If you want to populate certain form fields with data from the request URL then you can do this using what we call dynamic content tags. There are various built-in tags available, but the one we’ll need to retrieve data from the URL is {data key="NAME"}.

Say you want to send a hidden “source” and “campaign” field to Mailchimp for which the data is in the URL of the page your form is on. To fill the fields with these values, use {data key="source"} and {data key="campaign"} as your field values.

Example form mark-up

	<label for="mc4wp_email">Email address: </label>
	<input type="email" id="mc4wp_email" name="EMAIL" placeholder="Your email address" required />

	<input type="submit" value="Sign up" />

<!-- Notice the value="{data key="xxx"}" attributes of the following fields -->
<input type="hidden" name="source" value="{data key="source"}" />
<input type="hidden" name="campaign" value="{data key="campaign"}" />

The plugin will automatically try and find a “source” and “campaign” field in the URL. If the fields are not present, the plugin will replace the placeholders with an empty string.

Setting default values

You can set a default value for when the specified data is not found by adding a default attribute to the tag.


{data key="NAME" default="Some value"}