android-room

问题 So I have let's say pretty complex database which is using many to many database design with foreign keys and join tables and it's Room database. I want to create backup system for it because it's offline application I would need to export database and store it to google drive's app folder. I have read quite a lot about it in recent day's but still a bit confused I saw that there is ways to export database as CSV , JSON , excel files or just as .db file, but what are the best practices for

问题 I know that sqlite does not support Boolean and we need to use int columns to mimic the behavior of Boolean . But does Room support Boolean ? What if have a Boolean in my entity ? Will it work as expected? 回答1: Yes it does. When you store boolean using room, it automatically stores 1 for true and 0 for false . And same case while reading. It converts 1 or 0 to true/ false respectively. 来源： https://stackoverflow.com/questions/51130777/does-room-database-support-boolean-variables-in-entity

问题 I know that sqlite does not support Boolean and we need to use int columns to mimic the behavior of Boolean . But does Room support Boolean ? What if have a Boolean in my entity ? Will it work as expected? 回答1: Yes it does. When you store boolean using room, it automatically stores 1 for true and 0 for false . And same case while reading. It converts 1 or 0 to true/ false respectively. 来源： https://stackoverflow.com/questions/51130777/does-room-database-support-boolean-variables-in-entity

问题 I know that sqlite does not support Boolean and we need to use int columns to mimic the behavior of Boolean . But does Room support Boolean ? What if have a Boolean in my entity ? Will it work as expected? 回答1: Yes it does. When you store boolean using room, it automatically stores 1 for true and 0 for false . And same case while reading. It converts 1 or 0 to true/ false respectively. 来源： https://stackoverflow.com/questions/51130777/does-room-database-support-boolean-variables-in-entity

问题 App Database has Items table with a column Price with datatype Long . Db Version = 1 CREATE TABLE items (_id INTEGER PRIMARY KEY AUTOINCREMENT,item_id INTEGER,title TEXT,price LONG, UNIQUE (item_id) ON CONFLICT IGNORE) While trying to migrate to Room I am experiencing below issue java.lang.IllegalStateException: Migration didn't properly handle items(moka.pos.test.data.entity.Item). Expected : price=Column{name='price', type='INTEGER', affinity='3', notNull=false, primaryKeyPosition=0} Found

问题 Sorry if my title did not match to what my questions is. I have created a Android Library, in which I have a Room database, As there should be only one instance of Room database, I have OfflineDatabaseManager getInstance method which provides the instance to the Android project which accesses it by passing the context. I have context within the Android project and I can pass it. I want to listen to changes happening on the database table within the library so I can do something with it, I

问题 I have used Android Room Database to create my app, I am filling records of students, I want to retrieve page number of the latest record that I have entered from the Room Database when I select student's name. This is my code below DOA @Dao public interface NewRecordDAO { @Insert(onConflict = REPLACE) public void addRecord(NewRecord... newRecord); @Update(onConflict = REPLACE) public void updateRecord(NewRecord newRecord); @Delete public void deleteRecord(NewRecord newRecord); @Query("DELETE

问题 I didn't find any answer to what I'm searching for so I'm sending this question. I am using Room for Android. I have an Entity with an Int column and I need to change it to Double, and I don't know how to do it. Does anybody know how to do it? My question might be dumb, but I didn't find any answer on stackoverflow/any google search. 回答1: You need to create new table with the new schema. Copy data from old table to the new one. Drop old table. Rename new table to the name of old table. Here

问题 This is my query: and here, when I retrive it, the value is null : I have debugged my database and the data is there: This is my entity object : I have investigated the database query, but couldn't figure what's wrong 回答1: Your Query returns a LiveData . You will have to observe the changes. Initially, the value is null before the query. After the query, the list dataset changes and it will return you the desired correct values. Assuming ViewModel class is something like this: class

问题 GreenDAO supports DaoMaster.dropAllTables() and DaoMaster.createAllTables(). I'm looking for similar functionality in RoomDB. Does RoomDB supports this functionality ?? The use-case for this functionality is, when the user tries to login with new mobile number to my app, i want to clear the data of old login number by showing a warning dialog message and allow login with new number. 回答1: Room supports dropping and creating tables only during a migration between schema versions. You can gain