Transform an object to a list[object] in Realm as migration ( How can i replace a list[objects] with object field in Realm? )

Question

I want to import existing token into tokenList as first item , for example if someone has a token=\"abc\" after migration

Answer 1

I created new issue in Realm GitHub then i found right way for transform object to list[object] in Realm and insert existing object from previous version to new version of application.

In this example we want to transform Token object to tokenList[Token] in Bank model.

In last version of migration put this :

public class RealmMigration implements io.realm.RealmMigration {

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        if (oldVersion == 3) {
            //Create a schema for Bank
            final RealmObjectSchema bankSchema = realmSchema.get("Bank");
            //Create a schema for Token that has been in Bank model
            final RealmObjectSchema tokenSchema = realmSchema.get("Token");
            //We use bankSchema for add tokenList field and transform
            bankSchema
                .addRealmListField("tokenList", tokenSchema)
                .transform((obj) -> {//obj is bank model,we have a transform in bank model
                         DynamicRealmObject token = obj.get("Token");
                         List<DynamicRealmObject> tokenList = obj.get("tokenList");
                                //We add token from pre version to tokenList in new version
                                if (token != null) tokenList.add(token);
                            }
                    )
                    //Finally remove unwanted field
                    .removeField("Token");
        }
}