Realm react native schema versioning - react-native

Question

I have the following 2 schemas in realm.js file
class Bill extends Realm.Object {}
Bill.schema = {
name: 'Bill',
primaryKey: 'id',
properties: {
id: { type: 'string', indexed: true },
year: 'int',
month: 'int',
description: 'string',
dateCreated: 'int',
}
};
class User extends Realm.Object {}
User.schema = {
name: 'User',
primaryKey: 'id',
properties: {
id: 'string',
name: 'string?',
email: 'string?'
}
};
const realm = new Realm({schema: [Bill, User]});
export default realm;
this works perfectly when I first release my app to AppStore or PlayStore.
I need to change both schema and release to AppStore or PlayStore again and I need to handle both new installation or update of my app where the schema change to following
class Bill extends Realm.Object {}
Bill.schema = {
name: 'Bill',
primaryKey: 'id',
properties: {
id: { type: 'string', indexed: true },
year: 'int',
month: 'int',
description: 'string',
dateCreated: 'int',
dateDeleted: 'int',
}
};
class User extends Realm.Object {}
User.schema = {
name: 'User',
primaryKey: 'id',
properties: {
id: 'string',
name: 'string?',
email: 'string?',
photoUrl: 'string?',
}
};
by adding one more field in each schema.
So how should I configure my realm schema version?
Should I configure like below:
const realm = new Realm([
{schema: Bill, schemaVersion: 1},
{schema: User, schemaVersion: 1}
]);
But this may crash for new installation.

Answer 1

You should set global schemaVersion for all database, not for each model. And perform migrations to the current version, like it's described in the docs:
You define a migration and the associated schema version by updating
the schemaVersion and defining an optional migration function. Your
migration function provides any logic needed to convert data models
from previous schemas to the new schema. When opening a Realm the
migration function will be applied to update the Realm to the given
schema version only if a migration is needed.
If no migration function is supplied then any new properties an
automatically added and old properties are removed from the database
when updating to the new schemaVersion. If you need to update old or
populate new properties when upgrading your version you can do this in
the migration function. For example, suppose we want to migrate the
Person model declared earlier. You can populate the name property of
the new schema using the old firstName and lastName properties:
Realm.open({
schema: [PersonSchema],
schemaVersion: 1,
migration: (oldRealm, newRealm) => {
// only apply this change if upgrading to schemaVersion 1
if (oldRealm.schemaVersion < 1) {
const oldObjects = oldRealm.objects('Person');
const newObjects = newRealm.objects('Person');
// loop through all objects and set the name property in the new schema
for (let i = 0; i < oldObjects.length; i++) {
newObjects[i].name = oldObjects[i].firstName + ' ' + oldObjects[i].lastName;
}
}
}
}).then(realm => {
const fullName = realm.objects('Person')[0].name;
});
Once the migration is successfully completed the Realm and all of its
objects can be accessed as usual by your app.