MybatisPlus查询小例子

例1：
@Override
public PageUtils queryBaseAttrPage(Map<String, Object> params, Long catelogId) {
    QueryWrapper<AttrEntity> queryWrapper = new QueryWrapper<>();
    if(catelogId != 0) {
        queryWrapper.eq("catelog_id", catelogId);
    }
    String key = (String) params.get("key");
    if(!StringUtils.isEmpty(key)) {
        queryWrapper.and((wrapper) -> {
            wrapper.eq("attr_id", key).or().like("attr_name", key);
        });
    }
    IPage<AttrEntity> page = this.page(
            new Query<AttrEntity>().getPage(params),
            queryWrapper
    );
    return new PageUtils(page);
}

例2：

@Override
public PageUtils queryBaseAttrPage(Map<String, Object> params, Long catelogId) {
    QueryWrapper<AttrEntity> queryWrapper = new QueryWrapper<>();
    if(catelogId != 0) {
        queryWrapper.eq("catelog_id", catelogId);
    }
    String key = (String) params.get("key");
    if(!StringUtils.isEmpty(key)) {
        queryWrapper.and((wrapper) -> {
            wrapper.eq("attr_id", key).or().like("attr_name", key);
        });
    }
    IPage<AttrEntity> page = this.page(
            new Query<AttrEntity>().getPage(params),
            queryWrapper
    );

    PageUtils pageUtils = new PageUtils(page);
    List<AttrEntity> records = page.getRecords();
    List<AttrRespVo> respVos = records.stream().map((attrEntity -> {
        AttrRespVo attrRespVo = new AttrRespVo();
        BeanUtils.copyProperties(attrEntity, attrRespVo);
        AttrAttrgroupRelationEntity attrId = relationDao.selectOne(new QueryWrapper<AttrAttrgroupRelationEntity>().eq("attr_id", attrEntity.getAttrId()));
        if (attrId != null) {
            AttrGroupEntity attrGroupEntity = attrGroupDao.selectById(attrId.getAttrGroupId());
            attrRespVo.setGroupName(attrGroupEntity.getAttrGroupName());
        }
        CategoryEntity categoryEntity = categoryDao.selectById(attrEntity.getCatelogId());
        if (categoryEntity != null) {
            attrRespVo.setCatelogName(categoryEntity.getName());
        }
        return attrRespVo;
    })).collect(Collectors.toList());
    pageUtils.setList(respVos);
    return pageUtils;
}

例3：

@Override
public PageUtils queryPageByCondition(Map<String, Object> params) {
    QueryWrapper<SpuInfoEntity> wrapper = new QueryWrapper<>();

    String key = (String) params.get("key");
    if(!StringUtils.isEmpty(key)) {
        wrapper.and((w) -> {
            w.eq("id", key).or().like("spu_name", key);
        });
    }
    String status = (String) params.get("status");
    if(!StringUtils.isEmpty(status)) {
        wrapper.eq("publish_status",status);
    }
    String brandId = (String) params.get("brandId");
    if(!StringUtils.isEmpty(brandId)) {
        wrapper.eq("brand_id", brandId);
    }
    String catelogId = (String) params.get("catelogId");
    if(!StringUtils.isEmpty(catelogId)) {
        wrapper.eq("catelog_id", catelogId);
    }

    IPage<SpuInfoEntity> page = this.page(
            new Query<SpuInfoEntity>().getPage(params),
            wrapper
    );

    return new PageUtils(page);
}