[英]How to retrieve data from Firebase Realtime Database to mySqlite?
上圖顯示了我的 Firebase 數據庫的數據庫結構,這就是我的 firebase 實時數據庫如何節省費用。 如何借助下面給出的數據模型從 firebase 獲取該數據並將其存儲在我的 android 應用程序的 SQlite 數據庫中?
public class Expense {
public String id;
public String amount;
public String description;
public Expense() {}
// [START post_to_map]
@Exclude
public Map < String, Object > toMap() {
HashMap < String, Object > result = new HashMap < > ();
result.put("id", id);
result.put("amount", amount);
result.put("description", description);
return result;
}
// [END post_to_map]
public Expense(String id, String amount, String description) {
this.id = id;
this.amount = amount;
this.description = description;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getAmount() {
return amount;
}
public void setAmount(String amount) {
this.amount = amount;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
}
這是我用來將數據添加到 SQLITE 數據庫的 function
public boolean addExpense(Expense expense) {
ContentValues contentValues = new ContentValues();
contentValues.put("expense_id", expense.getId());
contentValues.put("expense_amount", expense.getAmount());
contentValues.put("expense_description", expense.getDescription());
SQLiteDatabase db = getWritableDatabase();
db.insert(DBHelper.expenses_table, null, contentValues);
return true;
}
如何將實時數據庫中的數據保存到 SQLite 數據庫?
你可能會看看這個answer.It's Related save List to sqlite
要么
要將數據從 firebase 實時數據庫保存到 sql 數據庫,您應該將 ValueEventListener 添加到您存儲費用數據的 DatabaseReference 並循環遍歷每個費用數據並將其傳輸到 addExpense() function。
檢查此示例
您的費用數據模型:
public class Expense {
public String id;
public String amount;
public String description;
public Expense() {
}
// [START post_to_map]
@Exclude
public Map<String, Object> toMap() {
HashMap<String, Object> result = new HashMap<>();
result.put("id", id);
result.put("amount", amount);
result.put("description", description);
return result;
}
// [END post_to_map]
public Expense(String id, String amount, String description) {
this.id = id;
this.amount = amount;
this.description = description;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getAmount() {
return amount;
}
public void setAmount(String amount) {
this.amount = amount;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
}
在這里,您試圖從 firebase 中收集費用清單,那么您可能需要使用此方法:
final FirebaseDatabase database = FirebaseDatabase.getInstance();
DatabaseReference ref = database.getReference("path_to_your_expenses_reference");
ref.addListenerForSingleValueEvent(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
for (DataSnapshot expensedata: dataSnapshot.getChildren()) {
Expense expense = expensedata.getValue(Expense.class);
addExpense(expense);
}
}
@Override
public void onCancelled(DatabaseError databaseError) {
System.out.println("The read failed: " + databaseError.getCode());
}
});
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