We've a large site running Drupal 7 with OG, Flag, Rules, etc.
OG uses a subscription model where you have to confirm you want to join a group (or leave a group) so we've decided to move to a Flag system that then uses rules to add (or remove) that user from the group.
All works great, except the site is already live and we have a lot of members in groups already, which obviously Flag doesn't recognise.
Is there a way to force Flag to check if a group subscription exists already?
I seem to understand from your question, that you're looking for a way to flag the existing members of an OG group.
If that's what you want, then a possible approach to make this work, is to process the results of a VBO enabled view via Rules, whereas your rule performs 2 Rules Actions:
For more details, have a look at the tutorial "How to process the results of a VBO enabled view via Rules?".
PS: if this is NOT what you want, by using this approach (anyway) I believe your question about "Is there a way to force Flag to check if a group subscription exists already?" became obsolete ...
Guess what, if for some reason (such as this one), you can't get it to work with the prior answer, then you may want to try an approach which is like "the other way around". Read on for more details on that approach ...
Start with creating an extremely basic Rules Component, which includes whatever Rules Conditions you might need (if any), and with a Rules Action to flag (using the Flag module) a user, whereas you specify the user to be flagged as a parameter for that Rules Component. FYI: this is really like a getting started with Rules ...
Create a view of your existing members of an OG group that you want to be flagged. Maybe you already have such view that you can use. Then transform that view into a view that uses Views Bulk Operations, and use the technique documented in "How to use Rules to create a custom bulk operation for a VBO view?".
In doing so, you'll then be able to use Rules Components (using the Rules module), in which you can then include the required logic to flag a single user with your flag. If you wonder how to create such Rule that would fit your VBO view (ie that you can use in it), then use this link ...
Even though one may think "Hm, is it really that easy?", it happens that after you created a Rules Component and try to use it in a VBO view, that Rules Component cannot be selected as an operation to be enabled in your VBO view. If that happens, and you wonder what it would take to try to make it show up anyway (in the VBO view), then use this link ...
