[英]Get current URL in a Blazor component
我需要知道當前頁面的 URL 以檢查是否必須對元素應用某種樣式。 下面的代碼是一個例子。
@using Microsoft.AspNetCore.Blazor.Services
@inject IUriHelper UriHelper
@implements IDisposable
<h1>@url</h1>
<nav>
<div class="nav-wrapper">
<a href="#" class="brand-logo">Blazor</a>
<ul id="nav-mobile" class="right hide-on-med-and-down">
<li>
<NavLink href="/" Match=NavLinkMatch.All>
Home
</NavLink>
</li>
<li>
<NavLink href="/counter">
Counter
</NavLink>
</li>
<li>
<NavLink href="/fetchdata">
Fetch data
</NavLink>
</li>
</ul>
</div>
</nav>
@functions {
private string url = string.Empty;
protected override void OnInit()
{
url = UriHelper.GetAbsoluteUri();
UriHelper.OnLocationChanged += OnLocationChanged;
}
private void OnLocationChanged(object sender, LocationChangedEventArgs e)
{
url = newUriAbsolute;
}
public void Dispose()
{
UriHelper.OnLocationChanged -= OnLocationChanged;
}
}
我使用了與 Blazor 存儲庫中的 NavLink 組件相同的方法,但它不起作用。 有任何想法嗎?。
使用NavigationManager
類中的Uri
屬性。
在.razor
頁面上使用之前從注入中獲取它:
@inject NavigationManager MyNavigationManager
如果您更喜歡“代碼隱藏”體驗,或者像這樣在.cs
文件中:
using Microsoft.AspNetCore.Components;
...
[Inject]
public NavigationManager MyNavigationManager {get; set;}
@page "/navigate"
@inject NavigationManager MyNavigationManager
<h1>Current URL</h1>
<p>@(MyNavigationManager.Uri)</p>
有關導航(NavigateTo、BaseUri、ToAbsoluteUri、ToBaseRelativePath、...)的更多信息,請參見: URI 和導航狀態助手
MyNavigationManager.Uri
#> https://localhost:5001/counter/3?q=hi
MyNavigationManager.BaseUri
#> https://localhost:5001/
MyNavigationManager.NavigateTo("http://new location")
#> Navigates to new location
MyNavigationManager.LocationChanged
#> An event that fires when the navigation location has changed.
MyNavigationManager.ToAbsoluteUri("pepe")
#> https://localhost:5001/pepe
MyNavigationManager.ToBaseRelativePath(MyNavigationManager.Uri)
#> counter/3?q=hi
Helper: AddQueryParm( "q2", "bye" ) // (*1)
#> https://localhost:5001/counter/3?q=hi&q2=bye
Helper: GetQueryParm( "q" )
#> hi
(*1)
Net6 引入了GetUriWithQueryParameter
。 更多信息: 從 Blazor 操作查詢字符串
助手代碼:
@code {
[Parameter]
public string Id { get; set; }
// Blazor: add parm to URL
string AddQueryParm(string parmName, string parmValue)
{
var uriBuilder = new UriBuilder(MyNavigationManager.Uri);
var q = System.Web.HttpUtility.ParseQueryString(uriBuilder.Query);
q[parmName] = parmValue;
uriBuilder.Query = q.ToString();
var newUrl = uriBuilder.ToString();
return newUrl;
}
// Blazor: get query parm from the URL
string GetQueryParm(string parmName)
{
var uriBuilder = new UriBuilder(MyNavigationManager.Uri);
var q = System.Web.HttpUtility.ParseQueryString(uriBuilder.Query);
return q[parmName] ?? "";
}
}
首先,將NavigationManager
注入到需要獲取當前 URL 的組件中,如下所示:
@inject NavigationManager NavManager
現在使用以下行獲取當前 URL:
string Url = NavManager.Uri.ToString();
連接到頁面或組件中的OnLocationChanged
事件是沒有用的,因為它們是按需加載和處置的。
您應該在 app.cshtml 中注冊此事件,因為它不會被釋放。
您應該聽 IUriHelper 的 LocationChange,它會觸發函數執行您想要的操作,例如:
@using Microsoft.AspNetCore.Blazor.Components
@using Microsoft.Extensions.Logging
@inject Microsoft.AspNetCore.Blazor.Services.IUriHelper UriHelper
@inject ILogger<NavItem> logger
<li class="m-menu__item @(Active ? "m-menu__item--active" : "")">
<a href=@Url class="m-menu__link ">
<span class="m-menu__item-here"></span>
<i class="m-menu__link-icon @Icon"></i>
<span class="m-menu__link-text">@Text</span>
</a>
</li>
@functions {
protected override void OnInit()
{
UriHelper.OnLocationChanged += OnLocationChanges;
}
[Parameter]
private string Url { get; set; }
[Parameter]
private string Icon { get; set; }
[Parameter]
private string Text { get; set; }
private bool Active = false;
private void OnLocationChanges(object sender, string newLocation)
{
bool active = newLocation.Contains(Url);
if(active != Active) //Only re-render the components that need it
{
Active = active;
StateHasChanged();
logger.LogInformation("Location Change To:" + newLocation);
}
}
}
在我的情況下,我只需要頁面的 Uri 而不是基本 Uri。
我將所有代碼保存在 razor.cs 文件中,因此我從代碼隱藏中注入 NavigationManager,如下所示:
[Inject] public NavigationManager Navigation { get; set; }
Navigation.Uri 輸出:https://localhost:5001/nail-square-singel-shear-timber-timber
因此,要獲取頁面 Uri,只需執行以下操作:
Navigation.Uri.Replace(Navigation.BaseUri,"")
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