DataTransformer (ObjectBox Java 4.0.3 API)

Type Parameters:

FROM - Data type this transformer receives

TO - Type of transformed data
```
public interface DataTransformer<FROM,TO>
```
Transforms or processes data before it is given to subscribed DataObservers. A transformer is set via SubscriptionBuilder.transform(DataTransformer).
Note that a transformer is not required to actually "transform" any data. Technically, it's fine to return the same data it received and just do some processing with it.
Threading notes: transformations are executed sequentially on a background thread owned by the subscription publisher. It is OK to perform long lasting operations, however this will block notifications to all other observers until finished.

- Method Summary
  
  All Methods Instance Methods Abstract Methods
  Modifier and Type Method Description
  
  TO transform(FROM source)
  Transforms/processes the given data.

- Method Detail
  - transform
```
TO transform(FROM source)
      throws java.lang.Exception
```
    Transforms/processes the given data.
    
    Parameters:
    
    source - data to be transformed
    
    Returns:
    
    transformed data
    
    Throws:
    
    java.lang.Exception - Transformers may throw any exceptions, which can be reacted on via SubscriptionBuilder.onError(ErrorObserver).