How to add more than one firebase sort-CodePudding

I want to do double filtering related to Firestore. I have a city selection button and the second one is a ListView that selects the products category.

My category filtering works well, but I don't know how to add more city filtering for it.

](https://i.stack.imgur.com/68SIS.png)

I tried to write something like this

stocks.where('city', arrayContains: 'Chicago').where('tags', arrayContains: 'All');

But this is wrong. I will be grateful for any answer.

CodePudding user response：

The following line of code:

stocks.where('city', arrayContains: 'Chicago').where('tags', arrayContains: 'All');

Will not work, because there is a query limitation that says:

You can use at most one array-contains clause per query. You can't combine array-contains with array-contains-any.

So you can use only one arrayContains in a query.

To solve this, you should consider using maps, and not arrays, a case in which the following database schema will do the trick:

Firestore-root
   |
   --- stocks
         |
         --- $stockId
                |
                --- cities
                |    |
                |    --- "Chicago": true
                |
                --- tags
                     |
                     --- "All": true

Then a query like the one below will work perfectly fine:

stocks.whereEqualTo("cities.Chicago", true).whereEqualTo("tags.All", true);