I'm trying to add a "How did you hear about us?" field in the cart. Pretty sure I can't do it at checkout unless I have Plus. I tried adding a HTML select menu to the main.cart.items.liquid section, but it just throws an error.
This is the code I'm using right after the closing table element:
<label>How did you hear about us?</label><br>
<select id="how-did-you-hear-about-us" name="attributes[How did you hear about us?]">
<option value="Email"{% if cart.attributes["How did you hear about us?"] == "Email" %} selected{% endif %}>Email</option>
<option value="Phone"{% if cart.attributes["How did you hear about us?"] == "Phone" %} selected{% endif %}>Phone</option>
<option value="In Person"{% if cart.attributes["How did you hear about us?"] == "In Person" %} selected{% endif %}>In Person</option>
<option value="From a Friend"{% if cart.attributes["How did you hear about us?"] == "From a Friend" %} selected{% endif %}>From a Friend</option>
</select>
