RethinkDB: How to get data from dictionary field and transform them to lists - rethinkdb

Question

I have objects that have a following structure:
[
{
'record': 1,
'tags': [1, 2],
'data': {
'1': 10,
'2': 15
}
},
...
{
'record': 1,
'tags': [3, 4, 5],
'data': {
'1': 100,
'2': 150
}
}
]
How can I get distinct lists of data: [10, ..., 100] and [15, ..., 150] to process each of them?
Thanks

Answer 1

If all data have same key, I proposed this map-reduce process.
.map(function(doc) {
return doc('data').keys().map(function(key) {
return [key, [doc('data')(key)]]
}).coerceTo('object')
})
.reduce(function(left, right) {
return left.keys().map(function(key) {
return [key, left(key).setUnion(right(key))]
})
.coerceTo('object')
})
With your data set, we have:
r.expr(
[
{
'record': 1,
'tags': [1, 2],
'data': {
'1': 10,
'2': 15
}
},
{
'record': 1,
'tags': [1, 2],
'data': {
'1': 19,
'2': 100
}
},
{
'record': 1,
'tags': [3, 4, 5],
'data': {
'1': 100,
'2': 150
}
}
]
)
.map(function(doc) {
return doc('data').keys().map(function(key) {
return [key, [doc('data')(key)]]
}).coerceTo('object')
})
.reduce(function(left, right) {
return left.keys().map(function(key) {
return [key, left(key).setUnion(right(key))]
})
.coerceTo('object')
})
Which produces:
{
"1": [10, 19, 100],
"2": [15, 100, 150]
}

Answer 2

You can call values on an object to get an array of values from it: https://www.rethinkdb.com/api/javascript/#values
If not all of the indexes are present as keys, you could write something like r.range(obj.keys().max()).map(function(i) { return obj(i.coerceTo('string')).default(nil); }).

Answer 3

If the data fields could be any string, something like this could work:
r.db('test')
.table('test')
.getAll(1, {index: 'record'})
.getField('data')
.concatMap(r.row.coerceTo('array'))
.group(r.row(0))
.concatMap([r.row(1)])
.ungroup()
Otherwise, mlucy's suggestion might be used to make it more efficient.
EDIT: on further experimentation, I could not get obj.keys() to be faster than group.