[Realm SYNC] Do I need a partner collection for a non-destructive change?.

[vardansargsyan92]

Hello.

Imagine that we have a Person object in my realm database:

public class Person : RealmObject
{
    [PrimaryKey]
    [MapTo("_id")]
    public ObjectId Id { get; set; }

    public string FirstName { get; set; }
    public string LastName { get; set; }
    public int Age { get; set; }
}

Then I decide to use combined FullName property instead of the separate FirstName and LastName property in the Person schema.

public class Person : RealmObject
{
    [PrimaryKey]
    [MapTo("_id")]
    public ObjectId Id { get; set; }

    public string FullName { get; set; }
    public int Age { get; set; }
}

According to the doc this change isn't destructive and I don't have to create a partner collection, forward and backward migration functions.

But the problem is that I would like to migrate the realm to conform to the updated Person schema. If I were developing an application without Realm Sync, I would use the following migration function:

 var config = new RealmConfiguration
{
    SchemaVersion = 4,
    MigrationCallback = (migration, oldSchemaVersion) =>
    {
        var oldPeople = migration.OldRealm.All<Person>();
        var newPeople = migration.NewRealm.All<Person>();

        // Migrate Person objects
        for (var i = 0; i < newPeople.Count(); i++)
        {
            var oldPerson = oldPeople.ElementAt(i);
            var newPerson = newPeople.ElementAt(i);

            // Changes from version 1 to 2 (adding LastName) will occur automatically when Realm detects the change

            // Migrate Person from version 2 to 3: replace FirstName and LastName with FullName
            // LastName doesn't exist in version 1
            if (oldSchemaVersion < 2)
            {
                newPerson.FullName = oldPerson.FirstName;
            }
            else if (oldSchemaVersion < 3)
            {
                newPerson.FullName = $"{oldPerson.FirstName} {oldPerson.LastName}";
            }
        }
    }
};
var realm = Realm.GetInstance(config);

and that would be enough to extract the FullName from older databases combining the FirstName and LastName properties.

So I have the following questions:

1. Do I need a partner collection for that changes?
2. Does the non-sync realm migration function applicable for the realm sync? And if No what I should do in that case?

[ianpward]

hey @vardansargsyan92 can you move this question to forums.realm.io please and ping me? I can get someone to respond. In general the github repo's are for non-sync related bugs - for design and implementation questions related to sync please use the forums.

[vardansargsyan92]

hi @ianpward. Unfortunately I am not able to move it to forums because I am not able to sign in. When I try to log in to system it's says Sorry, you can't access Community Forums (New) because you are not assigned this app in Okta. If you're wondering why this is happening, please contact your administrator.

[vardansargsyan92]

@ianpward seems the issue has been fixed. So here is a question