c# - 未找到类型的合适构造函数( View 组件)

Question

查看组件:

public class WidgetViewComponent : ViewComponent
{
    private readonly IWidgetService _WidgetService;

    private WidgetViewComponent(IWidgetService widgetService)
    {
        _WidgetService = widgetService;
    }

    public async Task<IViewComponentResult> InvokeAsync(int widgetId)
    {
        var widget = await _WidgetService.GetWidgetById(widgetId);
        return View(widget);
    }
}

在 View ~/Views/Employees/Details.cshtml

@await Component.InvokeAsync("Widget", new { WidgetId = Model.WidgetId } )

View 组件位于~Views/Shared/Components/Widget/Default.cshtml

我收到的错误如下:

InvalidOperationException: A suitable constructor for type 'MyApp.ViewComponents.WidgetViewComponent' could not be located. Ensure the type is concrete and services are registered for all parameters of a public constructor.

Answer 1

问题是你的构造函数是私有(private)的:

private WidgetViewComponent(IWidgetService widgetService)
{
    _WidgetService = widgetService;
}

它应该是公开的，否则 DI 无法访问它:

public WidgetViewComponent(IWidgetService widgetService)
{
    _WidgetService = widgetService;
}