com.datastax.oss.driver.api.mapper.annotations.QueryProvider Maven / Gradle / Ivy
/*
* Copyright DataStax, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.datastax.oss.driver.api.mapper.annotations;
import com.datastax.oss.driver.api.mapper.MapperBuilder;
import com.datastax.oss.driver.api.mapper.MapperContext;
import com.datastax.oss.driver.api.mapper.entity.EntityHelper;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
/**
* Annotates a {@link Dao} method that delegates the execution of the query to a user-provided
* class.
*
* Example:
*
*
* @Dao
* public interface SensorDao {
* @QueryProvider(providerClass = FindSliceProvider.class, entityHelpers = SensorReading.class)
* PagingIterable<SensorReading> findSlice(int id, Integer month, Integer day);
* }
*
* public class FindSliceProvider {
* public FindSliceProvider(
* MapperContext context, EntityHelper<SensorReading> sensorReadingHelper) {
* ...
* }
*
* public PagingIterable<SensorReading> findSlice(int id, Integer month, Integer day) {
* ... // implement the query logic here
* }
* }
*
*
* Use this for requests that can't be expressed as static query strings, for example if some
* clauses are added dynamically depending on the values of some parameters.
*
*
The parameters and return type are completely free-form, as long as they match those of the
* provider method.
*
* @see MapperBuilder#withCustomState(Object, Object)
*/
@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface QueryProvider {
/**
* The class that will execute the query.
*
*
The mapper will create an instance of this class for each DAO instance. It must expose a
* constructor that is accessible from the DAO interface's package, and takes the following
* parameter types:
*
*
* - {@link MapperContext}.
*
- zero or more {@link EntityHelper}s, as defined by {@link #entityHelpers()}.
*
*
* It must also expose a method that will be invoked each time the DAO method is called, see
* {@link #providerMethod()}.
*/
Class providerClass();
/**
* The method to invoke on the provider class.
*
* It must be accessible from the DAO interface's package, and have the same parameters and
* return type as the annotated DAO method.
*
*
This is optional; if not provided, it defaults to the name of the annotated DAO method.
*/
String providerMethod() default "";
/**
* A list of entities for which {@link EntityHelper} instances should be injected into the
* provider class's constructor (in addition to the mapper context).
*
*
For example, if {@code entityHelpers = {Product.class, Dimensions.class}}, your provider
* class must expose a constructor that takes the parameter types{@code (MapperContext,
* EntityHelper, EntityHelper)}.
*
* All provided classes must be annotated with {@link Entity}. Otherwise, the mapper will issue
* a compile-time error.
*/
Class[] entityHelpers() default {};
}