Dropdown Won't show first Item

Dropdown Won't show first Item


I have a dropdown box

It will not show the first Item on the list.  It does however run the code for that list item

Here is the page when it loads

Here it is when the dropdown looks like after it it is selected

If PROGRAMS is selected the screen goes back to looking like the first picture

Help me out


Hi Andrew,

Could you please explain what is the action VendorDDOnChange is doing which you have called on the onChange event of the dropdown.



Does the variable has a default value or is being assigned before the render of the page or do you have duplicated identifiers on your dropdown?

I use the variable to set the criteria for a second dropdown.  The vendorDDonchange it used to refresh the entity source for the second dropdown

First dropdown finds the vendor.  The second dropdown find products from that vendor using the variable I'd from the first

Hi Andrew,


  • What do you have in the x.y Expression of the Dropdown?
  • What is the Data type of the variable Vendor?
  • Does it have a default value?

Things you should try:

  • Remove the second dropdown and the OnChange Event handler from the first dropdown. Does it still have the same behaviour?



The x.y expression is the name of the suppler. Getvendors.list.current.supplier.name

The datatype of the variable is an Integer.  This corresponds the the suppler number and it does not have a default value

I have removed the second dropdown and the behavior still exists.  The first record in the dropdown will not show

Hi Andrew,

Without knowing your datamodel or your aggregate Getvendors it's not easy. :)

If I had to guess, I would say that there ara some Vendors that are not Suppliers and you are doing a With or Without join on the aggregate. Thus, the supplier name is coming up empty.

If that is not the case, can you share at least screenshots of your datamodel and of the joins that you are doing in the aggregate?



Hi Andrew

I would say that José is probably 99% correct in this.

See this small example: https://eduardojauch.outsystemscloud.com/PreviewInDevices/?IsMobilePreview=True&DeviceName=Smartphone&URL=/MobileApp/Screen1?_ts=636408453337554319

I have two combo boxes in it.
The source list is the Users entity. The variable being used is the USER.EMAIL.
The variables associated are empty.
The user User1 does not have an email (value is empty "").
IN the aggreate used in the second combo, I removed the first name (Eduardo Jauch).

In the first combo box, the first user is selected since the beginning, and the email variable is set to its email. If I try to select User1, because the email is empty, it returns to Eduardo Jauch

In the second combo box, nothing is show from the beginning, and if I try to select it, the selection is reverted to empty.

I think this is exactly the behaviour you are having, no?

So, check that for the first item in your list/aggregate, Programs, Vendor.Vendor is really defined, like José said.

Eduardo Jauch