com.datastax.oss.driver.api.mapper.annotations.Delete 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.core.CqlIdentifier;
import com.datastax.oss.driver.api.core.cql.AsyncResultSet;
import com.datastax.oss.driver.api.core.cql.BoundStatement;
import com.datastax.oss.driver.api.core.cql.ResultSet;
import com.datastax.oss.driver.api.core.session.Session;
import com.datastax.oss.driver.api.core.session.SessionBuilder;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.CompletionStage;
import java.util.function.Function;
import java.util.function.UnaryOperator;
/**
* Annotates a {@link Dao} method that deletes an instance of an {@link Entity}-annotated class.
*
* Example:
*
*
* @Dao
* public interface ProductDao {
* @Delete
* void delete(Product product);
* }
*
*
* Parameters
*
* The method can operate either on an entity instance, or on a primary key (partition key +
* clustering columns).
*
* In the latter case, the parameters must match the types of the primary key columns, in the
* exact order (which is defined by the integer values of the {@link PartitionKey} and {@link
* ClusteringColumn} annotations in the entity class). The parameter names don't necessarily need to
* match the names of the columns. In addition, because the entity class can't be inferred from the
* method signature, it must be specified in the annotation with {@link #entityClass()}:
*
*
* @Delete(entityClass = Product.class)
* void deleteById(UUID productId);
*
*
* An {@linkplain #customIfClause() optional IF clause} can be appended to the generated query. It
* can contain placeholders, for which the method must have corresponding parameters (same name, and
* a compatible Java type):
*
*
* @Delete(entityClass = Product.class, customIfClause = "description = :expectedDescription")
* ResultSet deleteIfDescriptionMatches(UUID productId, String expectedDescription);
*
*
* A {@link Function Function<BoundStatementBuilder, BoundStatementBuilder>} or {@link
* UnaryOperator UnaryOperator<BoundStatementBuilder>} can be added as the last
* parameter. It will be applied to the statement before execution. This allows you to customize
* certain aspects of the request (page size, timeout, etc) at runtime.
*
*
Return type
*
* The method can return:
*
*
* - {@code void}.
*
- a {@code boolean} or {@link Boolean}, which will be mapped to {@link
* ResultSet#wasApplied()}. This is intended for IF EXISTS queries:
*
* @Delete(ifExists = true)
* boolean deleteIfExists(Product product);
*
* - a {@link ResultSet}. This is intended for queries with custom IF clauses; when those
* queries are not applied, they return the actual values of the tested columns.
*
* @Delete(entityClass = Product.class, customIfClause = "description = :expectedDescription")
* ResultSet deleteIfDescriptionMatches(UUID productId, String expectedDescription);
* // if the condition fails, the result set will contain columns '[applied]' and 'description'
*
* - a {@link BoundStatement}. This is intended for queries where you will execute this
* statement later or in a batch.
*
* @Delete
* BoundStatement delete(Product product);
*
* - a {@link CompletionStage} or {@link CompletableFuture} of any of the above. The method will
* execute the query asynchronously. Note that for result sets, you need to switch to {@link
* AsyncResultSet}.
*
* @Delete
* CompletableFuture<Void> deleteAsync(Product product);
*
* @Delete(ifExists = true)
* CompletionStage<Boolean> deleteIfExistsAsync(Product product);
*
* @Delete(entityClass = Product.class, customIfClause = "description = :expectedDescription")
* CompletionStage<AsyncResultSet> deleteIfDescriptionMatchesAsync(UUID productId, String expectedDescription);
*
*
*
* Note that you can also return a boolean or result set for non-conditional queries, but there's no
* practical purpose for that since those queries always return {@code wasApplied = true} and an
* empty result set.
*
* Target keyspace and table
*
* If a keyspace was specified when creating the DAO (see {@link DaoFactory}), then the generated
* query targets that keyspace. Otherwise, it doesn't specify a keyspace, and will only work if the
* mapper was built from a {@link Session} that has a {@linkplain
* SessionBuilder#withKeyspace(CqlIdentifier) default keyspace} set.
*
* If a table was specified when creating the DAO, then the generated query targets that table.
* Otherwise, it uses the default table name for the entity (which is determined by the name of the
* entity class and the naming convention).
*/
@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface Delete {
/**
* A hint to indicate the entity class, for cases where it can't be determined from the method's
* signature.
*
*
This is only needed if the method receives the primary key components as arguments or uses a
* custom where clause:
*
*
* @Delete(entityClass = Product.class)
* void delete(UUID productId);
*
* @Delete(entityClass = Product.class, customWhereClause="product_id = :productId")
* void delete(UUID productId);
*
*
* Note that, for technical reasons, this is an array, but only one element is expected. If you
* specify more than one class, the mapper processor will generate a compile-time warning, and
* proceed with the first one.
*/
Class[] entityClass() default {};
/**
* A custom WHERE clause for the DELETE query.
*
* If this is not empty, it completely replaces the WHERE clause in the generated query. Note
* that the provided string must not contain the {@code WHERE} keyword and {@link
* #entityClass()} must be specified.
*
*
This clause can contain placeholders that will be bound with the method's parameters; see
* the top-level javadocs of this class for more explanations.
*
*
Also note that this can be used in conjunction with {@link #customIfClause()} or {@link
* #ifExists()}.
*/
String customWhereClause() default "";
/**
* Whether to append an IF EXISTS clause at the end of the generated DELETE query.
*
*
This is mutually exclusive with {@link #customIfClause()} (if both are set, the mapper
* processor will generate a compile-time error).
*/
boolean ifExists() default false;
/**
* A custom IF clause for the DELETE query.
*
*
This is mutually exclusive with {@link #ifExists()} (if both are set, the mapper processor
* will generate a compile-time error).
*
*
If this is not empty, it gets added to the generated query. Note that the provided string
* must not contain the {@code IF} keyword.
*
*
This clause can contain placeholders that will be bound with the method's parameters; see
* the top-level javadocs of this class for more explanations.
*/
String customIfClause() default "";
}