Where VSTO creates the project folder



Julie wrote to me with a problem about where VSTO creates its DLLs and how they get trusted. Hopefully this will help 😉

The other day I blogged about how referenced assemblies are copied around, but there’s another piece to the puzzle. If you use the New Project wizard to create a VSTO project and elect to create a new document, the wizard places the document in the same folder as the project so you end up with this kind of hierarchy:




// Root project folder

C:My_DocsUserVS_ProjsProject

 




  // VS Project files

  ThisDocument.vb

  Project.sln

  etc.

 




  // The document

  Project.doc

 




  // VS output folder

  Bin

    Project.dll

    Project.pdb

 




  // VS build folder

  Obj

    Debug

      Project.dll

      Project.pdb

 




  // VSTO output folder

  Project_bin

    Project.dll

    Project.pdb

In this case, VSTO will setup the security policy to trust C:My_DocsUserVS_ProjsProjectProject_binProject.dll and when you run the solution it will run the document C:My_DocsUserVS_ProjsProjectProject.doc which will try and load the assembly through the relative path .Project_bin.

If you choose to use an existing document, something a bit different happens. VSTO still creates the standard VS project hierarchy, but the Project_bin is created relative to the original document’s location. You end up with something like this:




// Root project folder

C:My_DocsUserVS_ProjsProject

 




  // VS Project files

  ThisDocument.vb

  Project.sln

  etc.

 




  // Note: no document!

 




  // VS output folder

  Bin

    Project.dll

    Project.pdb

 




  // VS build folder

  Obj

    Debug

      Project.dll

      Project.pdb

 




// Document folder

C:My_DocsUserDesktop

 




  // The document

  Project.doc

 




  // VSTO output folder

  Project_bin

    Project.dll

    Project.pdb

In this case, VSTO builds the DLL into the project folder, but then copies it (along with any referenced assemblies) to the document’s location as a post-build step. It will also setup the security policy to trust C:My_DocsUserDesktopProject_binProject.dll and when you run the solution it will run the document C:My_DocsUserDesktopProject.doc which will try and load the assembly through the relative path .Project_bin. If you try and set policy to trust the VS project location (C:My_DocsUserVS_ProjsProject*) it won’t have any effect since the document / assembly is not loaded from there.

If you want to know where your assembly comes from, it’s pretty easy using the CodeBase property of the Assembly object:




  ‘ Display the location of the DLL


  

Private

Sub


ThisWorkbook_Open

()
Handles
ThisWorkbook.Open




    MessageBox.Show(Me.GetType.Assembly.CodeBase)




  
End

Sub

(Of course your code needs to be trusted to display this info…)

Comments (4)

  1. Julie says:

    Yes this is exactly what it *WAS* doing… but now I’ve discovered that if I go in and set the assembly link to the directory I’m planning on deploying to BEFORE I initially run the template I’m designing (that I based on an existing document), it actually doesn’t do that.

    So, I have the following directories:

    C:MSPDASBaseTemplates (.dot files)

    C:MSPDASReferences (dependency .dlls)

    C:MSPDASTemplates (VSTO project files)

    C:MSPDASTemplateAssemblies (VSTO dll files)

    Now when I compile, the VSTO files get put in the template folder directory under c:MSPDASTemplates, BaseTemplates continues to contain only my .dot files and the VSTO DLLs are going into c:MSPDASTemplateAssemblies

    I really like this…not quite sure if its supposed to be doing it but I like it nonetheless 🙂

  2. Peter Torr says:

    Yes, if you manually over-ride the AssemblyLinkLocation property then VSTO will put the stuff wherever you ask for it (and update policy to trust that location too).

  3. Peter Torr says:

    Oh yeah, I think that VSTO 2 will change this behaviour a bit and will always copy the document into the project directory and then execute a read-only copy from the _bin directory… due to the new "designer hosted in VS" model things had to be changed around a bit.

  4. Today is a complete success. Finally finished debugging the core architecture, I was able to finish one of our most complicated templates and begin working on the pile of 30 pilot templates (so far I have 7 of those done)….