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Drupal 7 Webform Cookbook by Douglas Vernon Denny

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Adding custom validation

Our Fictitious Conference organizers have stipulated that a maximum of one presentation proposal is allowed per potential speaker registering via our Speaker Registration form.

The organizers have requested us to put validation in place that will deny a submission where a particular First name, Last name, and Email address combination has previously been submitted, unless the subsequent submission is being made by one of the administrators on behalf of a potential speaker.

Their thinking is that the inclusion of Email address in the check will prevent the possibility of two people with the same First name and Last name being denied a submission because the other person has already made a submission. Another part of the ...

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