Updating array elements that matches a specific criteria - rethinkdb

Question

Let's say I have the following array
var data = [{ id: 0, points: 1 }, { id: 1, points: 2 }]
I would like to update my table which contains
{
"doc-1": {
"id": "abcxyz123",
"entries": [
{ "id": 0, "points": 5 },
{ "id": 1, "points": 3 },
{ "id": 2, "points": 0 }
]
}
}
so that I add the points-field in the data array to the points-field for each element in the "entries" array in "doc-1" that matches the corresponding id in the data array. The end result would look like:
{
"doc-1": {
"id": "abcxyz123",
"entries": [
{ "id": 0, "points": 6 },
{ "id": 1, "points": 4 },
{ "id": 2, "points": 0 }
]
}
}
How do I go about to write such a query in ReQL?

Answer 1

I assume that the actual document in the table looks like this for now:
{
"id": "abcxyz123",
"entries": [{
"id": 0,
"points": 5
}, {
"id": 1,
"points": 3
}, {
"id": 2,
"points": 0
}]
}
That is without the doc-1 nesting.
Then your update can be done like this:
r.table('t1').update(
{
entries: r.row('entries').map(function(e) {
return r.do(r.expr(data)('id').indexesOf(e('id')), function(dataIndexes) {
return r.branch(
dataIndexes.isEmpty(),
e,
{
id: e('id'),
points: e('points').add(r.expr(data)(dataIndexes(0))('points'))
});
});
})
})
I'm using map to map over each entry in entries, and indexesOf to find the corresponding entry in data if it exists.
Note that this doesn't add new entries to the entries list, but only updates existing ones. Please let me know if you need to add new entries as well.
If your documents actually have the doc-1 field first, this query should do the job:
r.table('t1').update(
{ 'doc-1':
{
entries: r.row('doc-1')('entries').map(function(e) {
return r.do(r.expr(data)('id').indexesOf(e('id')), function(dataIndexes) {
return r.branch(
dataIndexes.isEmpty(),
e,
{
id: e('id'),
points: e('points').add(r.expr(data)(dataIndexes(0))('points'))
});
});
})
}
})