Rotativa值不能为空.参数名称:上下文 [英] Rotativa Value cannot be null. Parameter name: context

问题描述

我正在尝试使用Rotativa生成PDF并返回字节，但是出现错误:

值不能为null.参数名称:context

这是我的代码:

public string getReportsPDF(string community, string procedure)
{
    SiteSuperReportsController controller = new SiteSuperReportsController();

    string value = "";
    byte[] pdfBytes = new byte[] { };

    if (procedure == "GetProductionTasks")
    {
        var actionPDF = new Rotativa.ActionAsPdf("RedBluePDF", new { community = community, procedure = procedure })
        {
            PageSize = Size.A4,
            PageOrientation = Rotativa.Options.Orientation.Landscape,
            PageMargins = { Left = 1, Right = 1 }
        };
        try
        {
            pdfBytes = actionPDF.BuildFile(controller.ControllerContext);
            value = "Works";
        }
        catch(Exception e)
        {
            value = e.Message.ToString();
        }
    }
    return value;
}

返回的值为Value不能为空.参数名称:context

我在做什么错了?

解决方案

一种选择是将对BuildFile的调用移动到控制器的操作方法中，其中控制器上下文可用作称为ControllerContext的属性./p>

如果您需要像示例中那样手动创建控制器，则必须自己创建上下文. Derek Comartin在他的博客文章在控制台应用程序中使用Razor(在ASP外部)中显示.NET Core MVC)如何针对ASP.Core 2项目执行此操作.对于您的情况，请尝试更改

pdfBytes = actionPDF.BuildFile(controller.ControllerContext);

到

pdfBytes = actionPDF.BuildFile(CreateDummyControllerContext("SiteSuperReports"));

使用以下方法:

    private ControllerContext CreateDummyControllerContext(string controllerName)
    {
        var context = new ControllerContext
        {
            HttpContext = new DefaultHttpContext
            {
                RequestServices = GetServiceProvider()
            },
            RouteData = new RouteData
            {
                Values = {{"controller", controllerName}}
            },
            ActionDescriptor = new Microsoft.AspNetCore.Mvc.Controllers.ControllerActionDescriptor
            {
                RouteValues = new Dictionary<string, string>(),
            }
        };

        return context;
    }

    // see https://codeopinion.com/using-razor-in-a-console-application/
    private ServiceProvider GetServiceProvider()
    {
        var services = new ServiceCollection();
        services.AddSingleton(PlatformServices.Default.Application);
        var environment = new HostingEnvironment
        {
            ApplicationName = Assembly.GetEntryAssembly().GetName().Name
        };
        services.AddSingleton<IHostingEnvironment>(environment);
        services.Configure<RazorViewEngineOptions>(options =>
        {
            options.FileProviders.Clear();
            options.FileProviders.Add(new PhysicalFileProvider(Directory.GetCurrentDirectory()));
        });
        services.AddSingleton<ObjectPoolProvider, DefaultObjectPoolProvider>();
        services.AddSingleton<DiagnosticSource>(new DiagnosticListener("Microsoft.AspNetCore"));

        services.AddLogging();
        services.AddMvc();

        return services.BuildServiceProvider();
    }

您可能需要添加Microsoft.Extensions.PlatformAbstractions程序包.

I am trying to use Rotativa to Generate a PDF and return the bytes, however I am getting the error:

Value cannot be null. Parameter name: context

Here is my code:

public string getReportsPDF(string community, string procedure)
{
    SiteSuperReportsController controller = new SiteSuperReportsController();

    string value = "";
    byte[] pdfBytes = new byte[] { };

    if (procedure == "GetProductionTasks")
    {
        var actionPDF = new Rotativa.ActionAsPdf("RedBluePDF", new { community = community, procedure = procedure })
        {
            PageSize = Size.A4,
            PageOrientation = Rotativa.Options.Orientation.Landscape,
            PageMargins = { Left = 1, Right = 1 }
        };
        try
        {
            pdfBytes = actionPDF.BuildFile(controller.ControllerContext);
            value = "Works";
        }
        catch(Exception e)
        {
            value = e.Message.ToString();
        }
    }
    return value;
}

The value returned is Value cannot be null. Parameter name: context

What am I doing wrong?

解决方案

One option is to move the call to BuildFile into an action method of a controller, where the controller context is available as property called ControllerContext.

If you need to create your controller manually like in your example, you will have to create the context yourself. Derek Comartin shows in his blog post Using Razor in a Console Application (outside of ASP.NET Core MVC) how to do this for an ASP.Core 2 project. For your scenario, try changing the

pdfBytes = actionPDF.BuildFile(controller.ControllerContext);

to

pdfBytes = actionPDF.BuildFile(CreateDummyControllerContext("SiteSuperReports"));

using the following methods:

    private ControllerContext CreateDummyControllerContext(string controllerName)
    {
        var context = new ControllerContext
        {
            HttpContext = new DefaultHttpContext
            {
                RequestServices = GetServiceProvider()
            },
            RouteData = new RouteData
            {
                Values = {{"controller", controllerName}}
            },
            ActionDescriptor = new Microsoft.AspNetCore.Mvc.Controllers.ControllerActionDescriptor
            {
                RouteValues = new Dictionary<string, string>(),
            }
        };

        return context;
    }

    // see https://codeopinion.com/using-razor-in-a-console-application/
    private ServiceProvider GetServiceProvider()
    {
        var services = new ServiceCollection();
        services.AddSingleton(PlatformServices.Default.Application);
        var environment = new HostingEnvironment
        {
            ApplicationName = Assembly.GetEntryAssembly().GetName().Name
        };
        services.AddSingleton<IHostingEnvironment>(environment);
        services.Configure<RazorViewEngineOptions>(options =>
        {
            options.FileProviders.Clear();
            options.FileProviders.Add(new PhysicalFileProvider(Directory.GetCurrentDirectory()));
        });
        services.AddSingleton<ObjectPoolProvider, DefaultObjectPoolProvider>();
        services.AddSingleton<DiagnosticSource>(new DiagnosticListener("Microsoft.AspNetCore"));

        services.AddLogging();
        services.AddMvc();

        return services.BuildServiceProvider();
    }

You might need to add the Microsoft.Extensions.PlatformAbstractions package.

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