contains

Returns whether a list or string contains an item or substring

 boolean contains( mixed haystack , mixed needle )

Returns whether  haystack contains needle.

• If haystack is a string, returns true if needle is a substring.
• If haystack is a list, returns true if needle is a member of that list.
• If haystack is an object, returns true if needle is a value (not a key) of that object.
• Otherwise, will return false.

contains only accepts two arguments. If you wish to use more than two arguments, you can try a more explicit statement like:
{if contains(profile.vars, "var1) || contains(profile.vars, "var2") || contains(profile.vars "var3")}

Examples

{contains('foobar','ooba') ? 'yes' : 'no'}                   = yes 
{contains('foobar','foobari') ? 'yes' : 'no'}                = no 
{contains(['a','b','c'],'b') ? 'yes' : 'no'}                 = yes 
{contains({"foo":"bar","baz":"bap"},"bar") ? 'yes' : 'no'}   = yes 
{contains({"foo":"bar","baz":"bap"},"foo") ? 'yes' : 'no'}   = no

Check if a subscriber is a member of a list, using the Profile object:

{contains(profile.lists,"Main")}

Check if a user has opted out of a specific template by referencing the Public Name:

{contains(profile.optout_templates,"Notifications")}

Display One-Click Signup Link if User Is Not on Certain List

Use Case:

You want to determine if each user is on your ‘Weekly Notifications’ Natural List, and if they aren’t, show them a one-click signup link using the sailthru_lists query parameter in order to enable them to add themselves.

You’ll notice that the contains() function allows you to check if an array contains a certain value(s). You can also use a bang (“!”) to check the opposite, that is, if it’s notin the array.

Zephyr: (Based on example {profile.lists} array value [ "Daily Newsletter", "Sponsored Content", "Breaking News"].)

{if !contains(profile.lists,"Weekly Notifications")}
Click <a href="http://example.com?sailthru_lists[Weekly Notifications]=1>here</a> to sign up to our Weekly Notifications list!
{/if}

Output: Profile Not on Weekly Notifications:

Click here to sign up to our Weekly Notifications list!

(Nothing shown)

Please note that the “else” statement is optional.

Explanation: This script uses an “if” statement to loop through the “lists” array on each user’s “profile” object, which are all the Natural Lists the user is currently a member of. Using the contains() function, we’re able to see if a particular Natural List is included in their lists array, i.e. they’re currently subscribed to that list. Using a bang (“!”) before contains(), the inverse is checked, i.e. if the user is not on that list. If they are not, a prompt is shown to encourage sign up. Using the “sailthru_lists” query parameter, the user is signed up with one click.