[我试图在由Blazor
生成的事件上更新我的js
页面。Js
与interop调用事件上的C#代码,我需要以某种方式在c#回调中调用this.StateHasChanged
:
JS
window.methods = {
timeout: null,
setTimeout: function () {
timeout = window.setInterval(async function () {
console.log("From js timeout occured ,sending to .net");
await DotNet.invokeMethodAsync('[assembly name]', "TimeoutCallback", Date.now().toString());
}, 2000);
},
clearTimeout: function () {
if (this.timeout == null || this.timeout == undefined) {
return;
}
console.log("Clearing timeout");
window.clearTimeout(timeout);
}
}
C#
@inherits StuffBase
@page "/test"
Current value: @val
<button onclick="@(async()=>await StartTimeout())">Start timeout </button>
<button onclick="@(async()=>await ClearTimeout())">Clear timeout</button>
public class StuffBase : BlazorComponent {
protected static string val { get; set; }
protected async Task StartTimeout() {
await JSMethods.SetTimeout();
}
[JSInvokable("TimeoutCallback")] //gets called by js on event !
public static async Task TimeoutCallback(string data) {
val = data;
Console.WriteLine("From callback ,received:" + data); //gets updated
await Task.Delay(1000);
//how can i call this.StateHasChanged
}
protected async Task ClearInterval() {
await JSMethods.ClearInterval();
}
}
Interop
public class JSMethods {
public static async Task SetTimeout() {
await JSRuntime.Current.InvokeAsync<string>("methods.setTimeout");
}
public static async Task ClearTimeout() {
await JSRuntime.Current.InvokeAsync<string>("methods.clearTimeout");
}
}
如您所见,首先我从c#
-> setTimeout
进行调用,该代码在js中将超时值与其处理程序附加在一起。发生的是,我设法从TimeoutCallback
中调用了js
,但是在console
中,我更新了我的值,因此我需要以某种方式通知UI
进行自我更新。
由于我从.NET
have(根据文档)被调用的所有js
方法都设为static
,我该如何实现?
那么如果它们是静态的呢?这是否意味着您不能调用StateHasChanged方法。只需在TimeoutCallback方法的末尾键入以下内容:StateHasChanged();
[无论如何,如果是这样,并且您无法从TimeoutCallback方法调用StateHasChanged方法,则可以从TimeoutCallback方法调用事件处理程序,如下所示:TimeoutCallbackLoaded?.Invoke(data);
然后从那里调用StateHasChanged();
编辑:好的,我现在注意到,您已经定义了一个名为JSMethods的类,它具有两个调用SetTimeout和ClearTimeout的方法。在这种情况下,更好的设计是在该类中还定义TimeoutCallback。毕竟相关,对吗?然后,如上所述定义事件处理程序,该事件处理程序将事件的发生通知订阅者(您的UI代码),并将从JSIterop返回的数据传递给该事件处理程序,然后在处理UI代码中事件的方法中,可以调用[C0 ]
我认为将C#实例传递给JS并让您的JS回调到该C#实例是一个更好的选择。
StuffBase.cs
StateHasChanged();
JS
public class StuffBase : ComponentBase
{
protected static string val { get; set; }
protected async Task StartTimeout()
{
await JSRuntime.Current.InvokeAsync<string>("methods.setTimeout", new DotNetObjectRef(this));
}
[JSInvokable("TimeoutCallback")] //gets called by js on event !
public async Task TimeoutCallback(string data)
{
val = data;
Console.WriteLine("From callback ,received:" + data); //gets updated
await Task.Delay(1000);
StateHasChanged();
}
protected async Task ClearTimeout()
{
await JSMethods.ClearTimeout();
}
}
由于用户@Isaac建议添加事件,并从其回调中调用window.methods = {
timeout: null,
setTimeout: function (stuffBaseInstance) {
timeout = window.setInterval(async function () {
console.log("From js timeout occured ,sending to .net");
await stuffBaseInstance.invokeMethodAsync('TimeoutCallback', Date.now().toString());
}, 2000);
},
clearTimeout: function () {
if (this.timeout == null || this.timeout == undefined) {
return;
}
console.log("Clearing timeout");
window.clearTimeout(timeout);
}
}
,我已解决了问题:
StateHasChanged
经过对以上答案的大量讨论后,我无法使它们在核心3.1和Blazor Web程序集中工作。对于客户端blazor,JSInvokable仅适用于静态方法。因此,我的解决方案是让index.html中的javascript单击剃刀页面中定义的隐藏按钮:
index.html
public class StuffBase : BlazorComponent {
protected static string val { get; set; }
protected delegate void OnTimeout(string data);
private static event OnTimeout OnTimeOutOccured;
protected override void OnInit() {
OnTimeOutOccured += x => {
this.StateHasChanged();
};
}
protected async Task StartTimeout() {
await JSMethods.SetTimeout();
}
[JSInvokable("TimeoutCallback")]
public static async Task TimeoutCallback(string data) {
val = data;
Console.WriteLine("From callback ,received:" + data);
await Task.Delay(1000);
OnTimeOutOccured?.Invoke(data);
}
protected async Task ClearTimeout() {
await JSMethods.ClearTimeout();
}
}
然后在JSInteropRazor中,添加一个隐藏按钮以触发非静态方法以触发状态已更改,或者就我而言,刷新剃刀页面中的数据。
JSInterop.razor
<script language="javascript">
window.resetjs = function () {
document.getElementById('jspromptbutton').click();
}
</script>
</head>
<body>
<button type="button" class="btn btn-primary"
onclick="resetjs()">
fire prompt
</button>
种类繁多,但我一直在努力,直到找到一个更好的解决方案。