如何使用FastReport Core以PDF格式下载报表

本文将展示如何创建一个按钮，实现一键将报表从浏览器下载到本地。

本文将展示如何创建一个按钮，实现一键将报表从浏览器下载到本地。我们将在最终文件的功能中使用导出为PDF（当然你可以使用任何其他格式）。

首先，创建一个ASP.NET Core Web Application项目并添加下列库：FastReport Core、Microsoft.EntitiyFrameworkCore.Sqlite以及Microsoft.EntitiyFrameworkCore.Sqlite.Design。这样，你就有了已安装好的以下软件包：

让我们预先处理数据。我们需要SQLite数据库 – fastreport.db。可以从示范项目“C: Program Files (x86)FastReportsFastReport.NetDemosCoreFastReportCore.MVC” 中获取。将数据库直接添加到项目的根目录。另外，我们从项目文件夹“C:Program Files (x86)FastReportsFastReport.NetDemosReports”中添加报告模板“Simple List.frx”。

现在，在Models文件夹中，添加一个新的类。我们称之为ApplicationDbContext.cs。从名字你大概就能看出来了 – 这是数据的上下文。这是它的内容：

using Microsoft.EntityFrameworkCore;using System;using System.Data;using System.Reflection;namespace FRCore{ public class ApplicationDbContext : DbContext { public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options) : base(options) { } public ApplicationDbContext() { } public DbSet<Employees> Employees { get; set; } // Get the data set public DataSet GetDataSet(string name) { DataSet set = new DataSet(name); set.Tables.Add(GetTable(Employees, "Employees")); return set; } // Set the primary key protected override void OnModelCreating(ModelBuilder modelBuilder) { modelBuilder.Entity<Employees>(entity => { entity.HasKey(e => e.EmployeeId) .HasName("sqlite_autoindex_employees_1"); }); } // Set the data source protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder) {#warning To protect potentially sensitive information in your connection string, you should move it out of source code. See http://go.microsoft.com/fwlink/inkId=723263 for guidance on storing connection strings. optionsBuilder.UseSqlite(@"data source= fastreport.db"); } // Get the table you need to create a report. In fact, the method of converting IQuerable into a DataTable static DataTable GetTable<TEntity>(DbSet<TEntity> table, string name) where TEntity : class { DataTable result = new DataTable(name); PropertyInfo[] infos = typeof(TEntity).GetProperties(); foreach (PropertyInfo info in infos) { if (info.PropertyType.IsGenericType && info.PropertyType.GetGenericTypeDefinition() == typeof(Nullable<>)) result.Columns.Add(new DataColumn(info.Name, Nullable.GetUnderlyingType(info.PropertyType))); else result.Columns.Add(new DataColumn(info.Name, info.PropertyType)); } foreach (var el in table) { DataRow row = result.NewRow(); foreach (PropertyInfo info in infos) if (info.PropertyType.IsGenericType && info.PropertyType.GetGenericTypeDefinition() == typeof(Nullable<>)) { object t = info.GetValue(el); if (t == null) t = Activator.CreateInstance(Nullable.GetUnderlyingType(info.PropertyType)); row[info.Name] = t; } else row[info.Name] = info.GetValue(el); result.Rows.Add(row); } return result; } } // The Employees table model public class Employees { public int EmployeeID { get; set; } public int EmployeeId { get; set; } public string LastName { get; set; } public string FirstName { get; set; } public string Title { get; set; } public string TitleOfCourtesy { get; set; } public System.DateTimeBirthDate { get; set; } public System.DateTimeHireDate { get; set; } public string Address { get; set; } public string City { get; set; } public string Region { get; set; } public string PostalCode { get; set; } public string Country { get; set; } public string HomePhone { get; set; } public string Extension { get; set; } public byte[] Photo { get; set; } public string Notes { get; set; } public intReportsTo { get; set; } }}

在这个类中（在连接到数据库后）我们得到一组数据并将其转换为一个DataTable，这是FastReport生成报表所需的。将在报表中使用的Employees表的模型由一个单独的类表示。

现在我们开始编辑HomeController.cs。

using System.Diagnostics;using Microsoft.AspNetCore.Mvc;using FRCore.Models;using FastReport;using FastReport.Export.Html;using System.IO;using System.Text;using FastReport.Export.Pdf;using System.Data;namespace FRCore.Controllers{ public class HomeController : Controller { public Report report = new Report(); private ApplicationDbContext _context = new ApplicationDbContext(); public ApplicationDbContext GetContext() { return _context; } public IActionResult Index() { DataSet dataSet = new DataSet(); dataSet = GetContext().GetDataSet("NorthWind"); report.Report.RegisterData(dataSet, "NorthWind"); report.Report.Load("Simple List.frx"); report.Prepare(); HTMLExport export = new HTMLExport(); export.Layers = true; using (MemoryStream ms = new MemoryStream()) { export.EmbedPictures = true; export.Export(report, ms); ms.Flush(); ViewData["Report"] = Encoding.UTF8.GetString(ms.ToArray()); ViewData["ReportName"] = "Simple List.frx"; } return View(); } public IActionResult Pdf() { System.Data.DataSet dataSet = new System.Data.DataSet(); dataSet = GetContext().GetDataSet("NorthWind"); report.Report.RegisterData(dataSet, "NorthWind"); report.Report.Load("Simple List.frx"); report.Prepare(); PDFExport export = new PDFExport(); using (MemoryStream ms = new MemoryStream()) { export.Export(report, ms); ms.Flush(); return File(ms.ToArray(), "application/pdf", Path.GetFileNameWithoutExtension("Simple List") + ".pdf"); } } }}

Index方法只是以html格式显示报表，而PDF方法则生成一个用于下载的PDF文件。这两种方法都使用报表的数据上下文。

现在改变Index.cshtml的显示形式：

@{ ViewData["Title"] = "Home Page";}@if (ViewData.ContainsKey("ReportName")){ <a class="btn btn-danger" asp-controller="Home" asp-action="Pdf" asp-route-report="@ViewData["ReportName"]">Download PDF</a>}@if (ViewData.ContainsKey("Report")){ @Html.Raw(ViewData["Report"])}

我们首先添加了一个PDF下载按钮，然后显示报表。

运行应用程序：

我们按下“下载PDF”按钮，并以PDF格式下载报表文件。总而言之，实现起来相当简单。

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如何使用FastReport Core以PDF格式下载报表

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