Distinct Query with Cloudant Connector using Loopback in API Connect/StrongLoop - ibm-cloud

Question

I am trying to get distinct values for a query using Loopback with a Cloudant Connector, but I haven't found anything about this in the documentation.
e.g. I need a query to turn this:
[
{
rating: "★★★★★"
},
{
rating: "★★★★★"
},
{
rating: "★★★★★"
},
{
rating: "★★★★★"
},
{
rating: "★★★☆☆"
},
{
rating: "★★★☆☆"
}
]
into this:
[
{
rating: "★★★★★"
},
{
rating: "★★★☆☆"
}
]
I'm using the REST API to query my Products model (above is a filtered view of just the rating field). If there is some sort of filter that I can use without modifying the server that I somehow just missed in the documentation, that would be the best choice.
Is there any way I can add a distinct field like:
/Products?filter[fields][rating]=true?distinct=true
or how can I go about solving this?
Also, I've seen another answer talking about adding a remote method to solve this (something like this for mySQL):
Locations.regions = function (cb) {
var ds = Locations.app.datasources.myDS;
var sql = "SELECT DISTINCT region FROM Locations ORDER BY region"; // here you write your sql query.
ds.connector.execute(sql, [], function (err, regions) {
if (err) {
cb(err, null);
} else {
cb(null, regions);
}
});
};
Locations.remoteMethod(
'regions', {
http: {
path: '/regions',
verb: 'get'
},
returns: {
root: true,
type: 'object'
}
}
);
If this would work, how would I implement it with the Cloudant NoSQL DB connector?
Thanks!

Answer 1

If your documents looked like this:
{
"name": "Star Wars",
"year": 1978,
"rating": "*****"
}
You can create a MapReduce view, which emits doc.rating as the key and uses the build-in _count reducer:
function(doc) {
emit(doc.rating,null);
}
When you query this view with group=true, distinct values of rating will be presented with counts of their occurrence in the data set.