How to set new value to existing query string Blazor - asp.net-core

Question

I'm attempting to change a query string paramater without reloading the page. I have a DateTime Date value that I'm attempting to turn into a string and put into the url. Say, for the sake of this question that it is:
DateTime? Date = new DateTime(2020, 9, 4);
So, my url could begin looking like:
https://localhost:44346/Events?d=2020-10-18
and after I do whatever magic must be done, it ends up like:
https://localhost:44346/Events?d=2020-10-04
I have attempted using NavigationManager and QueryHelpers like the following, but I've had no luck:
QueryHelpers.AddQueryString(navManager.Uri, "d", Date?.ToString("yyyy-MM-dd"));

Answer 1

Please check out this demo
#page "/counter"
#using Microsoft.AspNetCore.WebUtilities
#using System.Web
#inject NavigationManager navManager
<button class="btn btn-primary" #onclick="ChangeUrl">Change url</button>
<br />
demonstrate lack of page reload
<br />
<button class="btn btn-primary" #onclick="AddItem">Add item</button>
#foreach (var item in list)
{
#item
}
#code {
private List<string> list = new List<string>()
{
"Test string"
};
private void AddItem()
{
var uri = navManager.ToAbsoluteUri(navManager.Uri);
if (QueryHelpers.ParseQuery(uri.Query).TryGetValue("d", out var param))
{
list.Add(param.First());
}
else
{
list.Add("d is empty");
}
}
DateTime dateCounter = DateTime.Today;
private void ChangeUrl()
{
dateCounter = dateCounter.AddDays(1);
string url = RemoveQueryStringByKey(navManager.Uri, "d");
var query = new Dictionary<string, string> { { "d", dateCounter.ToString("dd-MM-yyyy") } };
navManager.NavigateTo(QueryHelpers.AddQueryString(url, query));
}
public static string RemoveQueryStringByKey(string url, string key)
{
var uri = new Uri(url);
// this gets all the query string key value pairs as a collection
var newQueryString = HttpUtility.ParseQueryString(uri.Query);
// this removes the key if exists
newQueryString.Remove(key);
// this gets the page path from root without QueryString
string pagePathWithoutQueryString = uri.GetLeftPart(UriPartial.Path);
return newQueryString.Count > 0
? String.Format("{0}?{1}", pagePathWithoutQueryString, newQueryString)
: pagePathWithoutQueryString;
}
}