Using “seen” on a trail in KRL

Question

I want to have a trail that helps keep track of values I want to persist for users. If a user has not entered their name, I want to display a form for them to enter their name to use for lookups.

I want to be able to check if the name is on the trail. If the name is on the trail then display the data for that user. If the name is not on the trail then I want to display a form for them to enter their name.

I am looking for some help on how I would accomplish this. It was suggested to encode a struct as json and pushing that on to a trail and then search for it. Some direction on how this would be done would be helpful. Would I use the following?

if seen ent:user_data with <regexp> then {
   <get and show data>
} else {
   <show form to user>
}

Answer 1

If you just want to save a simple string for later then you can do something like the following using an entity variable

in the pre block retrieve saved name from entity variable:

savedName =  ent:userName || "";

in the postlude save or clear the entity variable:

set ent:userName userName;
clear ent:userName;

Example app => https://gist.github.com/722849

Example bookmarklet => http://mikegrace.s3.amazonaws.com/forums/stack-overflow/example-persistant-trail-bookmarklet.html

Example run on http://example.com results

• first run on example.com

• after clicking submit

• reloading the page and running the app again

• clearing trail by running on yahoo.com

• running app on yahoo.com before saving name or after clearing

Note: When you want to save something else like an age, you can just use a different entity variable like

ent:userAge

The sky is the limit. ; )