Angular Firestore集合查询和排序依据

Question

I am performign a simple query and then want to order by date.

This works perfectly fine:

this.afs.collection('orders', ref=> ref.where('orderStatus', '<', 7));

This throws an error when I want to filter orderStaus < 7 and then order it by date.

this.afs.collection('orders', ref=> ref.where('orderStatus', '<', 7).orderBy('date', 'desc'));

Here is my error:

You have a where filter with an inequality (<, <=, >, or >=) on field 'orderStatus' and so you must also use 'orderStatus' as your first Query.orderBy(), but your first Query.orderBy() is on field 'date' instead.

How can I achieve getting all ordersStatus < 7 AND then sort the orders by date?

Answer 1

Cloud Firestore requires you to first order by the field on which you are applying the range filter on and then order by any other field of your choice.

Reference : https://firebase.google.com/docs/firestore/query-data/order-limit-data

You can achieve this by creating a compound index of range filter field and the field you want to order next for the collection you are querying.

So in your case you need to create a compound index for the orders collection with orderStatus DESC and date DESC .

Reference : https://firebase.google.com/docs/firestore/query-data/indexing

Hope this is useful.