paginated next button not working in asp.net core - asp.net-core

Question

I'm new to asp.net MVC core
trying to build a page where you choose multiple search options
I need a get and post actions for that, the results should be in a partial view that is paginated, the code works fine until I click next or previous, I lose the whole search result object cuz the model doesn't bind them back
[HttpGet]
public ViewResult SearchOutbox(DocumentSearchViewModel doc)
{
var documentSearchViewModel = PopulateDocumentSearchViewModel(doc);//this method fills the dropdowns
return View(documentSearchViewModel);
}
[HttpPost]
public async Task<IActionResult> SearchOutbox(DocumentSearchViewModel doc, int? page)
{
var documentSearchViewModel = PopulateDocumentSearchViewModel(doc);
if (ModelState.IsValid)
{
IQueryable<Document> documents = _documentRepository.SearchDocument(documentSearchViewModel);
documentSearchViewModel.Documents = await PaginatedList<Document>.CreateAsync(documents.AsNoTracking(), page ?? 1, 1);
return View("SearchOutbox",documentSearchViewModel);
}
return View();
}
partial view
....
<a asp-action="SearchOutbox"
asp-route-page="#(Model.PageIndex - 1)"
class="btn btn-default #prevDisabled">
Previous
</a>
<a asp-action="SearchOutbox"
asp-route-page="#(Model.PageIndex + 1)"
class="btn btn-default #nextDisabled">
Next
</a>
main view calling partial
<partial name="_ListDocument" model="#Model.Documents">

Answer 1

Before diving into the details, it is worth to mention that for pagination you can use GET only, no need to use POST.
Back yo your question; if the result set is based on some filters, you have to pass all those filters parameters along with the pagination link.
e.g. if you have a URL like below one you can survive by sending only page parameter to the relevant action:
http://example.com/products/?page=1
But whenever you add some filters to the URL, you have to include all of them in the paging buttons, e.g. in below URL you have to send all paramters after ? to the paging action so it can select the next page from the filtered results using the same filtering options:
http://example.com/products/?page=1&category=mobile&brand=xyz
You can add all parameters manually, or you can use a function that will read the query string values then only increase the page number and generate new URL. Below is a function that do the page number increase and replace it via regex:
Previous
Next
#{
string CreateUrl(int newPage)
{
var index = int.Parse(Request.QueryString["page"].ToString());
var input = Request.QueryString.Value;
var replacement = $"page={index + newPage}";
var pattern = #"page=\d+";
return System.Text.RegularExpressions.Regex.Replace(input, pattern, replacement);
}
}
There is some nuget packages that can handle advanced paging functionalities like LazZiya.TagHelpers, install from nuget :
Install-Package LazZiya.TagHelpers -Version 3.0.2
Add paging tag helper to _ViewImports :
#addTagHelper *, LazZiya.TagHelpers
Then use it where you need a paging control:
<paging
total-records="Model.TotalRecords"
page-no="Model.PageNo"
query-string-key-page-no="page"
query-string-value="#(Request.QueryString.Value)">
</paging>
Notice : in the latest preview version (v3.1.0-preview1) no need to add query-string-value so the tag helper will work like below:
<paging
total-records="Model.TotalRecords"
page-no="Model.PageNo"
query-string-key-page-no="page"
</paging>
See tutorial, live demo and docs