房间数据库迁移：java.lang.IllegalStateException：迁移没有正确处理 <table_name>
Room Database Migration: java.lang.IllegalStateException: Migration didn't properly handle <table_name>
我正在尝试使用房间数据库创建一个新的 table。我遵循了我在我的程序中已经拥有的第一个 table 中使用的相同原则，但是当时间到了 运行 应用程序时，我得到了这个错误：
Caused by: java.lang.IllegalStateException: Migration didn't properly handle: WaterFountainEntry(com.mpms.relatorioacessibilidadecortec.entities.WaterFountainEntry).
Expected:
TableInfo{name='WaterFountainEntry', columns={waterFountainHeight=Column{name='waterFountainHeight', type='REAL', affinity='4', notNull=false, primaryKeyPosition=0, defaultValue='null'}, waterFountainID=Column{name='waterFountainID', type='INTEGER', affinity='3', notNull=false, primaryKeyPosition=1, defaultValue='null'}, cupHolderHeight=Column{name='cupHolderHeight', type='REAL', affinity='4', notNull=false, primaryKeyPosition=0, defaultValue='null'}, schoolEntryID=Column{name='schoolEntryID', type='INTEGER', affinity='3', notNull=false, primaryKeyPosition=0, defaultValue='null'}, waterFountApproximation=Column{name='waterFountApproximation', type='REAL', affinity='4', notNull=false, primaryKeyPosition=0, defaultValue='null'}}, foreignKeys=[ForeignKey{referenceTable='SchoolEntry', onDelete='CASCADE', onUpdate='CASCADE', columnNames=[schoolEntryID], referenceColumnNames=[cadID]}], indices=[]}
Found:
TableInfo{name='WaterFountainEntry', columns={waterFountainID=Column{name='waterFountainID', type='INTEGER', affinity='3', notNull=true, primaryKeyPosition=1, defaultValue='null'}, waterFountainHeight=Column{name='waterFountainHeight', type='DOUBLE', affinity='4', notNull=true, primaryKeyPosition=0, defaultValue='null'}, cupHolderHeight=Column{name='cupHolderHeight', type='DOUBLE', affinity='4', notNull=true, primaryKeyPosition=0, defaultValue='null'}, schoolEntryID=Column{name='schoolEntryID', type='INTEGER', affinity='3', notNull=true, primaryKeyPosition=0, defaultValue='null'}, waterFountApproximation=Column{name='waterFountApproximation', type='DOUBLE', affinity='4', notNull=true, primaryKeyPosition=0, defaultValue='null'}}, foreignKeys=[ForeignKey{referenceTable='SchoolEntry', onDelete='NO ACTION', onUpdate='NO ACTION', columnNames=[schoolEntryID], referenceColumnNames=[cadID]}], indices=[]}
通过阅读此错误消息，我确实收集到该程序需要与某些字段不同的类型（并且可能也与它们不同的顺序），但事实是它不应该那样。我确保按照我在实体中放置字段的方式编写迁移 class，如下所示：
<Migration Class and Database Creation>
static final Migration MIGRATION_2_3 = new Migration(2,3) {
@Override
public void migrate(@NonNull SupportSQLiteDatabase database) {
database.execSQL("CREATE TABLE WaterFountainEntry (waterFountainID INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL," +
"schoolEntryID INTEGER NOT NULL, waterFountainHeight DOUBLE NOT NULL, cupHolderHeight DOUBLE NOT NULL," +
"waterFountApproximation DOUBLE NOT NULL, FOREIGN KEY (schoolEntryID) REFERENCES SchoolEntry (cadID))");
}
};
public static ReportDatabase getDatabase(final Context context) {
if (INSTANCE == null){
synchronized (ReportDatabase.class) {
if (INSTANCE == null) {
INSTANCE = Room.databaseBuilder(context.getApplicationContext(), ReportDatabase.class, "ReportDatabase")
.addCallback(roomCallback).addMigrations(MIGRATION_2_3).build();
}
}
}
return INSTANCE;
}
<WaterFountainEntry entity>
@Entity(foreignKeys = @ForeignKey(entity = SchoolEntry.class, parentColumns = "cadID", childColumns = "schoolEntryID",
onDelete = CASCADE, onUpdate = CASCADE))
public class WaterFountainEntry {
@PrimaryKey(autoGenerate = true)
@NonNull
private Integer waterFountainID;
@NonNull
private Integer schoolEntryID;
@NonNull
private Double waterFountainHeight;
@NonNull
private Double cupHolderHeight;
@NonNull
private Double waterFountApproximation;
/** getters & setters **/
public WaterFountainEntry(@NonNull Integer schoolEntryID, @NonNull Double waterFountainHeight,
@NonNull Double cupHolderHeight, @NonNull Double waterFountApproximation) {
this.schoolEntryID = schoolEntryID;
this.waterFountainHeight = waterFountainHeight;
this.cupHolderHeight = cupHolderHeight;
this.waterFountApproximation = waterFountApproximation;
}
那么，可能是什么错误？确实看了很多文档也没找到这个问题的原因
绿色列是您的迁移应该看起来的样子。
请检查突出显示的字段并进行类似于绿色的更改，因为这是您的预期结果。
下面是link到diff checker的对比
只需比较找到的结果和预期的结果，您就会知道在迁移中需要做哪些更改
Expected:
TableInfo{name='WaterFountainEntry', columns={waterFountainHeight=Column{name='waterFountainHeight', type='REAL', affinity='4', notNull=false, primaryKeyPosition=0, defaultValue='null'}, waterFountainID=Column{name='waterFountainID', type='INTEGER', affinity='3', notNull=false, primaryKeyPosition=1, defaultValue='null'}, cupHolderHeight=Column{name='cupHolderHeight', type='REAL', affinity='4', notNull=false, primaryKeyPosition=0, defaultValue='null'}, schoolEntryID=Column{name='schoolEntryID', type='INTEGER', affinity='3', notNull=false, primaryKeyPosition=0, defaultValue='null'}, waterFountApproximation=Column{name='waterFountApproximation', type='REAL', affinity='4', notNull=false, primaryKeyPosition=0, defaultValue='null'}}, foreignKeys=[ForeignKey{referenceTable='SchoolEntry', onDelete='CASCADE', onUpdate='CASCADE', columnNames=[schoolEntryID], referenceColumnNames=[cadID]}], indices=[]}
Found:
TableInfo{name='WaterFountainEntry', columns={waterFountainID=Column{name='waterFountainID', type='INTEGER', affinity='3', notNull=true, primaryKeyPosition=1, defaultValue='null'}, waterFountainHeight=Column{name='waterFountainHeight', type='DOUBLE', affinity='4', notNull=true, primaryKeyPosition=0, defaultValue='null'}, cupHolderHeight=Column{name='cupHolderHeight', type='DOUBLE', affinity='4', notNull=true, primaryKeyPosition=0, defaultValue='null'}, schoolEntryID=Column{name='schoolEntryID', type='INTEGER', affinity='3', notNull=true, primaryKeyPosition=0, defaultValue='null'}, waterFountApproximation=Column{name='waterFountApproximation', type='DOUBLE', affinity='4', notNull=true, primaryKeyPosition=0, defaultValue='null'}}, foreignKeys=[ForeignKey{referenceTable='SchoolEntry', onDelete='NO ACTION', onUpdate='NO ACTION', columnNames=[schoolEntryID], referenceColumnNames=[cadID]}], indices=[]}
预期的和找到的 SQL 脚本之间存在许多差异；以 cupHolderHeight 列为例：
杯架高度列：
- 预期：
REAL 发现：DOUBLE --> 将其更改为 REAL（基本上
SQLite) 中没有 DOUBLE 类型
- 预期
notNull=false，发现 notNull=true --> 将其更改为 false（即 NULL）
将其应用于您的迁移 SQL 脚本：
将cupHolderHeight DOUBLE NOT NULL改为cupHolderHeight REAL
您需要浏览其他栏目并执行相同的操作。最终脚本应该是这样的：
database.execSQL("CREATE TABLE WaterFountainEntry (waterFountainID INTEGER PRIMARY KEY AUTOINCREMENT," +
"schoolEntryID INTEGER, waterFountainHeight REAL, cupHolderHeight REAL," +
"waterFountApproximation REAL, FOREIGN KEY (schoolEntryID) REFERENCES SchoolEntry (cadID) ON UPDATE CASCADE ON DELETE CASCADE)");
您还可以考虑 以获得更多说明。
用于排列和比较找到的和预期的脚本：
您可以使用编程脚本对它们进行排序，但这里有一种使用一些工具对它们进行排序的方法：
- 将第一个（预期）复制到文本编辑器中：
TableInfo{name='WaterFountainEntry', columns={waterFountainHeight=Column{name='waterFountainHeight', type='REAL', affinity='4', notNull=false, primaryKeyPosition=0, defaultValue='null'}, waterFountainID=Column{name='waterFountainID', type='INTEGER', affinity='3', notNull=false, primaryKeyPosition=1, defaultValue='null'}, cupHolderHeight=Column{name='cupHolderHeight', type='REAL', affinity='4', notNull=false, primaryKeyPosition=0, defaultValue='null'}, schoolEntryID=Column{name='schoolEntryID', type='INTEGER', affinity='3', notNull=false, primaryKeyPosition=0, defaultValue='null'}, waterFountApproximation=Column{name='waterFountApproximation', type='REAL', affinity='4', notNull=false, primaryKeyPosition=0, defaultValue='null'}}, foreignKeys=[ForeignKey{referenceTable='SchoolEntry', onDelete='CASCADE', onUpdate='CASCADE', columnNames=[schoolEntryID], referenceColumnNames=[cadID]}], indices=[]}
- 用
},\n替换}, --> 你必须知道如何在文本编辑器中添加换行符：
TableInfo{name='WaterFountainEntry', columns={waterFountainHeight=Column{name='waterFountainHeight', type='REAL', affinity='4', notNull=false, primaryKeyPosition=0, defaultValue='null'},
waterFountainID=Column{name='waterFountainID', type='INTEGER', affinity='3', notNull=false, primaryKeyPosition=1, defaultValue='null'},
cupHolderHeight=Column{name='cupHolderHeight', type='REAL', affinity='4', notNull=false, primaryKeyPosition=0, defaultValue='null'},
schoolEntryID=Column{name='schoolEntryID', type='INTEGER', affinity='3', notNull=false, primaryKeyPosition=0, defaultValue='null'},
waterFountApproximation=Column{name='waterFountApproximation', type='REAL', affinity='4', notNull=false, primaryKeyPosition=0, defaultValue='null'}},
foreignKeys=[ForeignKey{referenceTable='SchoolEntry', onDelete='CASCADE', onUpdate='CASCADE', columnNames=[schoolEntryID], referenceColumnNames=[cadID]}], indices=[]}
现在每一列都在单独的行中：
- 对另一个（已找到）执行 1 和 2：
TableInfo{name='WaterFountainEntry', columns={waterFountainID=Column{name='waterFountainID', type='INTEGER', affinity='3', notNull=true, primaryKeyPosition=1, defaultValue='null'},
waterFountainHeight=Column{name='waterFountainHeight', type='DOUBLE', affinity='4', notNull=true, primaryKeyPosition=0, defaultValue='null'},
cupHolderHeight=Column{name='cupHolderHeight', type='DOUBLE', affinity='4', notNull=true, primaryKeyPosition=0, defaultValue='null'},
schoolEntryID=Column{name='schoolEntryID', type='INTEGER', affinity='3', notNull=true, primaryKeyPosition=0, defaultValue='null'},
waterFountApproximation=Column{name='waterFountApproximation', type='DOUBLE', affinity='4', notNull=true, primaryKeyPosition=0, defaultValue='null'}},
foreignKeys=[ForeignKey{referenceTable='SchoolEntry', onDelete='NO ACTION', onUpdate='NO ACTION', columnNames=[schoolEntryID], referenceColumnNames=[cadID]}], indices=[]}
- 现在很容易按字母顺序对它们进行排序并将一个值与另一个值进行比较，（Excel 可以作为一种工具）。
获得正确 SQL 的简单技巧是让 Room 为您生成 SQL。
创建实体，然后编译 (Cntrl+F9) 然后查看生成的 java（从 Android 视图），然后查找与@Databaseclass后缀为_Impl，然后找到createAllTables方法，SQL就在那里。这正是 Room 所期望的。
例如:-
我正在尝试使用房间数据库创建一个新的 table。我遵循了我在我的程序中已经拥有的第一个 table 中使用的相同原则，但是当时间到了 运行 应用程序时，我得到了这个错误：
Caused by: java.lang.IllegalStateException: Migration didn't properly handle: WaterFountainEntry(com.mpms.relatorioacessibilidadecortec.entities.WaterFountainEntry).
Expected:
TableInfo{name='WaterFountainEntry', columns={waterFountainHeight=Column{name='waterFountainHeight', type='REAL', affinity='4', notNull=false, primaryKeyPosition=0, defaultValue='null'}, waterFountainID=Column{name='waterFountainID', type='INTEGER', affinity='3', notNull=false, primaryKeyPosition=1, defaultValue='null'}, cupHolderHeight=Column{name='cupHolderHeight', type='REAL', affinity='4', notNull=false, primaryKeyPosition=0, defaultValue='null'}, schoolEntryID=Column{name='schoolEntryID', type='INTEGER', affinity='3', notNull=false, primaryKeyPosition=0, defaultValue='null'}, waterFountApproximation=Column{name='waterFountApproximation', type='REAL', affinity='4', notNull=false, primaryKeyPosition=0, defaultValue='null'}}, foreignKeys=[ForeignKey{referenceTable='SchoolEntry', onDelete='CASCADE', onUpdate='CASCADE', columnNames=[schoolEntryID], referenceColumnNames=[cadID]}], indices=[]}
Found:
TableInfo{name='WaterFountainEntry', columns={waterFountainID=Column{name='waterFountainID', type='INTEGER', affinity='3', notNull=true, primaryKeyPosition=1, defaultValue='null'}, waterFountainHeight=Column{name='waterFountainHeight', type='DOUBLE', affinity='4', notNull=true, primaryKeyPosition=0, defaultValue='null'}, cupHolderHeight=Column{name='cupHolderHeight', type='DOUBLE', affinity='4', notNull=true, primaryKeyPosition=0, defaultValue='null'}, schoolEntryID=Column{name='schoolEntryID', type='INTEGER', affinity='3', notNull=true, primaryKeyPosition=0, defaultValue='null'}, waterFountApproximation=Column{name='waterFountApproximation', type='DOUBLE', affinity='4', notNull=true, primaryKeyPosition=0, defaultValue='null'}}, foreignKeys=[ForeignKey{referenceTable='SchoolEntry', onDelete='NO ACTION', onUpdate='NO ACTION', columnNames=[schoolEntryID], referenceColumnNames=[cadID]}], indices=[]}
通过阅读此错误消息，我确实收集到该程序需要与某些字段不同的类型（并且可能也与它们不同的顺序），但事实是它不应该那样。我确保按照我在实体中放置字段的方式编写迁移 class，如下所示：
<Migration Class and Database Creation>
static final Migration MIGRATION_2_3 = new Migration(2,3) {
@Override
public void migrate(@NonNull SupportSQLiteDatabase database) {
database.execSQL("CREATE TABLE WaterFountainEntry (waterFountainID INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL," +
"schoolEntryID INTEGER NOT NULL, waterFountainHeight DOUBLE NOT NULL, cupHolderHeight DOUBLE NOT NULL," +
"waterFountApproximation DOUBLE NOT NULL, FOREIGN KEY (schoolEntryID) REFERENCES SchoolEntry (cadID))");
}
};
public static ReportDatabase getDatabase(final Context context) {
if (INSTANCE == null){
synchronized (ReportDatabase.class) {
if (INSTANCE == null) {
INSTANCE = Room.databaseBuilder(context.getApplicationContext(), ReportDatabase.class, "ReportDatabase")
.addCallback(roomCallback).addMigrations(MIGRATION_2_3).build();
}
}
}
return INSTANCE;
}
<WaterFountainEntry entity>
@Entity(foreignKeys = @ForeignKey(entity = SchoolEntry.class, parentColumns = "cadID", childColumns = "schoolEntryID",
onDelete = CASCADE, onUpdate = CASCADE))
public class WaterFountainEntry {
@PrimaryKey(autoGenerate = true)
@NonNull
private Integer waterFountainID;
@NonNull
private Integer schoolEntryID;
@NonNull
private Double waterFountainHeight;
@NonNull
private Double cupHolderHeight;
@NonNull
private Double waterFountApproximation;
/** getters & setters **/
public WaterFountainEntry(@NonNull Integer schoolEntryID, @NonNull Double waterFountainHeight,
@NonNull Double cupHolderHeight, @NonNull Double waterFountApproximation) {
this.schoolEntryID = schoolEntryID;
this.waterFountainHeight = waterFountainHeight;
this.cupHolderHeight = cupHolderHeight;
this.waterFountApproximation = waterFountApproximation;
}
那么，可能是什么错误？确实看了很多文档也没找到这个问题的原因
绿色列是您的迁移应该看起来的样子。
请检查突出显示的字段并进行类似于绿色的更改，因为这是您的预期结果。
下面是link到diff checker的对比
只需比较找到的结果和预期的结果，您就会知道在迁移中需要做哪些更改
Expected:
TableInfo{name='WaterFountainEntry', columns={waterFountainHeight=Column{name='waterFountainHeight', type='REAL', affinity='4', notNull=false, primaryKeyPosition=0, defaultValue='null'}, waterFountainID=Column{name='waterFountainID', type='INTEGER', affinity='3', notNull=false, primaryKeyPosition=1, defaultValue='null'}, cupHolderHeight=Column{name='cupHolderHeight', type='REAL', affinity='4', notNull=false, primaryKeyPosition=0, defaultValue='null'}, schoolEntryID=Column{name='schoolEntryID', type='INTEGER', affinity='3', notNull=false, primaryKeyPosition=0, defaultValue='null'}, waterFountApproximation=Column{name='waterFountApproximation', type='REAL', affinity='4', notNull=false, primaryKeyPosition=0, defaultValue='null'}}, foreignKeys=[ForeignKey{referenceTable='SchoolEntry', onDelete='CASCADE', onUpdate='CASCADE', columnNames=[schoolEntryID], referenceColumnNames=[cadID]}], indices=[]}
Found:
TableInfo{name='WaterFountainEntry', columns={waterFountainID=Column{name='waterFountainID', type='INTEGER', affinity='3', notNull=true, primaryKeyPosition=1, defaultValue='null'}, waterFountainHeight=Column{name='waterFountainHeight', type='DOUBLE', affinity='4', notNull=true, primaryKeyPosition=0, defaultValue='null'}, cupHolderHeight=Column{name='cupHolderHeight', type='DOUBLE', affinity='4', notNull=true, primaryKeyPosition=0, defaultValue='null'}, schoolEntryID=Column{name='schoolEntryID', type='INTEGER', affinity='3', notNull=true, primaryKeyPosition=0, defaultValue='null'}, waterFountApproximation=Column{name='waterFountApproximation', type='DOUBLE', affinity='4', notNull=true, primaryKeyPosition=0, defaultValue='null'}}, foreignKeys=[ForeignKey{referenceTable='SchoolEntry', onDelete='NO ACTION', onUpdate='NO ACTION', columnNames=[schoolEntryID], referenceColumnNames=[cadID]}], indices=[]}
预期的和找到的 SQL 脚本之间存在许多差异；以 cupHolderHeight 列为例：
杯架高度列：
- 预期：
REAL发现：DOUBLE--> 将其更改为 REAL（基本上 SQLite) 中没有 - 预期
notNull=false，发现notNull=true--> 将其更改为 false（即 NULL）
DOUBLE 类型
将其应用于您的迁移 SQL 脚本：
将cupHolderHeight DOUBLE NOT NULL改为cupHolderHeight REAL
您需要浏览其他栏目并执行相同的操作。最终脚本应该是这样的：
database.execSQL("CREATE TABLE WaterFountainEntry (waterFountainID INTEGER PRIMARY KEY AUTOINCREMENT," +
"schoolEntryID INTEGER, waterFountainHeight REAL, cupHolderHeight REAL," +
"waterFountApproximation REAL, FOREIGN KEY (schoolEntryID) REFERENCES SchoolEntry (cadID) ON UPDATE CASCADE ON DELETE CASCADE)");
您还可以考虑
用于排列和比较找到的和预期的脚本：
您可以使用编程脚本对它们进行排序，但这里有一种使用一些工具对它们进行排序的方法：
- 将第一个（预期）复制到文本编辑器中：
TableInfo{name='WaterFountainEntry', columns={waterFountainHeight=Column{name='waterFountainHeight', type='REAL', affinity='4', notNull=false, primaryKeyPosition=0, defaultValue='null'}, waterFountainID=Column{name='waterFountainID', type='INTEGER', affinity='3', notNull=false, primaryKeyPosition=1, defaultValue='null'}, cupHolderHeight=Column{name='cupHolderHeight', type='REAL', affinity='4', notNull=false, primaryKeyPosition=0, defaultValue='null'}, schoolEntryID=Column{name='schoolEntryID', type='INTEGER', affinity='3', notNull=false, primaryKeyPosition=0, defaultValue='null'}, waterFountApproximation=Column{name='waterFountApproximation', type='REAL', affinity='4', notNull=false, primaryKeyPosition=0, defaultValue='null'}}, foreignKeys=[ForeignKey{referenceTable='SchoolEntry', onDelete='CASCADE', onUpdate='CASCADE', columnNames=[schoolEntryID], referenceColumnNames=[cadID]}], indices=[]}
- 用
},\n替换},--> 你必须知道如何在文本编辑器中添加换行符：
TableInfo{name='WaterFountainEntry', columns={waterFountainHeight=Column{name='waterFountainHeight', type='REAL', affinity='4', notNull=false, primaryKeyPosition=0, defaultValue='null'},
waterFountainID=Column{name='waterFountainID', type='INTEGER', affinity='3', notNull=false, primaryKeyPosition=1, defaultValue='null'},
cupHolderHeight=Column{name='cupHolderHeight', type='REAL', affinity='4', notNull=false, primaryKeyPosition=0, defaultValue='null'},
schoolEntryID=Column{name='schoolEntryID', type='INTEGER', affinity='3', notNull=false, primaryKeyPosition=0, defaultValue='null'},
waterFountApproximation=Column{name='waterFountApproximation', type='REAL', affinity='4', notNull=false, primaryKeyPosition=0, defaultValue='null'}},
foreignKeys=[ForeignKey{referenceTable='SchoolEntry', onDelete='CASCADE', onUpdate='CASCADE', columnNames=[schoolEntryID], referenceColumnNames=[cadID]}], indices=[]}
现在每一列都在单独的行中：
- 对另一个（已找到）执行 1 和 2：
TableInfo{name='WaterFountainEntry', columns={waterFountainID=Column{name='waterFountainID', type='INTEGER', affinity='3', notNull=true, primaryKeyPosition=1, defaultValue='null'},
waterFountainHeight=Column{name='waterFountainHeight', type='DOUBLE', affinity='4', notNull=true, primaryKeyPosition=0, defaultValue='null'},
cupHolderHeight=Column{name='cupHolderHeight', type='DOUBLE', affinity='4', notNull=true, primaryKeyPosition=0, defaultValue='null'},
schoolEntryID=Column{name='schoolEntryID', type='INTEGER', affinity='3', notNull=true, primaryKeyPosition=0, defaultValue='null'},
waterFountApproximation=Column{name='waterFountApproximation', type='DOUBLE', affinity='4', notNull=true, primaryKeyPosition=0, defaultValue='null'}},
foreignKeys=[ForeignKey{referenceTable='SchoolEntry', onDelete='NO ACTION', onUpdate='NO ACTION', columnNames=[schoolEntryID], referenceColumnNames=[cadID]}], indices=[]}
- 现在很容易按字母顺序对它们进行排序并将一个值与另一个值进行比较，（Excel 可以作为一种工具）。
获得正确 SQL 的简单技巧是让 Room 为您生成 SQL。
创建实体，然后编译 (Cntrl+F9) 然后查看生成的 java（从 Android 视图），然后查找与@Databaseclass后缀为_Impl，然后找到createAllTables方法，SQL就在那里。这正是 Room 所期望的。
例如:-