如何在Angular中从数据库下载和保存ASP.NET Core API中的pdf文件？

Question

我的Angular项目无法通过ASP.NET core API下载（另存为）pdf文件。pdf文件存储在SQL Server中。

我尝试了stackoverflow中发布的许多方法，但没有一种对我有效。有些示例下载了一个pdf文件，但如果试图打开它，它会发现一个错误“..不支持..损坏”。

API（我倾向于返回一行，而不是仅返回一个vaule字节[])

[HttpGet]
        [Route("detail/{studentid:int}/{reportSeq:int}")]
        public async Task<ActionResult<byte[]>> GetStudentAcademicReport2(int StudentID, int ReportSeq)
        {            
            var report = await _context.AcademicReportDetails.FromSql("select * from [dbo].[ufnStudentAcademicReport] (8213, 8158)").FirstOrDefaultAsync();
            if (report == null)
            {
                return NotFound();
            }
            return report.ReportContent;
        }

1. 不工作在角度

this.httpclient.get（“https：//localhost:44369/api/values/detail/8213/8158”，{responseType:'blob'}）
.subscribe(response=>{console.log（响应）；

  const url = window.URL.createObjectURL(new Blob([response]));
  const link = document.createElement('a');
  link.href = url;
  link.setAttribute('download', 'file.pdf');
  document.body.appendChild(link);
  link.click();

this.httpclient.get（“http：//localhost:5000/api/studentAcademicReports/detail/8213/8158”,{responseType:'arraybuffer'}）
.subscribe(response=>{console.log（响应）；

  const file = new Blob([response], {type: 'application/pdf'});
  const fileURL = window.URL.createObjectURL(file);

  let objectURL = 'data:image/jpeg;base64,' +  response;
  let fileURL2 = this.sanitizer.bypassSecurityTrustUrl(objectURL); 

  const link = document.createElement('a');
  link.href = fileURL;
  link.download = 'sample.pdf';
  link.click();

在Windows窗体项目中工作

cmd.commandtext=“Select*from[dbo].[ufnStudentAcademicReport](8213,8158）”；Cmd.CommandType=CommandType.Text；

                if (cmd.Connection.State != ConnectionState.Open)
                {
                    cmd.Connection.Open();
                }

                DbDataReader read = cmd.ExecuteReader();
                if (read.HasRows)
                {
                    while (read.Read())
                    {
                        byte[] b = null;                                
                        b = (byte[])read.GetValue(read.GetOrdinal("ReportContent"));
                        System.IO.File.WriteAllBytes(@"c:\temp\test.pdf", b);    
                    }    
                }

无法通过API在Windows窗体项目中工作

        var content = await NewResponse.Content.ReadAsByteArrayAsync();

        System.IO.File.WriteAllBytes(@"c:\temp\test111.pdf", content);

Answer 1

当您从ASP.NET Core操作返回byte[]时，它的结果是base64编码的，这就是您得到一个“损坏”文件的原因。您必须从action返回fileResult，以便让框架正确处理二进制数据

public async Task<FileResult> GetStudentAcademicReport2(int StudentID, int ReportSeq)
{
    var report = await _context.AcademicReportDetails.FromSql("select * from [dbo].[ufnStudentAcademicReport] (8213, 8158)").FirstOrDefaultAsync();
    if (report == null)
    {
        return NotFound();
    }
    return File(report.ReportContent, "application/pdf", "test.pdf");
}