如何从firestore检索数组映射数据并存储在android studio中的数组中？ [关闭]

Question

我想从 firestore 检索数组映射并将其存储在一个数组中，但它似乎根本不起作用，关于如何解决它的任何想法？谢谢...

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code example

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Firebase database example

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Full database structure

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Error

DocumentReference docRef = db.collection("user").document("65pH8UOnV4Pz8oxogsqsL9eE91L2");
            docRef.get().addOnCompleteListener(new OnCompleteListener<DocumentSnapshot>() {
                @Override
                public void onComplete(@NonNull Task<DocumentSnapshot> task) {
                    if (task.isSuccessful()) {
                        DocumentSnapshot document = task.getResult();
                        if (document.exists()) {
                             String[] array = (String[]) document.getData().get("card");
                                    Log.d(TAG, "DocumentSnapshot data: "+ document.getData().get("card"));
                        } else {
                            Log.d(TAG, "No such document");
                        }
                    } else {
                        Log.d(TAG, "get failed with ", task.getException());
                    }
                }
            });

Answer 1

为了解析结果，您可以制作与 firestore 上具有相同结构的模型 java 类，然后在您的 onComplete 方法中使用它来解析。

//UserResponse.java


 public class UserResponse {

private ArrayList<Card> card;

public ArrayList<Card> getCard() {
    return card;
}

public void setCard(ArrayList<Card> card) {
    this.card = card;
}

public String getBalance() {
    return balance;
}

public void setBalance(String balance) {
    this.balance = balance;
}

public String getEmail() {
    return email;
}

public void setEmail(String email) {
    this.email = email;
}

public String getName() {
    return name;
}

public void setName(String name) {
    this.name = name;
}

public String getPhonenumber() {
    return phonenumber;
}

public void setPhonenumber(String phonenumber) {
    this.phonenumber = phonenumber;
}

private String balance;
private String email;
private String name;
private String phonenumber;


}
//Card.java
public class Card{

    private String cvv;

    private String exp;

    public String getCvv() {
        return cvv;
    }

    public void setCvv(String cvv) {
        this.cvv = cvv;
    }

    public String getExp() {
        return exp;
    }

    public void setExp(String exp) {
        this.exp = exp;
    }

    public String getCarddetail() {
        return carddetail;
    }

    public void setCarddetail(String carddetail) {
        this.carddetail = carddetail;
    }

    private String carddetail;
   
}

然后在firestore中获取代码更改添加以下行

UserResponse userResponse = document.toObject(UserResponse.class)
ArrayList<Card> cards = userResponse.getCard();

像这样：

DocumentReference docRef = db.collection("user").document("65pH8UOnV4Pz8oxogsqsL9eE91L2");
        docRef.get().addOnCompleteListener(new OnCompleteListener<DocumentSnapshot>() {
    @Override
    public void onComplete(@NonNull Task<DocumentSnapshot> task) {
        if (task.isSuccessful()) {
            DocumentSnapshot document = task.getResult();
            if (document.exists()) {
                UserResponse userResponse = document.toObject(UserResponse.class);
             ArrayList<Card> cards = userResponse.getCard();

                Log.d(TAG, "DocumentSnapshot data: "+ userResponse.getCard());
            } else {
                Log.d(TAG, "No such document");
            }
        } else {
            Log.d(TAG, "get failed with ", task.getException());
        }
    }
});