转义房间数据库查询中的特殊字符

Question

我的 Dao 文件中有以下代码。

@Query("SELECT * FROM ${Test.TABLE_NAME} WHERE primary_key = :primaryKey LIMIT 1")
fun selectTest(primaryKey: String): Test?

问题是primaryKey 是一个可以包含/ 的字符串。如Test/4。这会导致查询失败。我尝试在:primaryKey 周围加上引号，但随后 Room 不再绑定它。我还尝试在 primaryKey 字符串中添加转义引号，该字符串将绑定到查询，但这也不起作用。

关于如何处理的想法？

Answer 1

表名包含特殊字符，需要用 SQLite 和 ROOM 都可以接受的字符括起来。

在 SQLITE 中，您可以使用以下之一：-

`tablename` 
"tablename" 
'tablename' 
[tablename] 

但是 ROOM 比较麻烦，因为它不允许您使用中间的两个。因此尝试：-

@Query("SELECT * FROM `${Test.TABLE_NAME}` WHERE primary_key = :primaryKey LIMIT 1")
fun selectTest(primaryKey: String): Test?

或

@Query("SELECT * FROM [${Test.TABLE_NAME}] WHERE primary_key = :primaryKey LIMIT 1")
fun selectTest(primaryKey: String): Test?

测试

• 请注意，以上是原理代码，未经测试或运行，因此可能包含小错误。但是，为了方便起见，已通过改编另一个问题的答案中的代码来测试等效的 java 代码。

使用：-

@Query("SELECT * FROM `/cards` WHERE card_name LIKE :cardName")
Cards[] getCardsByName(String cardName);

@Query("SELECT * FROM [" + GamesDatabase.TABLENAMECARDS +"] WHERE card_name LIKE :cardName")
Cards[] getFunnyCardsByName(String cardName);

• GamesDatabase.TABLENAMECARDS 是相同的表名，但作为 CONSTANT 即 /cards

上面的 Dao 使用了 :-

    String cardToGet = "%/";
    Cards[] retrievedCards = mGamesDao.getCardsByName(cardToGet);
    for (Cards c: retrievedCards) {
        logCardsInfo(c,"GETCARDSBYNAME");
    }

    retrievedCards = mGamesDao.getFunnyCardsByName(cardToGet);
    for (Cards c: retrievedCards) {
        logCardsInfo(c,"GETCARDSBYFUNNYNAME");
    }

logCardsInfo 方法将 Card、名称、值、id、Folder 和 Category 写入日志，TAG 是传递的第二个参数。

其中 Cards 包含一包卡片（带有一个名为 ooops 的额外花色，不是花色等同于类别，文件夹每个类别有两个，但 7 在 normalcards 文件夹中）但卡片的名称值为 7是 7/ 而不是 7，因此两者都将提取 5 张卡片：-

2019-09-16 15:01:46.084 19140-19140/aso.so57943963foreignkeys D/GETCARDSBYNAME: Card Name is 7/
        Value is 7
        CardID is 10
        In Folder NormalCards
            In Category Spades
2019-09-16 15:01:46.089 19140-19140/aso.so57943963foreignkeys D/GETCARDSBYNAME: Card Name is 7/
        Value is 7
        CardID is 23
        In Folder NormalCards
            In Category Hearts
2019-09-16 15:01:46.094 19140-19140/aso.so57943963foreignkeys D/GETCARDSBYNAME: Card Name is 7/
        Value is 7
        CardID is 36
        In Folder NormalCards
            In Category Clubs
2019-09-16 15:01:46.101 19140-19140/aso.so57943963foreignkeys D/GETCARDSBYNAME: Card Name is 7/
        Value is 7
        CardID is 49
        In Folder NormalCards
            In Category Diamonds
2019-09-16 15:01:46.107 19140-19140/aso.so57943963foreignkeys D/GETCARDSBYNAME: Card Name is 7/
        Value is 7
        CardID is 62
        In Folder NormalCards
            In Category ooops
2019-09-16 15:01:46.110 19140-19140/aso.so57943963foreignkeys D/GETCARDSBYFUNNYNAME: Card Name is 7/
        Value is 7
        CardID is 10
        In Folder NormalCards
            In Category Spades
2019-09-16 15:01:46.114 19140-19140/aso.so57943963foreignkeys D/GETCARDSBYFUNNYNAME: Card Name is 7/
        Value is 7
        CardID is 23
        In Folder NormalCards
            In Category Hearts
2019-09-16 15:01:46.118 19140-19140/aso.so57943963foreignkeys D/GETCARDSBYFUNNYNAME: Card Name is 7/
        Value is 7
        CardID is 36
        In Folder NormalCards
            In Category Clubs
2019-09-16 15:01:46.121 19140-19140/aso.so57943963foreignkeys D/GETCARDSBYFUNNYNAME: Card Name is 7/
        Value is 7
        CardID is 49
        In Folder NormalCards
            In Category Diamonds
2019-09-16 15:01:46.122 19140-19140/aso.so57943963foreignkeys D/GETCARDSBYFUNNYNAME: Card Name is 7/
        Value is 7
        CardID is 62
        In Folder NormalCards
            In Category ooops