Example to show how to use a query to get the key value tags for the user's subscribed items using Steamworks.NET.

SteamUGC-KeyValueTagsQuery.cs

/*
Keys can map to multiple different values (1-to-many relationship).
Key names are restricted to alpha-numeric characters and the '_' character.
Both keys and values cannot exceed 255 characters in length.
Key-value tags are searchable by exact match only.

Taken from https://partner.steamgames.com/documentation/ugc
*/


// OnSteamUGCQueryCompleted should be set up the same way OnSubmitItemUpdateResultCallResult currently is

var subscribedItemIDs =  new PublishedFileId_t[(int)SteamUGC.GetNumSubscribedItems()];
SteamUGC.GetSubscribedItems(subscribedItemIDs, (uint)subscribedItemIDs.Length);

var query = SteamUGC.CreateQueryUGCDetailsRequest(subscribedItemIDs, (uint)subscribedItemIDs.Length);
SteamUGC.SetReturnKeyValueTags(query, true);
SteamUGC.SetReturnOnlyIDs(query, true);

var handle = SteamUGC.SendQueryUGCRequest(query);
OnSteamUGCQueryCompleted.Set(handle);


void OnSteamUGCQueryCompleted(SteamUGCQueryCompleted_t pCallback, bool bIOFailure)
{
    if (pCallback.m_eResult != EResult.k_EResultOK)
    {
        return;
    }
    
    /*
    TODO: Look into why pCallback.m_unTotalMatchingResults exists (pagination?)
    It could mean we cannot use resultIndex to get the ID from subscribedItemIDs like we currently do below
    */
    
    var handle = pCallback.m_handle;
    
    for (var resultIndex = 0; resultIndex < pCallback.m_unNumResultsReturned; resultIndex++)
    {
        var itemID = subscribedItemIDs[resultIndex];
        var keyValueTags = new Dictionary<string, List<string>>();
        
        var numerOfKeyValueTags = SteamUGC.GetQueryUGCNumKeyValueTags(handle, resultIndex);
        
        for (var keyValueTagIndex = 0; keyValueTagIndex < numerOfKeyValueTags; keyValueTagIndex++)
        {
            string key;
            string value;
            
            // Given the info at the top of the file 255 as the size for both key and value should work?!
            if (!SteamUGC.GetQueryUGCKeyValueTag(handle, keyValueTagIndex, out key, 255, out value, 255))
            {
                continue;
            }
            
            List<string> values;
            if (!numerOfKeyValueTags.TryGetValue(key, out values))
            {
                values = new List<string>();
                numerOfKeyValueTags[key] = values;
            }
            
            values.add(value);
        }
        
        /*
        We now have and can use:
        - itemID
        - keyValueTags
        */
    }
    
    SteamUGC.ReleaseQueryUGCRequest(query);
}