How to save a file into DB by BlobStream ?

Key Words: ArcGIS , BlobStream , DataBase

 

HowTo:  Save a .lyr file in a database using ArcObjects

Article ID:	23529
Software:	ArcGIS - ArcEditor 8.1, 8.1.2, 8.2, 8.3, 9.0 ArcGIS - ArcInfo 8.1, 8.1.2, 8.2, 8.3, 9.0 ArcGIS - ArcView 8.1, 8.1.2, 8.2, 8.3, 9.0
Platforms:	N/A

Summary

This sample code shows how to save a .lyr file as a blob in a database. Any object that supports persistance can be saved in this manner.

Procedure

1. Create an access database and name it BLOB.
2. Create a new table in BLOB.mdb called Layers and add a blob field called Layers.
3. Open ArcMap and add the layer file to the map.
4. Create a new UIButtonControl.-show me-
   
   

   A. Select Tools > Customize to open the Customize dialog box.
   B. Click the Commands tab.
   C. Select UIControls from the Categories list box.
   D. Select Untitled from the Save In dropdown list to save the button to this map document. Select Normal to save the button to all ArcMap documents on the machine.
   E. Click New UIControl.
   F. Select UIButtonControl and Create.
   G. Drag the new UIButtonControl to the toolbar of choice.
   H. Close the Customize dialog box.
   
   
   
    For information on creating a UIControl, see the ArcGIS Desktop Help topic "How to create custom commands with VBA."
   
   
5. Right-click the UIButtonControl and select View Source.
6. Copy the following code into the UIButtonControl's Click event:
   
   

     ' Get the IPersistStream for the 1st Layer from the map
                   
     Dim pMxDoc As IMxDocument
                   
     Set pMxDoc = ThisDocument
                   
   
                   
     Dim pPersist As IPersistStream
                   
     Set pPersist = pMxDoc.FocusMap.Layer(0)
                   
   
                   
     ' Now persist the layer to the memory blob stream
                   
     Dim pMemoryStream As IMemoryBlobStream
                   
     Set pMemoryStream = New MemoryBlobStream
                   
   
                   
     pPersist.Save pMemoryStream, False
                   
   
                   
     ' Finally save the blob into the database
                   
     Dim pWorkspaceFactory As IWorkspaceFactory
                   
     Set pWorkspaceFactory = New AccessWorkspaceFactory
                   
   
                   
     Dim pFeatureWorkspace As IFeatureWorkspace
                   
     Set pFeatureWorkspace =
                   
   pWorkspaceFactory.OpenFromFile("C:\Source\BLOB.mdb", 0)
                   
   
                   
   Dim pTable As ITable
                   
     Set pTable = pFeatureWorkspace.OpenTable("Layers")
                   
   
                   
     Dim pRow As IRow
                   
     Set pRow = pTable.CreateRow
                   
   
                   
     pRow.Value(pRow.Fields.FindField("Layers")) = pMemoryStream
                   
     pRow.Store

   
   
7. To add the saved .lyr file to the map add another button to ArcMap following step 4 above and add the code below to its click event:
   
   

     ' Finally save the blob into the database
                   
     Dim pWorkspaceFactory As IWorkspaceFactory
                   
     Set pWorkspaceFactory = New AccessWorkspaceFactory
                   
   
                   
     Dim pFeatureWorkspace As IFeatureWorkspace
                   
   
                   
   
                   
     Set pFeatureWorkspace =
                   
   pWorkspaceFactory.OpenFromFile("C:\Source\BLOB.mdb", 0)
                   
   
                   
     Dim pTable As ITable
                   
     Set pTable = pFeatureWorkspace.OpenTable("Layers")
                   
   
                   
     Dim pCursor As ICursor
                   
     Set pCursor = pTable.Search(Nothing, False)
                   
   
                   
     Dim pRow As IRow
                   
     Set pRow = pCursor.NextRow
                   
   
                   
     If (pRow Is Nothing) Then Exit Sub
                   
   
                   
     Dim pMemoryStream As IMemoryBlobStream
                   
     Set pMemoryStream = pRow.Value(pRow.Fields.FindField("Layers"))
                   
   
                   
     Dim pLayer As ILayer
                   
     Set pLayer = New FeatureLayer
                   
   
                   
     Dim pPersist As IPersistStream
                   
     Set pPersist = pLayer
                   
   
                   
     pPersist.Load pMemoryStream
                   
   
                   
     Dim pMxDoc As IMxDocument
                   
     Set pMxDoc = ThisDocument
                   
   
                   
     pMxDoc.FocusMap.AddLayer pLayer