MongoDB 逻辑删除

梦里梦外; 2024-04-03 11:41 77阅读 0赞

#### 文章目录 ####

*  场景
 *  方案
 *  注解
 *  实体类
 *  初始化
 *  重写删除方法
 *  查询拦截器
 *   *  jpa 过滤
     *  MongoRepository 过滤

## 场景 ##

MongoDB 默认的删除方式是物理删除，但很多时候我们的需求都是逻辑删除，即通过某个字段去判断是否删除，类似于 MyBatisPlus 的 @TableLogic 注解

## 方案 ##

1.  自定义逻辑删除注解 @SoftDelete
2.  把注解加到实体类字段 deleteFlag 上
3.  创建数据时，初始化 deleteFlag 等于 N
4.  重写删除方法，改成把 deleteFlag 置 Y
5.  监听查询，每个查询都添加 deleteFlag = N 的查询条件

## 注解 ##

逻辑删除注解 @SoftDelete

@Target(ElementType.FIELD)
    @Retention(RetentionPolicy.RUNTIME)
    public @interface SoftDelete {
        
    }

## 实体类 ##

公共字段实体 BaseDO，所有实体都将继承它

@Data
    @EqualsAndHashCode(callSuper = false)
    @Accessors(chain = true)
    public class BaseDO implements Serializable {
        
    
        private static final long serialVersionUID = 1L;
    
        @ApiModelProperty(value = "主键")
        @Mapping("id")
        @Id
        private Long id;
    
        @SoftDelete
        @ApiModelProperty(value = "逻辑删除标记")
        private String deleteFlag;
    }

## 初始化 ##

*  AbstractMongoEventListener：监听器
 *  onBeforeConvert：在 object 被MongoConverter转换为Document之前，在MongoTemplate insert，insertList和save操作中调用
 *  参考文章：[MongnDB 自动装配][MongnDB]

@Configuration
    public class MongoCommonFieldsEventListener extends AbstractMongoEventListener {
        
    
        @Autowired
        ICurrentUserProvider currentUserProvider;
    
        @Override
        public void onBeforeConvert(BeforeConvertEvent event) {
        
            Object source = event.getSource();
            if (source instanceof BaseDO) {
        
                BaseDO entity = BaseDO.class.cast(source);
                if (entity.getCreationDate() == null) {
        
    				entity.setDeleteFlag("N");
    			}
            }
        }
    }

## 重写删除方法 ##

默认的删除方法 deleteById，会物理删除数据

重写：更新 deleteFlag 字段为 Y

public void delete(Long id) {
        
    	TestPO po = new TestPO();
    	po.setId(id);
    	po.setDeleteFlag("Y");
    	mongoTemplate.save(testPO);
    }

## 查询拦截器 ##

### jpa 过滤 ###

**过滤传参**  
自定义查询器

*  效果：每个查询都添加 deleteFlag = N 的查询条件
 *  PartTreeMongoQuery：jpa 查询必经之路
 *  javaType：通过 entityInformation 获取实体类
 *  annotationFieldOne：获取 SoftDelete 注解的字段名
 *  query：添加查询条件

public class CusPartTreeMongoQuery extends PartTreeMongoQuery {
        
    
        public CusPartTreeMongoQuery(MongoQueryMethod method, MongoOperations mongoOperations, SpelExpressionParser expressionParser, QueryMethodEvaluationContextProvider evaluationContextProvider) {
        
            super(method, mongoOperations, expressionParser, evaluationContextProvider);
        }
    
        @Override
        protected Query createQuery(ConvertingParameterAccessor accessor) {
        
            Query query = super.createQuery(accessor);
            query.fields();
            MongoQueryMethod queryMethod = super.getQueryMethod();
            MongoEntityMetadata<?> entityInformation = queryMethod.getEntityInformation();
            Class<?> javaType = entityInformation.getJavaType();
            Optional<Field> annotationFieldOne = ReflectionUtil.getAnnotationFieldOne(javaType, SoftDelete.class);
            annotationFieldOne.ifPresent(field -> {
        
                try {
        
                    query.addCriteria(Criteria.where(field.getName()).is("N"));
                } catch (Exception ignored) {
         }
            });
            return query;
        }
    }

ReflectionUtil 反射工具类：根据注解获取字段名

public class ReflectionUtil {
        
    
        private ReflectionUtil(){
        }
    
        public static Collection<Field> getAnnotationField(Object object, Class<? extends Annotation> annotation){
        
            return getAnnotationField(object.getClass(),annotation);
        }
    
        public static Collection<Field> getAnnotationField(Class<?> clazz,Class<? extends Annotation> annotation){
        
            List<Field> result = new ArrayList<>();
            Collection<Field> allDeclaredFields = getDeclaredFields(clazz);
            for (Field declaredField : allDeclaredFields) {
        
                if (declaredField.isAnnotationPresent(annotation)){
        
                    result.add(declaredField);
                }
            }
            return result;
        }
    
        public static Optional<Field> getAnnotationFieldOne(Class<?> clazz, Class<? extends Annotation> annotation){
        
            Collection<Field> result = getAnnotationField(clazz, annotation);
            return result.stream().findFirst();
        }
        public static Optional<Field> getFieldsByFieldName(Class<?> sourceClass,String fieldName){
        
            Collection<Field> declaredFields = getDeclaredFields(sourceClass);
            return declaredFields.stream().filter(field -> field.getName().equals(fieldName)).findFirst();
        }
    
        public static Collection<Field> getDeclaredFields(Class<?> sourceClass) {
        
            ArrayList<Field> result = new ArrayList<>();
            while (sourceClass.getDeclaredFields().length != 0) {
        
                result.addAll(Arrays.asList(sourceClass.getDeclaredFields().clone()));
                sourceClass = sourceClass.getSuperclass();
            }
            return result;
        }
    }

**工厂类**  
CusMongoRepositoryFactory

自定义工厂类，因为默认工厂类不会加载自定义的查询器

重点是最后一行，创建自定义查询器：return new CusPartTreeMongoQuery

public class CusMongoRepositoryFactory extends MongoRepositoryFactory {
        
        private static final SpelExpressionParser EXPRESSION_PARSER = new SpelExpressionParser();
        private final MongoOperations operations;
        private final MappingContext<? extends MongoPersistentEntity<?>, MongoPersistentProperty> mappingContext;
        /**
         * Creates a new {@link MongoRepositoryFactory} with the given {@link MongoOperations}.
         *
         * @param mongoOperations must not be {@literal null}.
         */
        public CusMongoRepositoryFactory(MongoOperations mongoOperations) {
        
            super(mongoOperations);
            Assert.notNull(mongoOperations, "MongoOperations must not be null!");
    
            this.operations = mongoOperations;
            this.mappingContext = mongoOperations.getConverter().getMappingContext();
    
        }
    
        @Override
        protected Optional<QueryLookupStrategy> getQueryLookupStrategy(QueryLookupStrategy.Key key, QueryMethodEvaluationContextProvider evaluationContextProvider) {
        
            return Optional.of(new CusMongoRepositoryFactory.MongoQueryLookupStrategy(operations, evaluationContextProvider, mappingContext));
        }
    
        /**
         * {@link QueryLookupStrategy} to create instances.
         *
         * @author Oliver Gierke
         * @author Thomas Darimont
         */
        private static class MongoQueryLookupStrategy implements QueryLookupStrategy {
        
    
            private final MongoOperations operations;
            private final QueryMethodEvaluationContextProvider evaluationContextProvider;
            MappingContext<? extends MongoPersistentEntity<?>, MongoPersistentProperty> mappingContext;
    
            public MongoQueryLookupStrategy(MongoOperations operations,
                                            QueryMethodEvaluationContextProvider evaluationContextProvider,
                                            MappingContext<? extends MongoPersistentEntity<?>, MongoPersistentProperty> mappingContext) {
        
    
                this.operations = operations;
                this.evaluationContextProvider = evaluationContextProvider;
                this.mappingContext = mappingContext;
            }
    
            /*
             * (non-Javadoc)
             * @see org.springframework.data.repository.query.QueryLookupStrategy#resolveQuery(java.lang.reflect.Method, org.springframework.data.repository.core.RepositoryMetadata, org.springframework.data.projection.ProjectionFactory, org.springframework.data.repository.core.NamedQueries)
             */
            @Override
            public RepositoryQuery resolveQuery(Method method, RepositoryMetadata metadata, ProjectionFactory factory,
                                                NamedQueries namedQueries) {
        
    
                MongoQueryMethod queryMethod = new MongoQueryMethod(method, metadata, factory, mappingContext);
                String namedQueryName = queryMethod.getNamedQueryName();
    
                if (namedQueries.hasQuery(namedQueryName)) {
        
                    String namedQuery = namedQueries.getQuery(namedQueryName);
                    return new StringBasedMongoQuery(namedQuery, queryMethod, operations, EXPRESSION_PARSER,
                            evaluationContextProvider);
                } else if (queryMethod.hasAnnotatedAggregation()) {
        
                    return new StringBasedAggregation(queryMethod, operations, EXPRESSION_PARSER, evaluationContextProvider);
                } else if (queryMethod.hasAnnotatedQuery()) {
        
                    return new StringBasedMongoQuery(queryMethod, operations, EXPRESSION_PARSER, evaluationContextProvider);
                } else {
        
                    return new CusPartTreeMongoQuery(queryMethod, operations, EXPRESSION_PARSER, evaluationContextProvider);
                }
            }
        }
    }

CusMongoRepositoryFactoryBean

public class CusMongoRepositoryFactoryBean <T extends Repository<S, ID>, S, ID extends Serializable> extends MongoRepositoryFactoryBean<T, S, ID> {
        
    
        public CusMongoRepositoryFactoryBean(Class<? extends T> repositoryInterface) {
        
            super(repositoryInterface);
        }
    
        @Override
        protected RepositoryFactorySupport getFactoryInstance(MongoOperations operations) {
        
            return new CusMongoRepositoryFactory(operations);
        }
    }

在启动类加载装配

@SpringBootApplication
    @EnableMongoRepositories(repositoryFactoryBeanClass = CusMongoRepositoryFactoryBean.class)
    public class Application {
        
    
        public static void main(String[] args) {
        
            SpringApplication.run(Application .class, args);
        }
    
    }

### MongoRepository 过滤 ###

接口继承 PagingAndSortingRepository 和 QueryByExampleExecutor

@NoRepositoryBean
    public interface CusMongoRepository<T, ID> extends PagingAndSortingRepository<T, ID>, QueryByExampleExecutor<T> {
        
    	...
    }

实现类 CusMongoRepositoryImpl

查询方法添加查询条件，以 findAll 做例子

public class CusMongoRepositoryImpl<T, ID> implements CusMongoRepository<T, ID> {
        
        private static final String SOFT_DELETION_KEY = "deleteFlag";
        private static final Object DELETE_TRUE = "Y";
        private static final Object DELETE_FALSE = "N";
        private final MongoOperations mongoOperations;
        private final MongoEntityInformation<T, ID> entityInformation;
    
        public CusMongoRepositoryImpl(
                MongoEntityInformation<T, ID> metadata, MongoOperations mongoOperations) {
        
            Assert.notNull(metadata, "MongoEntityInformation must not be null!");
            Assert.notNull(mongoOperations, "MongoOperations must not be null!");
            this.entityInformation = metadata;
            this.mongoOperations = mongoOperations;
        }
    
        @Override
        public List<T> findAll(@Nullable Query query) {
        
            if (query == null) {
        
                return Collections.emptyList();
            }
            query.addCriteria(where(SOFT_DELETION_KEY).is(DELETE_FALSE));
            return mongoOperations.find(
                    query, entityInformation.getJavaType(), entityInformation.getCollectionName());
        }
    }

在启动类加载装配

@SpringBootApplication
    @EnableMongoRepositories(repositoryFactoryBeanClass = CusMongoRepositoryFactoryBean.class,repositoryBaseClass = CusMongoRepositoryImpl.class)
    public class Application {
        
        public static void main(String[] args) {
        
            SpringApplication.run(Application .class, args);
        }
    }

[MongnDB]: https://blog.csdn.net/weixin_42555971/article/details/127262948