Returns a list of your groups.
It is possible to search for a single group using a pipe delimited hierarchy string. If your group structure is Level 1 -> Level 2 -> Level 3, where 1 is the parent of 2 and 2 is the parent of 3, then you can retrieve Level 3 by specifying q[hierarchy_eq]=Level 1|Level 2|Level 3.
If you want to filter on the Groups endpoint, you have to use a special filter when querying the attributes related to the group hierarchy. Instead of querying using parent_id_eq, you'll want to use ancestry_cont and actually pass the parent_id to that.
So, instead of doing a GET request to https://secure.fleetio.com/api/v1/groups?q[parent_id_eq]=1234, you'll want to do a GET request to https://secure.fleetio.com/api/v1/groups?q[ancestry_cont]=1234.
Note that this will return all children, grandchildren, etc. of a particular group ancestor, not merely the direct descendent.
If you want to filter by the names of the ancestor Groups, you can do a GET request by passing a String filter for ancestry_names, making sure to escape any spaces as %20.
For example, https://secure.fleetio.com/api/v1/groups?q[ancestry_names_matches]=Test%20Parent%20Group.
Or, if you don't know the exact name, you can do a partial match like, https://secure.fleetio.com/api/v1/groups?q[ancestry_names_cont]=Test%20Parent.