//创建分页的url
private string CreateArticleUrl(ArticlePrameters articlePrameters, PaginationUrlType paginationUrlType)
{
switch (paginationUrlType)
{
case PaginationUrlType.PreviousPage:
var CurrentPrameter = new ArticlePrameters
{
PageIndex = articlePrameters.PageIndex - 1,
PageSize = articlePrameters.PageSize,
OrderBy = articlePrameters.OrderBy,
Fields = articlePrameters.Fields
};
return(Url.Link("GetArticles", CurrentPrameter));
case PaginationUrlType.NextPage:
var NextPrameter = new ArticlePrameters
{
PageIndex = articlePrameters.PageIndex + 1,
PageSize = articlePrameters.PageSize,
OrderBy = articlePrameters.OrderBy,
Fields = articlePrameters.Fields
};
return(Url.Link("GetArticles", NextPrameter));
default:
var PreviousPrameter = new ArticlePrameters
{
PageIndex = articlePrameters.PageIndex,
PageSize = articlePrameters.PageSize,
OrderBy = articlePrameters.OrderBy,
Fields = articlePrameters.Fields
};
return(Url.Link("GetArticles", PreviousPrameter));
}
}
public async Task <IActionResult> Get(ArticlePrameters articlePrameters)
{
//验证排序字符串
if (!PropertyMappingContainer.ValidateMappingExistsFor <ArticleViewModel, Article>(articlePrameters.OrderBy))
{
return(BadRequest("排序的属性不存在！"));
}
//验证资源塑形字符串
if (!TypeHelper.TypeHasProperties <ArticleViewModel>(articlePrameters.Fields))
{
return(BadRequest("请求的属性不存在!"));
}
var ArticlesList = await Repository.GetAllArticleAsync(articlePrameters);
//将Article映射到ArticleModel
var ArticlesResource = Mapper.Map <IEnumerable <Article>, IEnumerable <ArticleViewModel> >(ArticlesList);
//根据fields进行资源塑形
var ArticlesAfterShaping = ArticlesResource.ToDynamicIEnumerable(articlePrameters.Fields);
//为每一个资源添加links属性
ArticlesAfterShaping = ArticlesAfterShaping.Select(x =>
{
x.TryAdd("links", CreateHateoasLinks((int)x.Where(y => y.Key == "Id").FirstOrDefault().Value, articlePrameters.Fields));
return(x);
});
//新建匿名类存放翻页元数据
var page = new
{
ArticlesList.PageSize,
ArticlesList.PageIndex,
ArticlesList.TotalItemsCount,
ArticlesList.PageCount
};
//为资源创建前后页链接
var links = CreateHateoasLinksForPages(articlePrameters, ArticlesList.HasNext, ArticlesList.HasPrevious);
var reslut = new
{
links,
value = ArticlesAfterShaping
};
//将page类转化为Json，并写入HTTP请求头中
Response.Headers.Add("Pagination", JsonConvert.SerializeObject(page, new JsonSerializerSettings {
ContractResolver = new CamelCasePropertyNamesContractResolver() //将变量首字母改为小写
}));
return(Ok(reslut));
}
//创建页面的links
public IEnumerable <LinkViewModel> CreateHateoasLinksForPages(ArticlePrameters articlePrameters, bool hasNextPage, bool hasLastPage)
{
var links = new List <LinkViewModel>();
//添加selfLink
links.Add(new LinkViewModel(CreateArticleUrl(articlePrameters, PaginationUrlType.CurrentPage), "self", "Get"));
//判断是否有前一页/后一页 并加入links
if (hasNextPage)
{
links.Add(new LinkViewModel(CreateArticleUrl(articlePrameters, PaginationUrlType.NextPage), "nextPage", "Get"));
}
if (hasLastPage)
{
links.Add(new LinkViewModel(CreateArticleUrl(articlePrameters, PaginationUrlType.PreviousPage), "lastPage", "Get"));
}
return(links);
}
//查找所有的博客
public async Task <PaginatedList <Article> > GetAllArticleAsync(ArticlePrameters articlePrameters)
{
var result = MyDbContext.Articles.AsQueryable();
//执行过滤操作
if (!string.IsNullOrEmpty(articlePrameters.Title))//标题
{
result = result.Where(x => x.Title.ToLowerInvariant() == articlePrameters.Title.ToLowerInvariant());
}
if (!string.IsNullOrEmpty(articlePrameters.Auther))//作者
{
result = result.Where(x => x.Auther.ToLowerInvariant() == articlePrameters.Auther.ToLowerInvariant());
}
if (articlePrameters.AfterTime != null)//在某个时间之后
{
result = result.Where(x => x.Date.CompareTo(articlePrameters.AfterTime) >= 0);
}
if (articlePrameters.BeforeTime != null)//在某个时间之前
{
result = result.Where(x => x.Date.CompareTo(articlePrameters.BeforeTime) <= 0);
}
//执行模糊查询操作
if (!string.IsNullOrEmpty(articlePrameters.Contain))//标题包含
{
result = result.Where(x => x.Title.ToLowerInvariant().Contains(articlePrameters.Contain.ToLowerInvariant()));
}
//根据排序选项排序
result = result.ApplySort(articlePrameters.OrderBy, PropertyMappingContainer.Resolve <ArticleViewModel, Article>());
//计算文章数量
var count = await result.CountAsync();
//执行分页操作
var data = await result.Skip(articlePrameters.PageSize *articlePrameters.PageIndex).Take(articlePrameters.PageSize).ToListAsync();
return(new PaginatedList <Article>(articlePrameters.PageSize, articlePrameters.PageIndex, count, data));
}
