如何从房间数据库中存储和检索图像

Question

I am building a blog application that allows a user to add picture for the blog post. I am currently storing the data as URI string but the issue I have is that the image only shows when I first add it, if I refresh the page or relaunch the application the image will not show, just a blank space with no image.

Database Entity

@Entity
class PostEntity(
    var title: String,
    var body: String,
    var image: String? = null,
    var date: String?

): Serializable {

    @PrimaryKey(autoGenerate = true)
    var id: Int = 0

    var likes:Int? = 0



}

Capturing Images from gallery and camera and converting to URI string

    private fun openCamera(){
        try{
            val CAMERA_REQUEST = 200
            val intent = Intent(MediaStore.ACTION_IMAGE_CAPTURE)
            startActivityForResult(intent, CAMERA_REQUEST)
        }
        catch (e:Exception){
            Toast.makeText(context, "Please try again: ${e.message}", Toast.LENGTH_SHORT).show()
        }

    }

// function to be called in onActivityResult
    private fun loadImage(requestCode: Int, imageView: ImageView, context: Context, data: Intent?){
        if(requestCode == 200){
            try{

                val image = data!!.extras?.get("data") as Bitmap


                imageView.setImageBitmap(image)
                imageView.visibility = View.VISIBLE

                imageUriLoader = getImageUriFromBitmap(context, image)
            }
            catch (e:Exception){
                Toast.makeText(context, "Please try againt: ${e.message}", Toast.LENGTH_SHORT).show()
            }

        }

        else if(requestCode == 201){
            try{
                val imageUri = data!!.data
                imageUriLoader = imageUri
                Picasso.get().load(imageUri).into(imageView)

                imageView.visibility = View.VISIBLE
                imageView.setImageURI(imageUri)

            }
            catch (e:Exception){
                Toast.makeText(context, "Please try again: ${e.message}", Toast.LENGTH_SHORT).show()
            }

        }
        else{
            Toast.makeText(context, "Invalid request", Toast.LENGTH_SHORT).show()
        }
    }

I have seen some post about using blob, most of them are not clear and the fact that blob only allows image size limit of 1MB makes want a better option. Please kindly help with a better to save and restore images.

Answer 1

In your database you should have a field of type String (or the equivalent VARCHAR etc.) that serves as image path inside a directory of your choice, so for example

Then you can add whatever fields you need, for example in your case you would need a userID that serves as a foreign key to the user logged in. So as soon as the user loads an image you save the file to the path you desire and then save that same path inside the db so that next time the user loggs in you look up his image path and then load it on the web page.