How insert image in room persistence library?

Question

I am using room persistence library for my android application, Now I have to insert image in my db. I successfully define @Entity for the primitive data type. and also through converter class, i stored all object, date, time. Now I have to store Image. I am not able to understand how we define Column info and entity and how we insert that data as well as read data from the table.

What is the maximum size of data which inserted into the single row? What is max and min size of data in one field in Android SQLite?

Answer 1

It is usually not recommended to store image data into the database. But however if it is required for your project then you can do so.

Image data are usually stored into db using BLOB data type, Room also provide support for BLOB data type Documentation

You can declare your entity class as mentioned below to store Image data.

@Entity(tableName = "test")
public class Test{

@PrimaryKey
@ColumnInfo(name = "_id")
private int id;

@ColumnInfo(typeAffinity = ColumnInfo.BLOB)
private byte[] image;
}

Answer 2

As Pinakin mentioned, it is not recommended to store an image into database and file path would be better but if it is required to store image I would suggest compress the image to below 2 MB (here is an example) to avoid breaking app. Room supports BLOB for image. Entity class in kotlin:

ImageTest.kt

 @Entity    
 class ImageTest {

        @PrimaryKey(autoGenerate = true)

        var id: Int = 1

        @ColumnInfo(typeAffinity = ColumnInfo.BLOB)
        var data: ByteArray? = null
      }

ImageDao.kt

 @Dao
 interface ImageTestDao {

       @Insert(onConflict = OnConflictStrategy.REPLACE)
       fun upsertByReplacement(image: List<ImageTest>)

       @Query("SELECT * FROM image")
       fun getAll(): List<ImageTest>

       @Query("SELECT * FROM image WHERE id IN (:arg0)")
       fun findByIds(imageTestIds: List<Int>): List<ImageTest>

       @Delete
       fun delete(imageTest: ImageTest)
   }

Databse.kt

 import android.arch.persistence.room.Database
 import android.arch.persistence.room.RoomDatabase
 import android.arch.persistence.room.TypeConverters

   @Database(entities = arrayOf(ImageTest::class), version = 1)
   @TypeConverters(DataConverters::class)
   abstract class Database : RoomDatabase() {
    abstract fun getImageTestDao(): ImageTestDao
   }
    

In DatabaseHelper something like

  class DatabaseHelper(context: Context) {

   init {
        DatabaseHelper.context = WeakReference(context)
        }

   companion object {
    
   private var context: WeakReference<Context>? = null
   private const val DATABASE_NAME: String = "image_test_db"
   private var singleton: Database? = null

   private fun createDatabase(): Database {
       return Room.databaseBuilder(context?.get() ?:
               throw IllegalStateException("initialize by calling  
               constructor before calling DatabaseHelper.instance"),
               Database::class.java,
               DATABASE_NAME)
               .build()
   }


   val instance: Database
       @Synchronized get() {
           if (null == singleton)
               singleton = createDatabase()

           return singleton as Database
       }

     fun setImage(img: Bitmap){
     val dao = DatabaseHelper.instance.getImageTestDao() 
     val imageTest = ImageTest()
     imageTest.data = getBytesFromImageMethod(image)//TODO
     dao.updsertByReplacement(imageTest)

     fun getImage():Bitmap?{
     val dao = DatabaseHelper.instance.getImageTestDao() 
     val imageByteArray = dao.getAll()
     return loadImageFromBytes(imageByteArray[0].data)
     //change accordingly 
     }

Correct me if I am wrong. Hope this helps someone out there

Answer 3

Save the image as a file and save the file path Uri to Room

As seen in CameraX's image capture use case, when a photo is successfully taken, the File path reference Uri, savedUri, can be retrieved safely.

Then, the Uri can be converted to a string with savedUri.toString(), and saved to Room.

• It's important to ensure the Room file reference is also updated if the file is moved or deleted.
• The image String saved in Room may need to be converted back into a Uri to be displayed with an image library such as Glide with Uri.parse(someString).

In the CameraX sample, an image path's Uri can safely be obtained in onImageSaved.

• It would then be saved into Room off of the main thread using Kotlin Coroutines or RxJava, preferably in a ViewModel or somewhere that handles the business logic separate from the view logic.

Getting Started with CameraX > 5. Implement ImageCapture use case

private fun takePhoto() {
   // Get a stable reference of the modifiable image capture use case
   val imageCapture = imageCapture ?: return

   // Create time-stamped output file to hold the image
   val photoFile = File(
       outputDirectory,
       SimpleDateFormat(FILENAME_FORMAT, Locale.US
       ).format(System.currentTimeMillis()) + ".jpg")

   // Create output options object which contains file + metadata
   val outputOptions = ImageCapture.OutputFileOptions.Builder(photoFile).build()

   // Set up image capture listener, which is triggered after photo has
   // been taken
   imageCapture.takePicture(
       outputOptions, ContextCompat.getMainExecutor(this), object : ImageCapture.OnImageSavedCallback {
           override fun onError(exc: ImageCaptureException) {
               Log.e(TAG, "Photo capture failed: ${exc.message}", exc)
           }

           override fun onImageSaved(output: ImageCapture.OutputFileResults) {
               val savedUri = Uri.fromFile(photoFile)
               val msg = "Photo capture succeeded: $savedUri"
               Toast.makeText(baseContext, msg, Toast.LENGTH_SHORT).show()
               Log.d(TAG, msg)
           }
       })
}

This strategy is outlined in Saving image in Room database on Reddit.

Cloud Storage

Creating a file for the image and saving the file path in Room covers local storage. In order to ensure the images are saved across multiple devices or when if data cache and data are cleared, a form of Cloud Storage is needed to upload the files to and to download and sync with the local storage.