TypeConverters
When building out Model
classes, you may wish to provide a different type of @Column
that from the standard supported column types. To recap the standard column types include:
1. String
, char
, Character
2. All numbers types (primitive + boxed)
3. byte[]
/Byte
4. Blob
(DBFlow's version)
5. Date
/java.sql.Date
6. Booleans
7. Model
as @ForeignKey
or @ColumnMap
8. Calendar
9. BigDecimal
10. UUID
TypeConverter
do not support:
1. Any Parameterized fields.
2. List<T>
, Map<T>
, etc. Best way to fix this is to create a separate table relationship
3. Conversion from one type-converter to another (i.e JSONObject
to Date
). The first parameter of TypeConverter
is the value of the type as if it was a primitive/boxed type.
4. Conversion from custom type to Model
, or Model
to a supported type.
5. The custom class must map to a non-complex field such as String
, numbers, char
/Character
or Blob
Define a TypeConverter
Defining a TypeConverter
is quick and easy.
This example creates a TypeConverter
for a field that is JSONObject
and converts it to a String
representation:
Once this is defined, by using the annotation @TypeConverter
, it is registered automatically across all databases.
There are cases where you wish to provide multiple TypeConverter
for same kind of field (i.e. Date
with different date formats stored in a DB). You can override a field's TypeConverter
locally at the @Column
level.
TypeConverter for specific @Column
@Column
In DBFlow, specifying a TypeConverter
for a @Column
is as easy as @Column(typeConverter = JSONConverter::class)
. What it will do is create the converter once for use only when that column is used.
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