FaunaDB get entries by date range with index binding not working - faunadb

Question

I am struggling to get an Index by Date to work with a Range.
I have this collection called orders:
CreateCollection({name: "orders"})
And I have these sample entries, with one attribute called mydate. As you see it is just a string. And I do need to create the date as a string since in my DB we already have around 12K records with dates like that so I cant just start using the Date() to create them.
Create(Collection("orders"), {data: {"mydate": "2020-07-10"}})
Create(Collection("orders"), {data: {"mydate": "2020-07-11"}})
Create(Collection("orders"), {data: {"mydate": "2020-07-12"}})
I have created this index that computes the date to and actual Date object
CreateIndex({
name: "orders_by_my_date",
source: [
{
collection: Collection("orders"),
fields: {
date: Query(Lambda("order", Date(Select(["data", "mydate"], Var("order"))))),
},
},
],
terms: [
{
binding: "date",
},
],
});
If I try to fetch a single date the index works.
// this works
Paginate(
Match(Index("orders_by_my_date"), Date("2020-07-10"))
);
// ---
{
data: [Ref(Collection("orders"), "278496072502870530")]
}
But when I try to get a Range it never finds data.
// This does NOT work :(
Paginate(
Range(Match(Index("orders_by_my_date")), Date("2020-07-09"), Date("2020-07-15"))
);
// ---
{
data: []
}
Why the index does not work with a Range?

Answer 1

Range operates on the values of an index, not on the terms.
See: https://docs.fauna.com/fauna/current/api/fql/functions/range?lang=javascript
You need to change your index definition to:
CreateIndex({
name: "orders_by_my_date",
source: [
{
collection: Collection("orders"),
fields: {
date: Query(Lambda("order", Date(Select(["data", "mydate"], Var("order"))))),
},
},
],
values: [
{ binding: "date" },
{ field: ["ref"] },
],
})
Then you can get the results that you expect:
> Paginate(Range(Match(Index('orders')), Date('2020-07-11'), Date('2020-07-15')))
{
data: [
[
Date("2020-07-11"),
Ref(Collection("orders"), "278586211497411072")
],
[
Date("2020-07-12"),
Ref(Collection("orders"), "278586213229658624")
],
[
Date("2020-07-13"),
Ref(Collection("orders"), "278586215000703488")
],
[
Date("2020-07-14"),
Ref(Collection("orders"), "278586216887091712")
],
[
Date("2020-07-15"),
Ref(Collection("orders"), "278586218585784832")
]
]
}

Answer 2

Another alternative is to use a filter with a lambda expression to validate which values you want
Filter(
Paginate(Documents(Collection('orders'))),
Lambda('order',
And(
GTE(Select(['data', 'mydate'], Var('order')), '2020-07-09'),
LTE(Select(['data', 'mydate'], Var('order')), '2020-07-15')
)
)
)
You can update the conditions as you need
I believe this will work with the strings you have already

Answer 3

There are some mistakes here, first of all, you have to create documents that way:
Create(Collection("orders"), {data: {"mydate": ToDate("2020-07-10")}})
The index has to be created like this:
CreateIndex(
{
name: "orders_by_my_date",
source: Collection("orders"),
values:[{field:['data','mydate']},{field:['ref']}]
}
)
and finally, you can query your index and range:
Paginate(Range(Match('orders_by_my_date'),[Date("2020-07-09")], [Date("2020-07-15")]))
{ data:
[ [ Date("2020-07-10"),
Ref(Collection("orders"), "278532030954734085") ],
[ Date("2020-07-11"),
Ref(Collection("orders"), "278532033804763655") ],
[ Date("2020-07-12"),
Ref(Collection("orders"), "278532036737630725") ] ] }
or if you want to get the full doc:
Map(Paginate(Range(Match('orders_by_my_date'),[Date("2020-07-09")], [Date("2020-07-15")])),Lambda(['date','ref'],Get(Var('ref'))))
{ data:
[ { ref: Ref(Collection("orders"), "278532030954734085"),
ts: 1601887694290000,
data: { mydate: Date("2020-07-10") } },
{ ref: Ref(Collection("orders"), "278532033804763655"),
ts: 1601887697015000,
data: { mydate: Date("2020-07-11") } },
{ ref: Ref(Collection("orders"), "278532036737630725"),
ts: 1601887699800000,
data: { mydate: Date("2020-07-12") } } ] }