Unique values from object class

How do i filter the object class to only keep the unique values?

Ex. I have a object class with “Members” the person in Members can have several roles, in my unique object class i want it to list only one of every person. I have seen it been done before by @Thomas Hesselberg, but i dont remember how.


If you have Person and Members, where Members is having multiple entries per Person (with diffent Roles): for example, it holds “John, Administrator”, “John, Employee”, “Paula, External”, “Lisa, HR”, “Lisa, Employee”.

To get the unique persons in the Members datasource, read the Persons data source with filter Person.ID exists in Members.Person. Now, the Persons data source holds John, Paula and Lisa.

Hope that helps.

Of course you can do it that way, thanks!

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This is all fine if you want to find a unique set of objects by looking up their ID in a one to many or many-to-many relationship. In my case, I want to list all unique working titles (sting values on an attribute) for all employees, so I can present them in a filter. In SQL I would have used SELECT DISTINCT on the “employee title” column.

Looping all employees and adding titles to a runtime data source while making sure no duplicates are added is extremely slow. What I ended up doing was to add a coded component with the following code:

function add_selected({ title }, index) {
    return unique.actions.add_title({ title }) // This should return a Promise
        .catch(console.error); // Keep the catch to handle potential errors

// Run add_selected for each unique title
function addAllTitles(uniqueResourceTypesWithTitles) {
    // Create an array of promises by mapping over uniqueResourceTypesWithTitles
    const promises = uniqueResourceTypesWithTitles.map((titleObj, index, array) => {
        return add_selected(titleObj, index, array);

    // Wait for all promises to resolve
    Promise.all(promises).then(() => {
        console.log('All uniqe titles added successfully.');
    }).catch((error) => {
        console.error('An error occurred', error);

function getUniqueResourceTypes(employees) {
    const uniqueResourceTypes = new Map();

    employees.forEach(employee => {
        const { emloyee_title } = employee;
        if (!uniqueResourceTypes.has(emloyee_title)) {
            uniqueResourceTypes.set(emloyee_title, emloyee_title);

    // Convert Map to an array of the values (emloyee_title in this case)
    const result = Array.from(uniqueResourceTypes.values());

    // Convert each value into a dictionary with a "title" key
    const titledResourceTypes = result.map(type => ({ title: type }));

    return titledResourceTypes;

// Get the unique resource types as dictionaries with "title" keys
const uniqueResourceTypesWithTitles = getUniqueResourceTypes(unique.data.employees.get());

What the code does is to read out all unique employee titles and populate a runtime object “Unique stings” with only one attribute called “Sting” I use the Unique String object class for to create “dynamic enumerations” that I use for filters in the UI.

Ugly but it works. Please suggest a better way if it exists.
I would love to see something like SELECT DISTINCT built in to Appfarm.

(You might ask why I don’t use enumerations for this kind of data but in my case these data is returned by API from another source, so I have no control on the string values used for employee titles)

Other related topics here on the forum : How to list unique values - #3 by Preben
Output only unique object classes in a many-to-many relationship data