尝试下载Crystal Report PDF时出错

Question

我正在尝试为我的项目实施Crystal Reports

我的家庭控制器：

using System;
using System.Collections.Generic;
using System.Data.Entity;
using System.IO;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using Biblioteca.Models;
using CrystalDecisions.CrystalReports.Engine;

namespace Biblioteca.Controllers
{
    public class HomeController : Controller
    {
        private BibliotecaDatabase db = new BibliotecaDatabase();

        public ActionResult Index()
        {
            var totalesviewmodel = new TotalesViewModel();
            totalesviewmodel.MontoCopias = db.AlumnosList.Sum(o => o.Copias);
            totalesviewmodel.MontoImpresiones = db.AlumnosList.Sum(o => o.Impresiones);
            totalesviewmodel.DineroDeposito = db.AlumnosList.Sum(o => o.Deposito);
            totalesviewmodel.DineroSap = db.AlumnosList.Sum(o => o.Sap);
            totalesviewmodel.MontoCopiasMaestro = db.MaestrosList.Sum(o => o.Copias);
            totalesviewmodel.MontoImpresionesMaestro = db.MaestrosList.Sum(o => o.Impresiones);
            return View(totalesviewmodel);
        }

        public ActionResult Reports()
        {
            List<Alumno> allDatos = new List<Alumno>();
            using (BibliotecaEntities dc = new BibliotecaEntities())
            {
                allDatos = dc.Alumnos.ToList();
            }
            return View(allDatos);
        }

        public ActionResult ExportReport()
        {
            List<Alumno> allDatos = new List<Alumno>();
            using (BibliotecaEntities dc = new BibliotecaEntities())
            {
                allDatos = dc.Alumnos.ToList();
            }

            ReportDocument rd = new ReportDocument();
            rd.Load(Path.Combine(Server.MapPath("~/Reports"), "rpt_datos.rpt"));
            rd.SetDataSource(allDatos);

            Response.Buffer = false;
            Response.ClearContent();
            Response.ClearHeaders();

            try
            {
                Stream stream = rd.ExportToStream(CrystalDecisions.Shared.ExportFormatType.PortableDocFormat);
                stream.Seek(0, SeekOrigin.Begin);
                return File(stream, "application/pdf", "DatoList.pdf");
            }
            catch (Exception ex)
            {
                throw;
            }
        }

        public ActionResult Contact ()
        {
            ViewBag.Message = "Your contact page.";

            return View();
        }
    }
}

当我尝试下载报告的PDF文件时，我的项目在以下位置停止：

rd.SetDataSource(allDatos);

出现此错误：

mscorlib.dll中发生类型'System.Reflection.TargetInvocationException'的异常，但未在用户代码中处理

当我单击继续时，浏览器会显示：

ObjectContext实例已被处置，不能再用于需要连接的操作。

我究竟做错了什么？

Answer 1

这是因为您是在功能代码块的using范围之外编写此代码的：

rd.SetDataSource(allDatos);

尝试将这些代码行写入using代码块中，或者如果这不是问题，则可以删除using 。

希望这可以帮助。

Answer 2

omg，非常感谢，您为我提供了很多帮助！...答案：像这样在代码的最后关闭使用block：

using System;
using System.Collections.Generic;
using System.Data.Entity;
using System.IO;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using Biblioteca.Models;
using CrystalDecisions.CrystalReports.Engine;

namespace Biblioteca.Controllers
{
    public class HomeController : Controller
{
    private BibliotecaDatabase db = new BibliotecaDatabase();

    public ActionResult Index()
    {
        var totalesviewmodel = new TotalesViewModel();
        totalesviewmodel.MontoCopias = db.AlumnosList.Sum(o => o.Copias);
        totalesviewmodel.MontoImpresiones = db.AlumnosList.Sum(o => o.Impresiones);
        totalesviewmodel.DineroDeposito = db.AlumnosList.Sum(o => o.Deposito);
        totalesviewmodel.DineroSap = db.AlumnosList.Sum(o => o.Sap);
        totalesviewmodel.MontoCopiasMaestro = db.MaestrosList.Sum(o => o.Copias);
        totalesviewmodel.MontoImpresionesMaestro = db.MaestrosList.Sum(o => o.Impresiones);
        return View(totalesviewmodel);
    }

    public ActionResult Reports()
    {
        List<Alumno> allDatos = new List<Alumno>();
        using (BibliotecaEntities dc = new BibliotecaEntities())
        {
            allDatos = dc.Alumnos.ToList();
        }
        return View(allDatos);
    }

    public ActionResult ExportReport()
    {
        List<Alumno> allDatos = new List<Alumno>();
        using (BibliotecaEntities dc = new BibliotecaEntities())
        {
            allDatos = dc.Alumnos.ToList();


        ReportDocument rd = new ReportDocument();
        rd.Load(Path.Combine(Server.MapPath("~/Reports"), "rpt_datos.rpt"));
        rd.SetDataSource(allDatos);

        Response.Buffer = false;
        Response.ClearContent();
        Response.ClearHeaders();

        try
        {
            Stream stream = rd.ExportToStream(CrystalDecisions.Shared.ExportFormatType.PortableDocFormat);
            stream.Seek(0, SeekOrigin.Begin);
            return File(stream, "application/pdf", "DatoList.pdf");
        }
        catch (Exception ex)
        {
            throw;
        }
    }

    public ActionResult Contact ()
    {
        ViewBag.Message = "Your contact page.";

        return View();
    }
}
  }
  }