如何从cloud-firestore数据库中搜索？

Question

我希望用户输入他们的电子邮件和密码。身份验证后，根据他们的电子邮件，我想检查他们是否是管理员，然后打开不同的活动。我该如何执行搜索查询？它甚至可能吗？

以下是对我有用的答案。一般情况下见亚历克斯回答。

mAuth.signInWithEmailAndPassword(email,password).addOnCompleteListener(new OnCompleteListener<AuthResult>() {
            @Override
            public void onComplete(@NonNull Task<AuthResult> task) {
                if (task.isSuccessful()) {
                    rootRef.collection("Users").whereEqualTo("Email","ashish@gmail.com").get().addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
                        @Override
                        public void onComplete(@NonNull Task<QuerySnapshot> task) {
                            if (task.isSuccessful()) {
                                for (DocumentSnapshot document : task.getResult()) {
                                    if (document.getString("Admin").equals("Yes")) {
                                        Toast.makeText(Login.this, "Logged In!", Toast.LENGTH_LONG).show();
                                        finish();
                                        startActivity(new Intent(Login.this, MainActivity.class));
                                    } else {
                                        Toast.makeText(Login.this, "Logged In!", Toast.LENGTH_LONG).show();
                                        finish();
                                        startActivity(new Intent(Login.this, nonadmin.class));
                                    }
                                }
                            } else {
                                mProgressBar.setVisibility(View.GONE);
                                Toast.makeText(Login.this, "Sign In Problem", Toast.LENGTH_LONG).show();
                            }
                        }
                    });

                }
            }
        });

Answer 1

要解决此问题，请使用以下代码：

FirebaseFirestore rootRef = FirebaseFirestore.getInstance();
rootRef.collection("Users").whereEqualTo("Email", "ashish@startup.com").get().addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
    @Override
    public void onComplete(@NonNull Task<QuerySnapshot> task) {
        if (task.isSuccessful()) {
            for (DocumentSnapshot document : task.getResult()) {
                if (document.getString("Admin").equals("Yes")) {
                    Log.d(TAG, "User is Admin!");
                }
            }
        } else {
            Log.d(TAG, "Error getting documents: ", task.getException());
        }
    }
});

输出结果为：User is Admin!。

不要忘记设置这样的安全规则：

service cloud.firestore {
  match /databases/{database}/documents {
    match /{document=**} {
      allow read, write;
    }
  }
}