Xamarin Form Create Table Problem in SqLite based complex class

Question

I develop cross platform mobile app on Xamarin Forms. I try to create tables in sqlite. My class name is 'News' and News class containts 'Country' class.

Create table code and class is like below.

    [Serializable]
    [DataContract]
    public class News
    {
        [PrimaryKey]
        [DataMember]
        public int Id { get; set; }
        [DataMember]
        public Guid ActivityId { get; set; }
        [DataMember]
        public int Type { get; set; }
        [DataMember]
        public string Title { get; set; }
        [DataMember]
        public CountryBase Country { get; set; }
    } 

and code is something like

var db = new SQLiteConnection (dbPath);
db.CreateTable<News> ();

This isn't working. When i remove the country class it works. I try to create country table separately but still i couldn't create News table. How can i fix the problem?

Answer 1

The SQLite doesn't allow relationships, and public CountryBase Country { get; set; } is interpreted as one.

So you need:

either to serialize your Country as a string before inserting, and you will have this:

[DataMember]
public string SerializedCountry { get; set; }

[Ignore]
public CountryBase Country { get; set; }

And you need to handle serialization with Json.net manually of the Country.

Or create another Country table, and specify its id in your entity definition:

[Serializable]
[DataContract]
public class News
{
    [PrimaryKey]
    [DataMember]
    public int Id { get; set; }
    [DataMember]
    public Guid ActivityId { get; set; }
    [DataMember]
    public int Type { get; set; }
    [DataMember]
    public string Title { get; set; }
    [DataMember]
    public int CountryId { get; set; }
} 


[Serializable]
[DataContract]
public class Country
{
    [PrimaryKey]
    [DataMember]
    public int Id { get; set; }
    [DataMember]
    public string Name { get; set; }
    ...
}