How do I use min/max on a nested field in rethinkdb - json

Question

I'm trying to determine the best way to calculate the elapsed time it took for each operation, series of actions. Looking at my example data below, how might I take the min/max for the "actions" array, for each corresponding operation, which includes 'take' and 'throw' actions:
{
"name" : "test",
"location" : "here",
"operation" "hammer use",
"actions" : [
{
"action" : "take",
"object" : "hammer",
"timestamp" : "12332234234"
},
{
"action" : "drop",
"object" : "hammer",
"timestamp" : "12332234255"
},
{
"action" : "take",
"object" : "hammer",
"timestamp" : "12332234266"
},
{
"action" : "throw",
"object" : "hammer",
"timestamp" : "12332234277"
}
},
{
"name" : "test 2",
"location" : "there",
"operation" : "rock use",
"actions" : [
{
"action" : "take",
"object" : "rock",
"timestamp" : "12332534277"
},
{
"action" : "drop",
"object" : "rock",
"timestamp" : "12332534288"
},
{
"action" : "take",
"object" : "rock",
"timestamp" : "12332534299"
},
{
"action" : "throw",
"object" : "rock",
"timestamp" : "12332534400"
},
{
"name" : "test 3",
"location" : "elsewhere",
"operation" : "seal hose",
"actions" : [
{
"action" : "create",
"object" : "grommet",
"timestamp" : "12332534277"
},
{
"action" : "place",
"object" : "grommet",
"timestamp" : "12332534288"
},
{
"action" : "tighten",
"object" : "hose",
"timestamp" : "12332534299"
}
}
Expected output:
{
"operation" : "hammer use",
"elapsed_time" : 123
},
{
"operation" : "rock use",
"elapsed_time" : 123
}
I'm still new to rethinkdb and trying to get a hang for it. So far, I've come up with the following query to pick the specific records, i'm interested in, from the table:
r.db('test').table('operations').filter(function(row) {
return row('actions').contains(function(x) {
return x('action').eq('take')}).and(
row('actions').contains(function(x) { return x('action').eq('throw') })
);
});
I'm still trying to figure out how to aggregate the results by taking the min/max of the timestamp and subtracting them from each other.
I hope there's enough detail there to get an idea for the goal at hand. Let me know otherwise. Any help greatly appreciated.

Answer 1

Well, nobody tugged on this so I had to solve it without any help. Took a bit longer but finally figured out how. Here's the pseudocode for finding min/max on the nested fields above, and elapsed_time:
r.db('test').table('operations').filter(function(row) {
return row('actions').contains(function(x) { return x('action').eq("take") }).and(
row('actions').contains(function(x) { return x('action').eq("throw") })
);
}).map(function(doc) {
return {
operation: doc('operation'),
min: doc('actions')('timestamp').min(),
max: doc('actions')('timestamp').max(),
elapsed_time: doc('actions')('timestamp').max().sub(doc('actions')('timestamp').min())
}
})