Ever since I came across Realm, I've loved it. It's fast, easy to use, no hassle to set up, easy migrations. Since the time I started using it they've added fantastic, automatic syncing with a backend. And the next thing on the horizon is a cloud service for the backend, so you don't have to run it yourself (yay!).
While there's a lot to love about Realm, there are of course some limitations. One of those limitations is that it's that you're only able to store primitive types (like int
, string
, DateTimeOffset
, etc). This has to do with the way Realm stores and reads data from the database.
One of the types you're not able to store are enum
s. But as I've mentioned, you're able to store int
s in Realm, and an enum
is like an int
in a clever disguise.
The values of an enum
are automatically assigned an int
value starting at 0
. The first value declared is assigned 0
, the second is assigned 1
, the third is assigned 2
and so on. Like indexes in an array.
Let's define an enum
:
public enum Color
{
Blue, Green, Red, Yellow
}
Then you're able to explicitly cast between enum
s and int
s like this:
Color color = Color.Blue;
int colorInt = (int)color; // == 0
colorInt = (int)Color.Green; // == 1
color = (Color)1; // == Color.Green
As we can easily cast between Color
and int
, we can also store Color
as an int
in Realm.
Let's say we have a Paint
class on which one of the properties is the color of the paint:
public class Paint : RealmObject
{
// Other code
public int Color { get; set; }
}
That works, but it's a bit clunky having to always cast the int
whenever we want to use it. Not to worry though. We'll rename Color
to ColorRaw
to indicate that it stores a raw value, instead of the desired one. We'll also add a new property named Color
which casts the int
for us:
public class Map : RealmObject
{
// Other code
public int ColorRaw { get; set; }
public Color Color
{
get => (Color)ColorRaw;
set => ColorRaw = (int)value;
}
}
As we've specified a custom getter and setter on Color
, Realm will ignore the property and not store it in the database.
Now we'll be able to use it (mostly) as we normally would. You won't be able to data bind to Color
, for instance. You can either make it send PropertyChanged
notification yourself, or use a converter on your binding to convert between the int
and a Color
.
Hope this little trick helps you out.
Happy coding!
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