实体框架将Blob数据读入html img [英] Entity Framework Reading Blob data into html img

问题描述

我试图将blob数据读入html图像对象。我想避免任何文件创建和处理（除非不可避免）。我目前的代码是：

数据表：

  studentID |名字| photo 
 ---------- + ----------- + ------------ 
 93 | Eva | Blob data 
  

StudentEntity.cs：

  public class ShortStudent 
 {
 public string firstname {get;组; } 
 public int studentid {get;组; } 
 public string photo {get;组; } 
} 
  

然后将这些数据发送到视图如下

  ShortStudent sd = new ShortStudent（）; 
 
 sd.firstname =<来自db的名称>; 
 sd.photo = Convert.ToBase64String（Serialize（< Blob data from db>））; 
 .... 
返回Json（sd，JsonRequestBehavior.AllowGet）; 
  

序列化：

  private byte [] Serialize（string p）
 {
 var binaryFormatter = new BinaryFormatter（）; 
 var ms = new MemoryStream（）; 
 binaryFormatter.Serialize（ms，p）; 
返回ms.ToArray（）; 
 
  

Javascript：

 < img src =data：image / gif; base64，＃= data.photo＃alt =< image not found> /> 
  

如果我放入一些示例数据，它会正确显示，但不会显示来自数据库的数据（db数据在序列化和转换之后是示例数据的3倍）

解决方案

我只需将图像数据读为byte []，而不是

StudentEntity.cs

 公共类ShortStudent 
 {
公共字符串firstname {get;组; } 
 public int studentid {get;组; } 
 public byte [] photo {get;组; } 
} 
  

并更改

  sd.photo = Convert.ToBase64String（Serialize（< Blob data from db>））; 
  

至

  string img = Convert.ToBase64String（< Blob data from db>）; 
  

并发送至JSon

I am trying to read blob data into an html image object. I want to avoid any file creation and handling in the process (unless its unavoidable). My current code is

Data table:

studentID | firstname | photo
----------+-----------+------------
93        |Eva        | Blob data

StudentEntity.cs:

public class ShortStudent
{
    public string firstname { get; set; }
    public int studentid { get; set; }
    public string photo { get; set; }
}

This data is then sent to the view as follows

ShortStudent sd = new ShortStudent();

sd.firstname = <name from db>;
sd.photo = Convert.ToBase64String(Serialize(<Blob data from db>));
....
return Json(sd, JsonRequestBehavior.AllowGet);

Serialize:

private byte[] Serialize(string p)
{
    var binaryFormatter = new BinaryFormatter();
    var ms = new MemoryStream();
    binaryFormatter.Serialize(ms, p);
    return ms.ToArray();
}

Javascript:

<img src="data:image/gif;base64,#= data.photo #" alt="<image not found>" />

If I put in some example data it displays correctly but not the data that comes from database (db data after serializing and conversion is 3 times the example data in size)

解决方案

I simply had to read image data as byte[] instead of string and it worked.

StudentEntity.cs

public class ShortStudent
{
  public string firstname { get; set; }
  public int studentid { get; set; }
  public byte[] photo { get; set; }
}

and change

sd.photo = Convert.ToBase64String(Serialize(<Blob data from db>));

to

string img = Convert.ToBase64String(<Blob data from db>);

and send in JSon

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