com.datastax.oss.driver.api.mapper.annotations

Annotation Type SchemaHint

@Target(value=TYPE)
 @Retention(value=RUNTIME)
public @interface SchemaHint

This annotation could be used only on a class that is annotated with @Entity annotation. The logic will be applied only, if you are running mapper withSchemaValidationEnabled(true).

Example:

 @Entity
 @SchemaHint(targetElement = @SchemaHint.TargetElement.TABLE)
 public class Product {
   // fields of the entity
 }
 

By default, if you will create an @Entity without the @SchemaHint annotation, the following logic will be applied when doing validation:

1. Check if the given entity is a Table, if it is - validates if all fields of the Entity are present in the CQL table.
2. If it is not a table, check if the given entity is a UDT. If this is a case check if all Entity fields are present in the CQL UDT type.
3. If there is not information about Table or UDT it means that the given @Entity has no corresponding CQL definition and error is generated.

If you want the mapper to generate code only to check the path for UDT or Table you can provide the @SchemaHint on the Entity:

1. If you will set the targetElement = TABLE, then only the code path for checking CQL TABLE will be generated. If there is no corresponding CQL Table, then there is no check of UDT. The code throws an Exception denoting that CQL Table is missing for this Entity.
2. If you will set the targetElement = UDT, then only the code path for checking CQL UDT will be generated. If there is no corresponding CQL UDT type, the code throws an Exception denoting that CQL UDT is missing for this Entity.

Required Element Summary

Required Elements

Modifier and Type	Required Element and Description
SchemaHint.TargetElement	targetElement

Element Detail

targetElement

public abstract SchemaHint.TargetElement targetElement