如何在web api中创建分页？ [英] How to create pagination in web api?

问题描述

我正在尝试创建一个查询字符串，它允许使用分页过滤所有结果。 （即api / test？name = frs& page = 2）



例如：

如果查询返回20条数据记录，我希望每个页面显示10行记录，因此如果我调用[api / test？name = frs& page = 1]，它将显示查询的前10条记录。

如果我查询[api / test？name = frs& page = 2]，那么页面现在会显示第二组10条记录。



目前，我已经尝试为页面过滤器编写一些代码行，但我仍然无法从查询字符串中获取所有记录（即api / test？name = frs& page = 1）。此查询返回总共20条记录，它只显示前10条，当我在页面过滤器中添加时 - > api / test？name = frs& page = 2，它仍然显示第一组10条记录，而不是显示第二组10条记录。

I am trying to create a query string, which allows all the results to be filtered using pagination. (i.e. api/test?name=frs&page=2)

for example:
if the query returns 20 records of data, i would like the each page to show 10 lines of records, hence if I call [api/test?name=frs&page=1], and it would show me first 10 records of the query.
if I query [api/test?name=frs&page=2], then the page would now show me second set of 10 records.

Currently, I have tried writing some lines of code for the page filter but I am still unable to get all the records from the querystring (i.e. api/test?name=frs&page=1). This query returns total number of 20 records and it only shows first 10 and when I add in the page filter --> api/test?name=frs&page=2, it still shows the first set of 10 records, instead of showing the second set of 10 records.

public HttpResponseMessage get([FromUri] Query query )
     {
            if (User.IsInRole("admin"))
         {
         int pageSize = 10;
         int page = 0;

     //code for getting data (i.e. name, tag etc)

             var totalCount = Data.Count();
             var totalPages = (int)Math.Ceiling((double)totalCount / pageSize);

             //var urlHelper = new UrlHelper(Request);
            // var prevLink = page > 0 ? urlHelper.Link("DefaultApi", new { page = page - 1 }) : "";
            // var nextLink = page < totalPages - 1 ? urlHelper.Link("DefaultApi", new { page = page + 1 }) : "";

             var pageValue = Request.RequestUri.ParseQueryString().Get("page");
             int currentPage;
             if (!int.TryParse(pageValue, out currentPage))
             {
                 currentPage = 0;
             }

             Data = Data.OrderByDescending(c => c.UploadDate);

             var data = Data.Skip(pageSize * page).Take(pageSize).ToList();

             if (!data.Any())
             {
                 var message = string.Format("No data found");
                 return Request.CreateErrorResponse(HttpStatusCode.NotFound, message);
             }

             //return Request.CreateResponse(HttpStatusCode.OK, data);
            // return Request.CreateResponse(HttpStatusCode.OK, new { totalCount, totalPages, prevLink, nextLink, data });
             return Request.CreateResponse(HttpStatusCode.OK, new { totalCount, totalPages, pageValue, data });
         }
            return Request.CreateErrorResponse(HttpStatusCode.NotFound, "Access Denied");
     }

请帮助。



我希望我已经清楚地澄清了分页问题，​​如果没有，请告诉我。谢谢你的回复

Please help.

I hope i have clarified the pagination issue clearly, if not, please do let me know. Thank you for your reply

推荐答案

看起来你在skip方法中使用了错误的变量。页面变量始终设置为0，从查询字符串获得的页面变量在prasing后命名为currentPage。想你忘了你创建了第一个变量。

It looks like you using the wrong variable in your skip method. The page variable is always set to 0 and the one you get from your query string is named currentPage after prasing. Think you forgot you created the first variable.

var data = Data.Skip(pageSize * page).Take(pageSize).ToList();

修复：

Fix:

var data = Data.Skip(pageSize * currentPage).Take(pageSize).ToList();

您还可以在TryPrase方法中将输出参数更改为page。无论哪种方式都有效。

You could also change the output parameter to page in your TryPrase method. Either way works.

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