Read string stored in Blob field

Discussion created by jcscott on Sep 19, 2014
Latest reply on Oct 29, 2018 by jcscott



I'm posting this here in case anyone else comes across this and needs a solution to reading string data stored in blobs.


First, i understand that this isn't the best method to be storing string/long text format, but it was best for my method and i suspect i'm not the only one who will want to do this!


In my case, i was required to store large text blocks into a geodatabase and wanted to keep everything contained into one simple row per-object.

I wasn't interested in either creating multiple rows to store a max of 255 chars or storing in another DB, so based on this i was able to store all my text in a Blob format.


I was a little stumped on how to read back this information in C# (python was a breeze), and there wasn't very much help i could find online for this.

So, with that in mind, the code below (with a little massaging) should be able to return a string store in a blob to a string type in C# if anyone is stuck.



private string getBlobText(IRow row, int blobrowint)
     //blobrowint is the integer location of the blobfield
     ESRI.ArcGIS.esriSystem.IMemoryBlobStream2 blobText = (ESRI.ArcGIS.esriSystem.IMemoryBlobStream2)row.get_Value(blobrowint);
     //creates a byte object equal to the size of the blob string
     int n = (int)blobText.Size;
     byte[] blobBytes = new Byte[n];

     //creates a variant of the blobtext as a object
     object blobObject = null;
     (commenttxt as ESRI.ArcGIS.esriSystem.IMemoryBlobStreamVariant).ExportToVariant(out blobObject);
     //converts the blobObject to a byte
     blobBytes = (byte[])blobObject;
     //translates the bytes to string
     string res = System.Text.Encoding.UTF8.GetString(blobBytes);