# Unique values from object class

**URL:** <https://community.appfarm.io/t/unique-values-from-object-class/775>\
**Category:** Ask the community\
**Tags:** app-data\
**Created:** [October 18, 2023, 3:42pm UTC](https://community.appfarm.io/t/unique-values-from-object-class/775 "2023-10-18T15:42:36Z")\
**Posts on this page:** 1\
**Showing post:** 4

<div class="post-metadata">

**Author:** ![lbj](https://dub1.discourse-cdn.com/flex013/user_avatar/community.appfarm.io/lbj/32/82_2.png) [@lbj](https://community.appfarm.io/u/lbj)\
**Post date:** [March 13, 2024, 1:14pm UTC](https://community.appfarm.io/t/unique-values-from-object-class/775/4 "2024-03-13T13:14:34Z")

</div>

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:

```auto
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());
addAllTitles(uniqueResourceTypesWithTitles);

```

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.

 ![image](https://europe1.discourse-cdn.com/flex013/uploads/appfarm/original/2X/9/945ebe80b763b30d1ba2665d58dfada1c8a310c6.png)  
 ![image](https://europe1.discourse-cdn.com/flex013/uploads/appfarm/original/2X/7/72863bc19f08456413254f3e42a8e9d3b50ccbb9.png)

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](https://community.appfarm.io/t/how-to-list-unique-values/530/3)  
[Output only unique object classes in a many-to-many relationship data](https://community.appfarm.io/t/output-only-unique-object-classes-in-a-many-to-many-relationship-data/424)

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