Grails domain class, String field TEXT and LONGTEXT

In a Grails domain class, how do I set the constraint for a String field so that its MySQL column type is TEXT or LONGTEXT?

So far my best approach is to set the constraint's size:

myTextField(size:0..65535)

which results in TEXT

myTextField(size:0..2147483646)

results in LONGTEXT (2147483646 = 2^32 / 2 - 1 - 1)

Is there a cleaner way to specify the size? Basically I want the full range of TEXT or LONGTEXT without having to hardcode a bunch of size values.