I am using vk.com api and I need to get all groups of city. I have found groups.search method (https://vk.com/dev/groups.search). But groups.search method require a 'q' string parameter (substring which must be part of the group name), which is bad for me, becouse the group name does not matter in this case.
I'm working with VK API for 4 years. The main thing you need to know about parsing any data from VK is that any search allow you to get just first thousand of results.
Group searching, people searching - you'll find only first 1000 items. It's fixed rule. Also there is no difference about number of found results (you can see, for example, 123456789 found groups. Scrolling opportunity will be finished as soon as you reach 1000th item)
So, basing on that fact the one decision you have is to parse all symbols in their different positions and groups as 'q' parameter so you will have to get a lot of groups. 'city_id' and 'country_id' can be found in source of element for their selecting if you need.