BuddyPress.org

For a new group, leave group_id empty.

To get members of a specific group, use groups_get_group_members.
Found in buddypress\bp-groups\bp-groups-functions.php
Review the function to get all the parameters.
Example:

$args = array( 'group_id' => 99 ); 
$group_members = groups_get_group_members( $args );
var_dump( $group_members );

Use these functions in your custom code after the user is added and their ID exists:
Add user to a group: groups_join_group( $group_id, $user_id );
Make user active on the site: bp_update_user_last_activity( $user_id );

Try this hook: do_action( 'groups_promote_member', $group_id, $user_id, $status );

Found in: function groups_promote_member

File: buddypress\bp-groups\bp-groups-functions.php

Hi,

It looks like bp_get_current_group_id() doesn’t manage to guess the Group ID out of the Group’s URL when using Ajax. That’s probably because your plugin is adding extra characters into the URL like the short language name.

You could try filtering bp_uri when doing Ajax to replace these extra characters with nothing.

eg:

function myshanai_wpml_ajax_fix( $path ) {
   if ( wp_doing_ajax() ) {
      $extracharacters = ''; // replace with the language short name.
      $path = str_replace( $extracharacters, '', $path );
   }

   return $path;
}
add_filter( 'bp_uri', 'myshanai_wpml_ajax_fix' );

These are the forums for BuddyPress.
BuddyBoss is a fork of BuddyPress and does some things differently.
You may have better luck asking the folks at BuddyBoss.

But here is a hint, instead of unset, use the filter:
apply_filters( 'bp_rest_group_settings_forum', $fields, $group_id );
Found here:
buddyboss-platform\bp-groups\classes\class-bp-rest-group-settings-endpoint.php

I found a workaround to avoid the creation of duplicate activities for the same cpt post on updating.

function me_activity_parse_args_filter( $args = array() ) {     
    if ( !empty( $args['type'] ) && $args['type'] == 'new_your-cpt' ) {
                $activities = bp_activity_get(array(
                        'max' => 1,
                        'filter' => array(
                        'action' => 'new_your-cpt',
                        'secondary_id' =>  $args['secondary_item_id'],
                        ),
                ) );
                if (count($activities['activities'])==0) { // The cpt post doesn't have activity yet, so we set the group information
                        $args['component'] = 'groups'; // You could set this as 'component_id' in bp_activity_set_post_type_tracking_args
                        if ( !empty(bp_get_current_group_id()) ) $args['item_id'] = bp_get_current_group_id();
                        if (empty($args['content'])) $args['content'] = ' ';  // To make sure content filter applies afterwards 
                } else { // Activity already exists
                        $args['type'] = false; // Delete duplicate activity
                }
    }     
    return $args;
}
add_filter('bp_after_activity_add_parse_args', 'me_activity_parse_args_filter',10,1);

@joeobi15 uisng group_id parameter you can list all members of a group https://codex.buddypress.org/developer/loops-reference/the-group-members-loop-bp_group_has_members/

Here is another approach. I dont like it at all because you cannot check a custom post type (you dont have the activity object). But it works.

function me_filter_bp_activity_item_id_before_save( $item_id ) { 
    if ( !empty(bp_get_current_group_id()) ) $item_id = bp_get_current_group_id();
    return $item_id ; 
}; 
         
add_filter( 'bp_activity_item_id_before_save', 'me_filter_bp_activity_item_id_before_save', 10, 1 );

BTW: The value 1 seems to be the default blog ID.

In this thread @imath explains that:

Custom Post Type Support for Activity

I’m also interested in solving this problem (I think the number 1 is actually the user id). The only way I could find is to use bp_before_activity_add_parse_args filter:

function me_activity_parse_filter( $cpt ) {
    if ( $cpt['type'] == 'your_custom_type' ) {
        $cpt['item_id'] = bp_get_current_group_id();
    }     
    return $cpt;
}
add_filter('bp_before_activity_add_parse_args', 'me_activity_parse_filter');

However, if the cpt post is updated a new activity is created instead updating the original one…

Note that in bp_activity_set_post_type_tracking_args I have
'component_id' => 'groups',

Maybe @imath can help us to solve this issue.

This should work

add_action( 'bp_core_activated_user', 'join_group_on_signup');
function join_group_on_signup( $user_id ){
    $group_id = 13; //change it to the group ID of your choice
    groups_join_group( $group_id, $user_id );
}

If you have phpmyadmin, you could try manipulating the database tables.
Make a full backup of your database first.
Then open the _bp_groups table, find the row with the id of the group and change value of the creator_id field to your id.
Then open the _bp_groups_members table, find the row with the group_id and the is_admin field where the value will be “1” – and change the value of the user_id field to your id.

If that does not work, then there is some code on your site that needs to be removed.
Check your theme/functions.php and plugins/bp-custom.php if it exists.

You are correct. For a private group try this which uses a different hook:

function schene_promote_group_member( $user_id, $group_id ) {
    $group_member = new BP_Groups_Member( $user_id, $group_id );
    $group_member->promote( 'admin' );
}
add_action( 'groups_membership_accepted', 'schene_promote_group_member', 99, 2 );

Use this hook which is available right after they join.
do_action( 'groups_join_group', $group_id, $user_id );

Try this in your theme/functions.php or in bp-custom.php:

function schene_promote_group_member( $group_id, $user_id ) {
    $group_member = new BP_Groups_Member( $user_id, $group_id );
    $group_member->promote( 'admin' );
}
add_action( 'groups_join_group', 'schene_promote_group_member', 10, 2 );