Sequelize: on a subset of model A, sum an integer-attribute of an associated model B - sql

Question

I want to do this:
select sum("quantity") as "sum"
from "orderArticles"
inner join "orders"
on "orderArticles"."orderId"="orders"."id"
and "orderArticles"."discountTagId" = 2
and "orders"."paid" is not null;
which results in on my data base:
sum
-----
151
(1 row)
How can I do it?
My Sequelize solution:
The model definitions:
const order = Conn.define('orders', {
id: {
type: Sequelize.BIGINT,
autoIncrement: true,
primaryKey: true
},
// ...
paid: {
type: Sequelize.DATE,
defaultValue: null
},
// ...
},
// ...
})
const orderArticle = Conn.define('orderArticles',
{
id: {
type: Sequelize.BIGINT,
autoIncrement: true,
primaryKey: true
},
// ...
quantity: {
type: Sequelize.INTEGER,
defaultValue: 1
}
},
{
scopes: {
paidOrders: {
include: [
{ model: order, where: { paid: {$ne: null}} }
]
}
},
// ...
})
Associations:
orderArticle.belongsTo(order)
order.hasMany(orderArticle, {onDelete: 'cascade', hooks: true})
I came up with this after hours of research:
db.models.orderArticles
.scope('paidOrders') // select only orders with paid: {$ne: null}
.sum('quantity', { // sum up all resulting quantities
attributes: ['quantity'], // select only the orderArticles.quantity col
where: {discountTagId: 2}, // where orderArticles.discountTagId = 2
group: ['"order"."id"', '"orderArticles"."quantity"'] // don't know why, but Sequelize told me to
})
.then(sum => sum) // return the sum
leads to this sql:
SELECT "orderArticles"."quantity", sum("quantity") AS "sum",
"order"."id" AS "order.id", "order"."taxRate" AS "order.taxRate",
"order"."shippingCosts" AS "order.shippingCosts", "order"."discount"
AS "order.discount", "order"."paid" AS "order.paid",
"order"."dispatched" AS "order.dispatched", "order"."payday" AS
"order.payday", "order"."billNr" AS "order.billNr",
"order"."createdAt" AS "order.createdAt", "order"."updatedAt" AS
"order.updatedAt", "order"."orderCustomerId" AS
"order.orderCustomerId", "order"."billCustomerId" AS
"order.billCustomerId" FROM "orderArticles" AS "orderArticles" INNER
JOIN "orders" AS "order" ON "orderArticles"."orderId" = "order"."id"
AND "order"."paid" IS NOT NULL WHERE "orderArticles"."discountTagId" =
'4' GROUP BY "order"."id", "orderArticles"."quantity";
which has this result on the same data base: 0 rows
If you know what I got wrong please let me know!
Thank you :)

Answer 1

Found the solution:
in the scopes definition on the orderArticle model:
scopes: {
paidOrders: {
include: [{
model: order,
where: { paid: {$ne: null}},
attributes: [] // don't select additional colums!
}]
}
},
//...
and the algorithm:
db.models.orderArticles
.scope('paidOrders')
.sum('quantity', {
attributes: [], // don't select any further cols
where: {discountTagId: 2}
})
Note: In my case it was sufficient to return the promise. I use GraphQL which resolves the result and sends it to the client.