How to filter one list from another to display a shorter list on form.

Hi, you could do it using the UID variables.

First, you need to have your companies data have a certain form. You need an array that has multiple objects. Something like this :

[{displayKey: "company1", returnKey: "company1"}, {displayKey: "company2", returnKey: "company2"}]

Then, use this data in the companies dropdown, Display key is displayKey and Return key is returnKey.
Have the value of your companies dropdown be assigned to a UID variable (ex: companiesValue).
Then, create a UID variable (let's say it's called controller) that will have a function that will filter the contacts data depending on the selected companiesValue. The value of the controller variable will be something like this:

return {
filterDataDependingOnCompanySelected: function(companySelected) {
$data.contacts.filter(function (contact) {
contact.company = companySelected;
});
}
};

Or create a list that can be used in a dropdown (through displayKey, returnKey). Now, all you need to do is call "controller.filterDataDependingOnCompanySelected(companiesValue)"and you will get a list of contacts that are part of the company. You can always change how you filter the contacts if your data differs.

Hope this helps,
Dumitru