Saving Nested Objects to Realm Database in .Net

Question

I'm new to realm and I'm having a lot of trouble getting a nested object to save. I can save the parent, but I get a Realms.Exceptions.RealmObjectManagedByAnotherRealmException saying Cannot start to manage an object with a realm when it's already managed by another realm. I only have one realm and I'm creating a new object!

This is what the parent class looks like:

public class Transaction : RealmObject
{
    [PrimaryKey]
    public string ID { get; set; } = Guid.NewGuid().ToString();
    ...
    public IList<TransactionDetails> Rows { get; }

}

and here is the child:

public class TransactionDetails : RealmObject
{
    [PrimaryKey]
    public string ID { get; set; } = Guid.NewGuid().ToString();
    public Account Account { get; set; } = new Account();
    public double Amount { get; set; }
    ...
}

In the constructor for the class where I'm trying to save the object I have realm = Realm.GetInstance( config );.

This is my latest attempt in which I tried to write the details in a separate write transaction but it didn't work.

var transaction = new Models.Transaction();
...

realm.Write( () => realm.Add( transaction, update: true ) );

foreach ( var details in Trans.Rows )
{
    var row = new TransactionDetails();
    ...

    //realm.Add( details );
    //realm.Write( () => realm.Add( details ) );
    realm.Write( () => transaction.Rows.Add( details ) ); // Error here every time           
}

The documentation wasn't helpful at all.

Answer 1

You only need to do the write once.

var transaction = new Models.Transaction();
...

foreach ( var details in Trans.Rows )
{
    var row = new TransactionDetails();
    ...

    transaction.Rows.Add( details ); // Error here every time           
}

realm.Write( () => realm.Add( transaction, update: true ) );

You would be better off wrapping this in a transaction.

using (Transaction _transaction = realm.BeginWrite())
{
    var trans = new Models.Transaction();
    ...

    realm.Add(trans);

    foreach ( var details in Trans.Rows )
    {
        var row = new TransactionDetails();
        ...

        trans.Rows.Add( details ); // Error here every time           
    }
    _transaction.Commit();
}

I have written an app using Realm and Xamarin Forms. Code is released on GitHub, https://github.com/rsatter/PRO-PD/tree/master/PRO-PD.