How To: Store type safe Key/Value Pairs in EF Core

I know it's a bit late for an answer, but I had the same problem trying to persist keyvalue pairs. The only way I found was to strong type them, since EF has no clue on how to persist the KeyValue entity.

Here's my model:

public class Payment
{
    //-- Properties
    public int PaymentId { get; set; }
    public decimal Amount { get; set; }
    public string Currency { get; set; }

    public virtual List<PaymentField> PaymentFields { get; set; } = new List<PaymentField>();        
}

public class PaymentField
{
    //-- Properties
    [Key]
    public int PaymentFieldId { get; set; }

    // References master table
    public int PaymentId { get; set; }
    public virtual Payment Payment { get; set; }
    public virtual List<PaymentFieldItem> PaymentFieldItems { get; set; } = new List<PaymentFieldItem>();
}

public class PaymentFieldItem
{
    public int PaymentFieldItemId { get; set; }
    public string Name { get; set; }
    public string Value { get; set; }

    public int PaymentFieldId { get; set; }
    public virtual PaymentField PaymentField { get; set; }
}

Hope you can adjust to your own needs.