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Entity Data Model (edmx) services returning sql server 2008 image type as binary access by iPhone SDK through NSURLConnection

Answer 1

+1 A:

That return is a JSON payload (application/json) with a base64 encoded image on a UTF-8 charset. If you don't want to parse JSON on your own, there is json-framework you could try, or TouchJSON.

Remus Rusanu 2010-03-10 17:34:19

I realize its json, and I can parse that fine. The problem is when I try to create a UIImage from the string of image data:UIImage* image = [UIImage imageWithData:[NSData dataWithBase64EncodedString:pictureDataString]];where dataWithBase64EncodedString is a decoding method found on the web, it doesn't work. The UIImage is always nil, meaning the UIImage class couldnt convert the decoded string to any image data. I've tried encoding and then decoding a local UIImage and that seems to work fine, just can't get the data from the json packet to decode to anything.

Bryan 2010-03-10 20:39:34

Take the base64 encoded text and go to online decoder, like http://www.motobit.com/util/base64-decoder-encoder.asp. With the text in your post, the decoded result is binary that contains this string embeded `System.Drawing, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a` which tells me its a serialized CLR System.Drawing, not a valid image format (.png, .jpg, .gif or even .bmp). Apparently the EDMX is intended to be consumed only by another CLR app... which does not suprise me at least...

Remus Rusanu 2010-03-10 20:59:50

BTW, probably this is isn't EDMX at fault here, most likely the original content in the database is saved as a serialized Drawing instead of a proper image format like `Image.Save(ImageFormat.Png)` or something similar, so you'll have to track down the app that saves the image in the db and fix that.

Remus Rusanu 2010-03-10 21:10:52

Awesome, good catch. Thanks and I'll let ya know what I find

Bryan 2010-03-10 21:42:07

Answer 2

A:

Here is the .net image related code:

Codes for saving images into database
System.Drawing.Image img = System.Drawing.Image.FromFile(imgPath);// “imgPath” is the file path of a temporary image uploaded by a user.
student.image = new System.Data.Linq.Binary(Utility.Convertor.ImageToByteArray(img));
img.Dispose();
Codes for writing image bytes from server to client
System.Drawing.Image img = Utility.Convertor.ByteArrayToImage(stu.image.ToArray());
Response.ContentType = ("image/" + Utility.Gadget.GetImageFormat(img));
MemoryStream ms = new MemoryStream();
img.Save(ms, img.RawFormat);
byte[] result = ms.ToArray();
ms.Close();
ms.Dispose();
Response.BinaryWrite(result);

Below are encapsulated methods for storing / restoring students’ images:
Serializer for serializing a image to bytes
/// 
/// Convert a System.Drawing.Image object to byte array formatted by System.Runtime.Serialization.Formatters.Binary.BinaryFormatter.
/// 
/// 
/// 
public static byte[] ImageToByteArray(System.Drawing.Image imageIn)
{
      BinaryFormatter sf = new BinaryFormatter();
      MemoryStream ms = new MemoryStream();
      sf.Serialize(ms, imageIn);
      byte[] result = ms.ToArray();
      ms.Close();
      ms.Dispose();
      return result;
}
Deserializer for restoring a image from bytes
/// 
/// Convert a byte array formatted by System.Runtime.Serialization.Formatters.Binary.BinaryFormatter to a System.Drawing.Image object.
/// 
/// 
/// 
public static System.Drawing.Image ByteArrayToImage(byte[] byteArrayIn)
{
       BinaryFormatter sf = new BinaryFormatter();
       MemoryStream ms = new MemoryStream(byteArrayIn);
       System.Drawing.Image returnImage = (System.Drawing.Image)sf.Deserialize(ms);
       ms.Close();
       ms.Dispose();
       return returnImage;
}

Bryan 2010-03-11 19:48:57

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Entity Data Model (edmx) services returning sql server 2008 image type as binary access by iPhone SDK through NSURLConnection

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