TypeConverters.md

Type Converters

Type converters enable fields within a Model that are not necessarily database-typed. They convert the value of the field into a database type in the way that you can define. They also define the way that when a Model is loaded, we recreate the field using the converter. Note: TypeConverter can only be regular Column, not PrimaryKey or ForeignKey due to the non-determinate mapping of data.

These converters are shared across all databases.

If we specify the model value as a Model class then, there may be some very unexpected behavior for fields that are defined as Column.FOREIGN_KEY

Here is the implementation of LocationConverter, converting Locations into Strings:

  // First type param is the type that goes into the database
  // Second type param is the type that the model contains for that field.
  @com.raizlabs.android.dbflow.annotation.TypeConverter
  public class LocationConverter extends TypeConverter<String,Location> {

    @Override
    public String getDBValue(Location model) {
        return model == null ? null : String.valueOf(model.getLatitude()) + "," + model.getLongitude();
    }

    @Override
    public Location getModelValue(String data) {
        String[] values = data.split(",");
        if(values.length < 2) {
            return null;
        } else {
            Location location = new Location("");
            location.setLatitude(Double.parseDouble(values[0]));
            location.setLongitude(Double.parseDouble(values[1]));
            return location;
        }
    }
  }

To use the LocationConverter, using TypeConverters we simply add the class as a field in our table:

@Table(...)
public class SomeTable extends BaseModel {


  @Column
  Location location;

}

Column Specific TypeConverters

As of 3.0, TypeConverter can be used on a column-by-column basis.

@Table(...)
public class SomeTable extends BaseModel {


  @Column(typeConverter = SomeTypeConverter.class)
  Location location;

}

NOTE: enum classes that want to change from the default enum conversion (from enum to String), you must define a Custom Type Converter for the column.