Forum Discussion

mugheessiddiqui's avatar
mugheessiddiqui
Contributor
8 years ago

Read Blob object from DB and convert to System.Collection.Generic.List type of object.

I have scenario where database field stores a System.Collection.Generic.List of Double object. Now I want to read a BLOB object from database field and convert it to list of Array or any type collect...
  • tristaanogre's avatar
    tristaanogre
    8 years ago

    Rather than "Value", you might want to use the GetChunk method.  What you'll need to do is get the ActualSize of the field and then use GetChunk to retrieve it.  I've not tested this but it might look something like this:

     rs.MoveFirst();
var blobSize = rs.Fields("slices").ActualSize;
  var blob = rs.Fields("slices").GetChunk(blobSize);
mugheessiddiqui's avatar
mugheessiddiqui
Contributor

Thanks Now I have gotten Blob object.

 

Second Issue is to Cast the Blob object in some list/dictionary type object of JavaScript for traversing. As I told you we have stored blob object type of System.Collection.Generic.List of Double.

 

I have found the following description of System.Collection.Generic.List that takes the "<CLRType> collection" object. I don't know how to define <CLRType> collection object.

 

Description: System.Collection.Generic.List`1 zctor_3(<CLRType> collection);

 

So far code looks like and I get type Mismatch error.

 

rs.MoveFirst();

var blobSize = rs.Fields("slices").ActualSize;
var blob = rs.Fields("slices").GetChunk(blobSize);


var objList = Aliases.appName.AppDomain("appUI.exe").dotNET.System_Collections_Generic.List_1.zctor_3(blob); // Gives "Type Mismatch Error"

 

 

tristaanogre's avatar
tristaanogre
Esteemed Contributor
8 years ago

if your Blob is an image, it's not a collection.  A collection is an object that has fields and properties and items.  At least, that's my understanding.

 

I don't know the specific collection object you are trying to use so I can't help you further.

  • mugheessiddiqui's avatar
    mugheessiddiqui
    Contributor
    8 years ago

    No Blob is not an image, it's an serialized object of System.Collections.Generic.List.