org.springframework.data.jpa.repository.query.ExpressionBasedStringQuery Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of spring-data-jpa Show documentation
Show all versions of spring-data-jpa Show documentation
Spring Data module for JPA repositories.
/*
* Copyright 2013-2019 the original author or authors.
*
* 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 org.springframework.data.jpa.repository.query;
import java.util.regex.Pattern;
import org.springframework.data.repository.core.EntityMetadata;
import org.springframework.expression.Expression;
import org.springframework.expression.ParserContext;
import org.springframework.expression.spel.standard.SpelExpressionParser;
import org.springframework.expression.spel.support.StandardEvaluationContext;
import org.springframework.util.Assert;
/**
* Extension of {@link StringQuery} that evaluates the given query string as a SpEL template-expression.
*
* Currently the following template variables are available:
*
* - {@code #entityName} - the simple class name of the given entity
*
*
* @author Thomas Darimont
* @author Oliver Gierke
* @author Tom Hombergs
*/
class ExpressionBasedStringQuery extends StringQuery {
private static final String EXPRESSION_PARAMETER = "?#{";
private static final String QUOTED_EXPRESSION_PARAMETER = "?__HASH__{";
private static final Pattern EXPRESSION_PARAMETER_QUOTING = Pattern.compile(Pattern.quote(EXPRESSION_PARAMETER));
private static final Pattern EXPRESSION_PARAMETER_UNQUOTING = Pattern.compile(Pattern
.quote(QUOTED_EXPRESSION_PARAMETER));
private static final String ENTITY_NAME = "entityName";
private static final String ENTITY_NAME_VARIABLE = "#" + ENTITY_NAME;
private static final String ENTITY_NAME_VARIABLE_EXPRESSION = "#{" + ENTITY_NAME_VARIABLE + "}";
/**
* Creates a new {@link ExpressionBasedStringQuery} for the given query and {@link EntityMetadata}.
*
* @param query must not be {@literal null} or empty.
* @param metadata must not be {@literal null}.
* @param parser must not be {@literal null}.
*/
public ExpressionBasedStringQuery(String query, JpaEntityMetadata metadata, SpelExpressionParser parser) {
super(renderQueryIfExpressionOrReturnQuery(query, metadata, parser));
}
/**
* Creates an {@link ExpressionBasedStringQuery} from a given {@link DeclaredQuery}.
*
* @param query the original query. Must not be {@literal null}.
* @param metadata the {@link JpaEntityMetadata} for the given entity. Must not be {@literal null}.
* @param parser Parser for resolving SpEL expressions. Must not be {@literal null}.
* @return A query supporting SpEL expressions.
*/
static ExpressionBasedStringQuery from(DeclaredQuery query, JpaEntityMetadata metadata,
SpelExpressionParser parser) {
return new ExpressionBasedStringQuery(query.getQueryString(), metadata, parser);
}
/**
* @param query, the query expression potentially containing a SpEL expression. Must not be {@literal null}.}
* @param metadata the {@link JpaEntityMetadata} for the given entity. Must not be {@literal null}.
* @param parser Must not be {@literal null}.
* @return
*/
private static String renderQueryIfExpressionOrReturnQuery(String query, JpaEntityMetadata metadata,
SpelExpressionParser parser) {
Assert.notNull(query, "query must not be null!");
Assert.notNull(metadata, "metadata must not be null!");
Assert.notNull(parser, "parser must not be null!");
if (!containsExpression(query)) {
return query;
}
StandardEvaluationContext evalContext = new StandardEvaluationContext();
evalContext.setVariable(ENTITY_NAME, metadata.getEntityName());
query = potentiallyQuoteExpressionsParameter(query);
Expression expr = parser.parseExpression(query, ParserContext.TEMPLATE_EXPRESSION);
String result = expr.getValue(evalContext, String.class);
if (result == null) {
return query;
}
return potentiallyUnquoteParameterExpressions(result);
}
private static String potentiallyUnquoteParameterExpressions(String result) {
return EXPRESSION_PARAMETER_UNQUOTING.matcher(result).replaceAll(EXPRESSION_PARAMETER);
}
private static String potentiallyQuoteExpressionsParameter(String query) {
return EXPRESSION_PARAMETER_QUOTING.matcher(query).replaceAll(QUOTED_EXPRESSION_PARAMETER);
}
private static boolean containsExpression(String query) {
return query.contains(ENTITY_NAME_VARIABLE_EXPRESSION);
}
}