ReathinkDB:Query multiple tables with chaining - rethinkdb

Question

In RethinkDB I am trying to chain multiple queries to multiple database tables. The idea is the same as stored procs for traditional dB's. Basically I query all the users connected to a device and then for each users try to get the rules attached from a rules table.
Here is a gist of the ReQL query I am writing. But forEach does not work as it wants a write query and not read and also do() is failing. Any suggestions?
const get_distance = function(location){
const final_location = 500;
return r.expr(500).sub(location);
};
​
const run_rule = function(device,distance){
return r.db('locationtracker_development').table('customer_details').filter(function(cust){
return cust("deviceId").contains(device);
}).pluck("userId").forEach(function(userName){
//TODO Work on each user
return r.db('locationtracker_development').table('user_rules').filter({'userId':userName('userId')});
});
};
r.do(get_distance(100)).do(function(dist){
return run_rule('gXtzAawbc6',dist);
});

Answer 1

I have gotten it resolved with help from the Slack Channel of RethinkDB.
Here is the code :
const get_distance = function(location){
const final_location = 500;
return r.expr(500).sub(location);
};
const run_rule = function(device,distance){
return r.db('locationtracker_development').table('customer_details').filter(function(cust){
return cust("deviceId").contains(device);
}).coerceTo('array').map(function(doc){
return doc('userId');
}).do(function(userIds){
//return userIds;
return r.db('locationtracker_development').table('user_rules').
getAll(r.args(userIds),{index:'userId'});
});
};
r.do(get_distance(100)).do(function(dist){
return run_rule('gXtzAawbc6',dist);
});
Basically the objects returned needs to be coercedTo and Array and then using map and do functionality we can achieve querying multiple DBs.