如何检查该字段在Firestore中是否存在? [英] How to check if the field exists in firestore?

问题描述

我正在检查称为 attending 的布尔字段是否存在，但是我不确定如何做到这一点.

I am checking whether the Boolean field called attending exists, however I am not sure how to do that.

是否有诸如 .child().exists()之类的功能或我可以使用的类似功能?

Is there a function such as .child().exists() or something similar that I could use?

firebaseFirestore.collection("Events")
    .document(ID)
    .collection("Users")
    .get()
    .addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
        @Override
        public void onComplete(@NonNull Task<QuerySnapshot> task) {
            if(task.isSuccessful()) {
                for(QueryDocumentSnapshot document: task.getResult()){
                    attending = document.getBoolean("attending");
                }
            }
        }
    });

推荐答案

您现在正在做的是正确的-您必须阅读文档并检查快照以查看该字段是否存在.没有比这更短的方法了.

What you're doing now is correct - you have to read the document and examine the snapshot to see if the field exists. There is no shorter way to do this.

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