Realm not copying database from assets

[AlexLardschneider]

Goal

What do you want to achieve?
Copy a pre-filled database from assets by using .assetFile(context, "default.realm")

Expected Results

Database gets copied and contains all the data

Actual Results

Copied database is only 4kb in size, while the original database in the assets folder is 123kb in size.
Using realm.isEmpty() returns true, which it should not. The Realm Browser for OS X correctly shows all the data in the database. Using realm.where() always returns an empty result.

Steps & Code to Reproduce

RealmConfiguration config = new RealmConfiguration.Builder(context)
.name("default.realm")
.schemaVersion(1)
.assetFile(context, "default.realm")
.deleteRealmIfMigrationNeeded()
.build();

Realm realm = Realm.getInstance(config);
realm.isEmpty() // => true

Using this code, realm.isEmpty() always prints true

Version of Realm and tooling

Realm version(s): 1.0.0

Android Studio version: 2.2 Preview 2

Which Android version and device: CM 13 Android 6.0.1 Galaxy S5 klte

[cmelchior]

Hi @AlexLardschneider
The file will only be copied if one isn't already present. Is there a chance that might be the case?
E.g. during development, files will not be deleted unless you uninstall the app.

[AlexLardschneider]

Hi @cmelchior thanks for the quick response.
Clearing app data or even uninstalling did not solve the issue unfortunately. Also made sure that no database with the same name was already present, which wasn't the case.

[cmelchior]

Hmm, strange. Can you provide a sample project where this fails?
The 4kb is the size of our buffer when copying the file, so it sounds like something is going wrong when it is being copied, but in that case an exception should be thrown. Can you check the log if something seems wrong there?

If that is not the case. Can you provide a sample project with this bug?

[AlexLardschneider]

Scanning the logcat for any errors or messages about realm does not yield and results, nor can I find any exceptions indicating there is something wrong with realm. Will provide a sample project ASAP.

[AlexLardschneider]

So for some reason restarting Android Studio and doing a full project clean & rebuild fixed the issue, as the database is getting copied correctly now and contains all the data. Kinda seems strange to me, but I'll see if I can reproduce this issue and report back.

[AlexLardschneider]

As the problem still exists I send a sample project to help@realm.io.

[cmelchior]

Thanks, I am looking into it.

[cmelchior]

Hi @AlexLardschneider
I found the problem. The Realm Version is 1 in the file you copied and set to 5 in your configuration. This causes a RealmMigrationNeededException to be thrown, but because you set deleteRealmIfMigrationNeeded the file is just deleted and an empty Realm created instead.

This looks like a bug on our part since you are allowed to set a non-zero version number on an empty Realm and copying a existing Realm file is more or less the same thing.