MyBatis-Plus 处理逻辑删除与查询的5种核心实现方法

# application.yml
mybatis-plus:
  global-config:
    db-config:
      logic-delete-field: deleted  # 全局逻辑删除字段名
      logic-delete-value: 1        # 逻辑已删除值（默认为1）
      logic-not-delete-value: 0    # 逻辑未删除值（默认为0）

import com.baomidou.mybatisplus.annotation.TableLogic;
import com.baomidou.mybatisplus.annotation.TableName;
@Data
@TableName("user")
public class User {
    private Long id;
    private String name;
    @TableLogic(value = "0", delval = "1")
    private Integer deleted;
}
@Data
@TableName("product")
public class Product {
    private Long id;
    private String productName;
    @TableLogic(value = "false", delval = "true")
    private Boolean isDeleted;
}

// 1. 查询时忽略逻辑删除条件
List<User> users = userMapper.selectList(
    Wrappers.<User>lambdaQuery()
        .apply("deleted = 1 or deleted = 0")  // 自定义条件覆盖自动添加的条件
);
// 2. 使用自定义SQL完全控制
@Select("SELECT * FROM user WHERE id = #{id}")
User selectByIdIgnoreLogic(@Param("id") Long id);
// 3. 链式调用中的特殊处理
userMapper.selectList(
    new QueryWrapper<User>()
        .eq("status", 1)
        .and(wrapper -> wrapper.eq("deleted", 0).or().isNull("deleted"))
);

// 1. 配置类中自定义逻辑删除处理器
@Configuration
public class MybatisPlusConfig {
    @Bean
    public ISqlInjector sqlInjector() {
        return new LogicSqlInjector() {
            @Override
            protected String getLogicDeleteSql(TableInfo tableInfo, boolean withWhere) {
                // 自定义逻辑删除SQL生成逻辑
                String logicDeleteField = tableInfo.getLogicDeleteField();
                return "UPDATE " + tableInfo.getTableName() + 
                       " SET " + logicDeleteField + " = #{et." + logicDeleteField + "}" +
                       (withWhere ? " WHERE " + tableInfo.getKeyColumn() + "=#{et." + tableInfo.getKeyProperty() + "}" : "");
            }
        };
    }
}
// 2. 使用@SqlParser注解控制过滤
@SqlParser(filter = true)  // 过滤逻辑删除数据
public List<User> selectActiveUsers();
@SqlParser(filter = false) // 不过滤逻辑删除数据
public List<User> selectAllUsers();

// 1. 多租户配置类
@Configuration
public class TenantConfig {
    @Bean
    public TenantLineHandler tenantLineHandler() {
        return new TenantLineHandler() {
            @Override
            public String getTenantIdColumn() {
                return "tenant_id";
            }
            @Override
            public Expression getTenantId() {
                return new LongValue(UserContext.getCurrentTenantId());
            }
            @Override
            public boolean ignoreTable(String tableName) {
                // 忽略不需要多租户的表
                return "system_config".equals(tableName);
            }
        };
    }
}
// 2. 实体类同时支持多租户和逻辑删除
@Data
@TableName("order")
public class Order {
    private Long id;
    private String orderNo;
    @TableField(fill = FieldFill.INSERT)  // 自动填充租户ID
    private Long tenantId;
    @TableLogic
    private Integer deleted;
}
// 3. 查询时自动添加租户和逻辑删除条件
List<Order> orders = orderMapper.selectList(
    Wrappers.<Order>lambdaQuery()
        .eq(Order::getStatus, 1)
        // 会自动添加：AND tenant_id = 当前租户ID AND deleted = 0
);

// 事务中处理逻辑删除
@Transactional
public void deleteUserWithRelatedData(Long userId) {
    // 删除用户
    userMapper.deleteById(userId);
    // 同时处理关联数据
    userRoleMapper.deleteByUserId(userId);
    // 记录操作日志
    logService.saveDeleteLog(userId);
}