C# Blazor-比较上一个状态和下一个状态
我有一个Blazor中的学生表,它来自一个api,我还收到一个推送数据来更新学生信息,这基本上是数据库更改后的分数,推送工作正常,分数正在更新,但我还想将表中已更新字段的背景颜色更改为红色,仅td标记几秒钟,我的代码如下:C# Blazor-比较上一个状态和下一个状态,c#,signalr,blazor,blazor-server-side,C#,Signalr,Blazor,Blazor Server Side,我有一个Blazor中的学生表,它来自一个api,我还收到一个推送数据来更新学生信息,这基本上是数据库更改后的分数,推送工作正常,分数正在更新,但我还想将表中已更新字段的背景颜色更改为红色,仅td标记几秒钟,我的代码如下: @foreach(var student in SS.GetStudents()){ <tr> <td> student.name </> <td> student.sectio
@foreach(var student in SS.GetStudents()){
<tr>
<td> student.name </>
<td> student.section </>
// trying to compare between the previous and next state
var stud = SS.GetStuentsCopy().SingleOrDefault(s =>s.Id == student.Id);
var color = "";
if(stud.score != student.score){
color = red;
}
<td class="@color"> student.score </>
</tr>
}
@code{
[Inject]
public StudentsStates SS { get; set;}
public StudentsResponse Students { get; set; }
protected override async Task OnInitializedAsync()
{
// Subscribe to the StateChanged EventHandler
SS.StateChanged +=
SSAdvancedStateChanged;
Students = await Service.GetStudents();
// update the students and the copy together
SS.UpdateStudents(Students)
SS.UpdateStudentsCopy(Students)
//upon receiving students updated score
hubConnection = new HubConnectionBuilder()
.WithUrl(NavigationManager.ToAbsoluteUri("/studhub"))
.Build();
hubConnection.On<StudentsResponse>("ReceiveMessage", s =>
{
// update the students after 3 sec update the copy
SS.UpdateStudents(s);
//Here the state is not being updated
// unless there is a new push
// or the issue might be in rendering
// FYI without the sleep also I can see the changes in the color
System.Threading.Thread.Sleep(3000);
SS.UpdateStudentsCopy(s);
}
}}
正如我上面所说的,一切正常,除了在一秒钟内有多次推送,第一次推送的学生分数的背景颜色变化太快,有时你甚至不会注意到它,因为推送的数据和状态正在更新,我想要的是在不影响下一次推送的学生分数的情况下减慢背景颜色,或者如果有更好的方法来解决这个问题,我们非常感谢您的回答。我建议为学生行创建一个组件,如下所示:
@foreach(var student in SS.GetStudents())
{
<StudentRow Student={student} />
}
@foreach(SS.GetStudents()中的var student)
{
}
然后在StudentRow组件中,您可以创建一个新的私有student变量,在延迟3秒后更新该变量,并在那里进行比较,而不是将ID保存在列表或其他副本中:
学生剃须刀
<tr>
<td> Student.name </>
<td> Student.section </>
var color = "";
if(StudentCopy.score != Student.score){
color = red;
}
<td class="@color"> student.score </>
</tr>
@code{
public StudentResponse StudentCopy { get; set; }
[Parameter]
public StudentResponse Student { get; set; }
protected override async Task OnParametersSetAsync()
{
await Task.Delay(3000);
StudentCopy = Student;
}
}
学生姓名
学生部
var color=“”;
if(StudentCopy.score!=Student.score){
颜色=红色;
}
学生成绩
@代码{
公共学生响应学生副本{get;set;}
[参数]
公共学生响应学生{get;set;}
受保护的重写异步任务OnParametersSetAsync()
{
等待任务。延迟(3000);
StudentCopy=学生;
}
}
OnParametersSetAsync方法,当组件从渲染树中的父组件接收到参数,并且传入的值已分配给属性时调用
<tr>
<td> Student.name </>
<td> Student.section </>
var color = "";
if(StudentCopy.score != Student.score){
color = red;
}
<td class="@color"> student.score </>
</tr>
@code{
public StudentResponse StudentCopy { get; set; }
[Parameter]
public StudentResponse Student { get; set; }
protected override async Task OnParametersSetAsync()
{
await Task.Delay(3000);
StudentCopy = Student;
}
}