input type="text" name="firstname" [urlparam attr="value" param='FirstName']> or [urlparam htmltag="input" type="text" name="firstname" attr="value" param="FirstName" /]. If you are still using this shortcode the old way, unfortunately, WordPress simply won’t process the shortcode and will return the full shortcode text unprocessed.
To prevent unprivileged users (like Contributors) from using this shortcode to have privileged users (like Admins) accidentally execute arbitrary javascript via HTML attributes (like onclick, onmouseover, etc), html tags and attributes are sanitized.
If you do need have a need to set certain sanitized tags or attributes, at your own risk, you can manually allow these from the URL Params options page under Settings.