Fetch multiple documents in a stored procedure (Azure DocumentDB) - node.js

Question

I have two document types, Listing and Products. A Listing object contains a list of Products for certain countries, like this:
Listing:
{
"Name": "Default",
"Countries": {
"_default": [
"4QlxAPFcCAAPAAAAAAAAAA==",
"4QlxAPFcCAAHAAAAAAAAAA=="
],
"US": [
"4QlxAPFcCAAIAAAAAAAAAA==",
"4QlxAPFcCAAHAAAAAAAAAA=="
]
},
"Type": "Listing",
"id": "dfed1839-07c5-482b-81c5-669b1dbcd0b6",
"_rid": "4QlxAPFcCAAEAAAAAAAAAA=="
}
Product:
{
"Name": "Widget",
"Price": 3.45,
"Type": "Product",
"_rid": "4QlxAPFcCAAHAAAAAAAAAA=="
}
My goal was to create a stored procedure in the Azure DocumentDB collection taking two parameters, ridand country, which would essentially fetch the Listing document, and the documents for that country, in the most efficient manner possible. My presumption is that loading a Document by its resource Id using getContext().getCollection().readDocument(...) would be the fastest way, thus attempting to create a stored procedure for this.
My attempts have been to nest the consecutive calls (callback hell?), using generator/iterators with yield and then with a pure Promise approach. All of the attempts have given the same result:
It will fetch the first document, but will end quite abruptly after the document has been received.
For reference, here's my latest attempt:
function test(rid, country) {
var collection = getContext().getCollection();
var collectionSelfLink = collection.getSelfLink();
var docsLink = collectionSelfLink + "docs/";
var body = getContext().getResponse().setBody;
function getDocument(rid) {
return new Promise(function(resolve, reject) {
var accepted = collection.readDocument(docsLink + rid, (err, doc, opts) => {
resolve(doc);
});
if (!accepted)
reject("Not accepted");
});
}
getDocument(rid)
.then(doc => {
body("0. First step"); // set test body
// Countries is a Dictionary<string, string[]> with resource ids
return doc.Countries[country] || doc.Countries["_default"];
})
// This is how far it gets, resulting in response "1. Documents to fetch: 2"
.then(a => body("1. Documents to fetch: " + a.length))
.then(a => a.map(function(productId) { return getDoument(productId); }))
.then(a => body("2. It should come this far, right?"))
.then(a => Promise.all(a))
.then(a => body(a))
.catch(function(e) { throw new Error(JSON.stringify(e)); });
}

Answer 1

It turns out that nesting the calls do in fact work, if you alter the response body frequently(?)
The following procedure worked as expected:
function test(rid, country) {
var collection = getContext().getCollection();
var collectionSelfLink = collection.getSelfLink();
var docsLink = collectionSelfLink + "docs/";
var body = getContext().getResponse().setBody;
var accepted = collection.readDocument(docsLink + rid, (err, doc, opts) => {
if (err) throw new Error(err.message);
// Countries is a Dictionary<string, string[]> with resource ids
var offerIds = doc.Countries[country] || doc.Countries["_default"];
var result = [];
for (var docId of offerIds) {
var subAccepted =
collection.readDocument(docsLink + docId, (err, doc, opts) => {
if (err) throw new Error(err.message);
result.push(doc);
});
if (!subAccepted)
throw new Error("A subsequent request was not accepted");
body(result); // <-- Note, setting body in each iteration.
}
});
if (!accepted)
throw new Error("The request was not accepted");
}