初始化 Blazor 组件中的对象
Initialize objects in Blazor component
使用这个 Blazor 组件:
@page "/counter"
<h1>Counter</h1>
<p>Current count: @_a.CurrentCount</p>
<button class="btn btn-primary" onclick="@_b.IncrementCount">Click me</button>
@functions {
private readonly ClassA _a = new ClassA();
private readonly ClassB _b = new ClassB(_a);
class ClassA
{
public int CurrentCount { get; set; }
}
class ClassB
{
private readonly ClassA _classA;
public ClassB(ClassA classA)
{
_classA = classA;
}
public void IncrementCount() => _classA.CurrentCount++;
}
}
我收到这个错误:
Error CS0236 A field initializer cannot reference the non-static field, method, or property '__Counter._a'
这个帖子解释了如何在标准 class:
中解决这个错误
Why can't you use 'this' in member initializers?
但是为此,它需要一个构造函数。
是否可以在 Blazor 组件中添加构造函数?
如何解决这个错误?
要保持 类 只读,您应该移动到 "code-behind"。然后你可以在构造函数上实例化 类:
@page "/counter"
@inherits CounterBase
<h1>Counter</h1>
<p>Current count: @_a.CurrentCount ...
CounterBase.cs
using Microsoft.AspNetCore.Blazor.Components;
namespace YourApp.Pages
{
public class ClassA
{
public int CurrentCount { get; set; }
}
public class ClassB
{
private readonly ClassA _classA;
public ClassB(ClassA classA)
{
_classA = classA;
}
public void IncrementCount() => _classA.CurrentCount++;
}
public class CounterBase : BlazorComponent
{
protected readonly ClassA _a;
protected readonly ClassB _b;
//constructor
public CounterBase()
{
_a = new ClassA();
_b = new ClassB(_a);
}
...
使用这个 Blazor 组件:
@page "/counter"
<h1>Counter</h1>
<p>Current count: @_a.CurrentCount</p>
<button class="btn btn-primary" onclick="@_b.IncrementCount">Click me</button>
@functions {
private readonly ClassA _a = new ClassA();
private readonly ClassB _b = new ClassB(_a);
class ClassA
{
public int CurrentCount { get; set; }
}
class ClassB
{
private readonly ClassA _classA;
public ClassB(ClassA classA)
{
_classA = classA;
}
public void IncrementCount() => _classA.CurrentCount++;
}
}
我收到这个错误:
Error CS0236 A field initializer cannot reference the non-static field, method, or property '__Counter._a'
这个帖子解释了如何在标准 class:
中解决这个错误Why can't you use 'this' in member initializers?
但是为此,它需要一个构造函数。
是否可以在 Blazor 组件中添加构造函数?
如何解决这个错误?
要保持 类 只读,您应该移动到 "code-behind"。然后你可以在构造函数上实例化 类:
@page "/counter"
@inherits CounterBase
<h1>Counter</h1>
<p>Current count: @_a.CurrentCount ...
CounterBase.cs
using Microsoft.AspNetCore.Blazor.Components;
namespace YourApp.Pages
{
public class ClassA
{
public int CurrentCount { get; set; }
}
public class ClassB
{
private readonly ClassA _classA;
public ClassB(ClassA classA)
{
_classA = classA;
}
public void IncrementCount() => _classA.CurrentCount++;
}
public class CounterBase : BlazorComponent
{
protected readonly ClassA _a;
protected readonly ClassB _b;
//constructor
public CounterBase()
{
_a = new ClassA();
_b = new ClassB(_a);
}
...