迁移到房间，应用程序在启动时崩溃，异常

Question

以下是该应用的代码： https://github.com/sandy-8925/Checklist/tree/room_db

当我构建并启动它时，应用程序始终崩溃并出现以下异常。请注意，我已经使用普通的Sqlite DB

获得了此应用程序的先前版本

  

引起：java.lang.IllegalStateException：迁移不正确   处理项目（org.sanpra.checklist.activity.ChecklistItem）。                                                                          预期：                                                                         TableInfo {name ='items'，columns = {checked = Column {name ='checked'，   type ='INTEGER'，notNull = true，primaryKeyPosition = 0}，   _id =列{name ='_ id'，type ='INTEGER'，notNull = true，primaryKeyPosition = 1}，desc = Column {name ='desc'，type ='TEXT'，   notNull = false，primaryKeyPosition = 0}}，foreignKeys = []，indices = []}                                                                          实测：                                                                         TableInfo {name ='items'，columns = {checked = Column {name ='checked'，   type ='integer'，notNull = true，primaryKeyPosition = 0}，   _id =列{name ='_ id'，type ='integer'，notNull = false，primaryKeyPosition = 1}，desc = Column {name ='desc'，type ='text'，   notNull = true，primaryKeyPosition = 0}}，foreignKeys = []，indices = []}

     

在   org.sanpra.checklist.dbhelper.ItemsDatabase_Impl $ 1.validateMigration（ItemsDatabase_Impl.java:66）                                                                             在   android.arch.persistence.room.RoomOpenHelper.onUpgrade（RoomOpenHelper.java:75）                                                                             在   android.arch.persistence.db.framework.FrameworkSQLiteOpenHelper $ OpenHelper.onUpgrade（FrameworkSQLiteOpenHelper.java:118）                                                                             在   android.database.sqlite.SQLiteOpenHelper.getDatabaseLocked（SQLiteOpenHelper.java:299）                                                                             在   android.database.sqlite.SQLiteOpenHelper.getWritableDatabase（SQLiteOpenHelper.java:194）                                                                             在   android.arch.persistence.db.framework.FrameworkSQLiteOpenHelper $ OpenHelper.getWritableSupportDatabase（FrameworkSQLiteOpenHelper.java:93）                                                                             在   android.arch.persistence.db.framework.FrameworkSQLiteOpenHelper.getWritableDatabase（FrameworkSQLiteOpenHelper.java:54）                                                                             在   android.arch.persistence.room.RoomDatabase.query（RoomDatabase.java:193）                                                                             在   org.sanpra.checklist.activity.ItemsDao_Impl.fetchAllItems（ItemsDao_Impl.java:229）                                                                             在   org.sanpra.checklist.activity.ChecklistItemsCursorLoader.loadInBackground（ChecklistItemsCursorLoader.java:46）                                                                             在   org.sanpra.checklist.activity.ChecklistItemsCursorLoader.loadInBackground（ChecklistItemsCursorLoader.java:32）                                                                             在   android.support.v4.content.AsyncTaskLoader.onLoadInBackground（AsyncTaskLoader.java:306）                                                                             在   android.support.v4.content.AsyncTaskLoader $ LoadTask.doInBackground（AsyncTaskLoader.java:59）                                                                             在   android.support.v4.content.AsyncTaskLoader $ LoadTask.doInBackground（AsyncTaskLoader.java:47）                                                                             在   android.support.v4.content.ModernAsyncTask $ 2.call（ModernAsyncTask.java:138）                                                                             在java.util.concurrent.FutureTask.run（FutureTask.java:266）

Answer 1

预期

  

TableInfo {name ='items'，columns = {checked = Column {name ='checked'，   type ='INTEGER'，notNull = true，primaryKeyPosition = 0}，   _id =列{name ='_ id'，type ='INTEGER'， notNull = true ，primaryKeyPosition = 1}，desc = Column {name ='desc'，type ='TEXT'，    notNull = false ，primaryKeyPosition = 0}}，foreignKeys = []，indices = []}

实测值

  

TableInfo {name ='items'，columns = {checked = Column {name ='checked'，   type ='integer'，notNull = true，primaryKeyPosition = 0}，   _id =列{name ='_ id'，type ='integer'， notNull = false ，primaryKeyPosition = 1}，desc =列{name ='desc'，type ='text'，    notNull = true ，primaryKeyPosition = 0}}，foreignKeys = []，indices = []}

_id可以为空，但是Room期望它不为空。

desc不为null但是Room期望它为null