Combobox Dropdown vs. Combobox Droplist in EPDM Data Cards

I ran into an interesting challenge while helping a customer through an evaluation of EPDM.  He wanted cascading style pull downs on his data card.  This, in itself, is not a big deal, but he ran into a problem that I had not considered before.  If he selected values in his pull down menus and then went back to the driving pull down to change its value, it would leave old information in the other fields creating an impossible combination of values.


  • The setup:
For testing, I created four lists:
The first list, “List A-C” will be the driving list.  If I choose “A” from that list, a second pull down will show me the contents of, “List A1-A3.”  If I choose “B” from the first list, the second pull down will show me the contents of, “List B1-B3.”  If I choose “C” from the first list, the second pull down will show me the contents of, “List C1-C3.”  Cool, right?
This is what it looks like on the data card:
From the first list I chose “A”
Now, from the second list, I am only able to select items in “List A1-A3”
Life is good!!
  • The problem:
Now, let’s say I go back and change the value of the first pull down to “B.”
As you can see, the second pull down is still displaying the old value of “A3” which really should not be a possible value if the first pull down is now set to “B.”  Grrrrrrrrrrr…


  • The solution:
The problem isn’t in the lists, it’s actually in the type of pull down fields I selected to be used on the data card.  The type I used in the above example is called “Combobox Dropdown.”
A Combobox Dropdown allows me to not only select from a list, but it also allows the user to type text into the field.  There in lies the rub.  Once you have made a selection in the second pull down, EPDM sees it as just plain text and maintains that value even if you change the value in the first pull down.
What I should have used, to get the desired result, was a “Combobox Droplist.”
When I use “Combobox Droplist” this is what get:
As you can see, when I changed the selection in the first pull down from “A” to “B” the second pull down became blank.  When I select on the second pull down, I can choose from “List B1-B3.”  A “Combobox Droplist” does not allow the user to manually type in text.  You can only select from what is in the list and that is why the second pull down gets cleared when you change the value of the first.  For the customer, this is a much more desirable behavior and eliminates the possibility of a bad combination.
I look forward to hearing any questions or comments on this topic.  So, please feel free to post comments below, or to email me at blog made the assumption that you already know how to create cascading style pull downs in the data card editor.  Stay tuned as I will expand on this topic to show how you can create these types of pull downs. Thanks for taking a look at today’s blog.  Until next time, I wish you happy data management. 

Stephan Hess

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