A Blue Prism project with custom DLLs: load DLL from everywhere

I admit, this is one of the most painful points when i work with Blue Prism. As explained in other posts about DLLs, we have to put class libraries into the root folder of Blue Prism in order to use classes.
This could be a problem when you don't have the rights to access Blue Prism root folder, so with the great Antonio Durante, we find a way to solve this problem using another forgotten beauty: the reflection.

Here you can download a little project in Visual Studio, which is composed of some lines of code which simply get the content of a editable PDF and return as a DataTable containing as many rows as lines of text found in the PDF.
This piece of code uses iTextSharp.dll to do the work so we have a depencency here.

public class Program
{
 public Program(string blablabla)
 {
  // This is a fake constructor
 }

 public static DataTable LoadPdf(string path)
 {
  List data = PdfHelper.ExtractTextFromInvoice(path);

  DataTable table = new DataTable();
  table.Columns.Add("Row", typeof(string));

  DataRow row11 = table.NewRow();
  row11["Row"] = "Yeah 1.1 version as well";
  table.Rows.Add(row11);

  foreach (string item in data)
  {
   DataRow row = table.NewRow();
   row["Row"] = item;
   table.Rows.Add(row);
  }

  return table;
 }

 static void Main(string[] args)
 {
    DataTable t = LoadPdf(@"C:\Users\v.valrosso\Downloads\test1.pdf");
 }
}

The code here is very simple, but just to see again how reflection work, i write also this code to test everything. As you can see i load only the assembly in a folder where you can find also the referenced DLL (i've used directly the Debug output folder of the dummy project)

class Program
{
 static void Main(string[] args)
 {
  string assemblyPath = @"C:\TFS\Test\Code\Poc.ReferencingCode\bin\Debug\Poc.ReferencingCode.dll";

  Assembly asm = Assembly.LoadFrom(assemblyPath);
  //Assembly asm = Assembly.Load(File.ReadAllBytes(assemblyPath));
  Type t = asm.GetType("Poc.ReferencingCode.Program");

  var methodInfo = t.GetMethod("LoadPdf", new Type[] { typeof(string) });
  if (methodInfo == null)
  {
   // never throw generic Exception - replace this with some other exception type
   throw new Exception("No such method exists.");
  }

  object o = Activator.CreateInstance(t);

  object[] parameters = new object[1];
  parameters[0] = @"C:\Users\v.valrosso\Downloads\test1.pdf";       

  DataTable r = (DataTable)methodInfo.Invoke(o, parameters);
  Console.WriteLine(r);
 }
}

After that we can just play with BP creating a new VBO just pasting the code and ... les jeux sont faits.

Just  a warning, BP locks the DLL so you have think something more smart (Antonio and I have developed something very very smart but sadly i cannot show you because of it's top secret).

As usual thanks to my colleague and friend Antonio Durante for the wonderful work we make together everyday.