com.datastax.driver.mapping.annotations.Computed 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.driver.mapping.annotations;
import com.datastax.driver.mapping.Mapper;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
/**
* Annotates a "computed" property, which gets filled from a CQL expression in the SELECT query used
* to retrieve an entity.
*
* Note that such properties are only filled by default mapper operations ({@link
* Mapper#get(Object...)}), they will be ignored in accessor queries and save operations.
*
*
As opposed to other mapper annotations, this one doesn't handle case sensitivity. If your
* expression contains case-sensitive names, you'll need to quote them explicitly:
*
*
* {@code @Computed("\"caseSensitiveFunction\"(v)")}
*
*/
@Target({ElementType.FIELD, ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
public @interface Computed {
/**
* The formula used to compute the property.
*
* This is a CQL expression like you would use directly in a query, for instance {@code
* "writetime(v)"}.
*
* @return the formula.
*/
String value();
}