How To Sort Firebase Records By Two Fields (android)
Solution 1:
Unfortunately, Firebase Realtime database does not support queries on multiple properties, supports only queries on a single child property. So, you're correct in guessing that you'll need to create an extra field to keep both fields. So to achieve this, you need to create a new field which in your database should look like this:
Firebase-root
|
--- itemId
|
--- a: valueOfA
|
--- b: valueOfB
|
--- a_b: valueOfA_valueOfB
So as you see, the a_b
property combines the values that you want to filter on.
Unlike Firebase Realtime database, Cloud Firestore allows compound queries. You should take a look at this. So a query as the one below is allowed in Cloud Firestore without creating a combined property.
itemIdRef.whereEqualTo("a", "valueOfA").whereEqualTo("b", "valueOfB");
When you order strings this is the normal ordering method. A quick fix would be to add two zeros before each second element like this: "1516428687_001"
, "1516428687_002"
, "1516428687_012"
. Now your order will be fine. For more explanations, please see my answer from this post.
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