为什么.whereEqualTo不起作用？

Question

为什么这样工作

Query firstQuery1 = firebaseFirestore.collection("Test").whereEqualTo("test", "1");

这不起作用

Query firstQuery1 = firebaseFirestore.collection("Test");
firstQuery1.whereEqualTo("test", "1");

Answer 1

firestore.collection("Test")返回CollectionReference类型的对象，而ref.whereEqualTo(..)返回Query

所以而不是

Query firstQuery1 = firestore.collection("Test");
firstQuery1.whereEqualTo("test", "1");

它需要

CollectionReference ref = firestore.collection("Test");
Query query = ref.whereEqualTo("test","1");