Store converted body as Variant

Update WebHelpers and WebRequest to allow ConvertToFormat to return byte arrays rather than only a string, to be able to use it to upload binary data, e.g. images

Closes #146

Author: ipopov001

src/WebHelpers.bas

@@ -475,10 +475,10 @@ Public Sub LogRequest(Client As WebClient, Request As WebRequest)
             Debug.Print "Cookie: " & web_KeyValue("Key") & "=" & web_KeyValue("Value")
         Next web_KeyValue
 
-        If Request.Body <> "" Then
-            Debug.Print vbNewLine & Request.Body
+        If Not IsEmpty(Request.Body) Then
+            Debug.Print vbNewLine & CStr(Request.Body)
         End If
-        
+
         Debug.Print
     End If
 End Sub
@@ -740,10 +740,10 @@ End Function
 ' @param {Dictionary|Collection|Variant} Obj
 ' @param {WebFormat} Format
 ' @param {String} [CustomFormat] Name of registered custom converter
-' @return {String}
+' @return {Variant}
 ' @throws 11001 - Error during conversion
 ''
-Public Function ConvertToFormat(Obj As Variant, Format As WebFormat, Optional CustomFormat As String = "") As String
+Public Function ConvertToFormat(Obj As Variant, Format As WebFormat, Optional CustomFormat As String = "") As Variant
     On Error GoTo web_ErrorHandling
 
     Select Case Format
@@ -761,9 +761,9 @@ Public Function ConvertToFormat(Obj As Variant, Format As WebFormat, Optional Cu
         Set web_Converter = web_GetConverter(CustomFormat)
         web_Callback = web_Converter("ConvertCallback")
 
-        If web_Converter.Exists("web_Instance") Then
+        If web_Converter.Exists("Instance") Then
             Dim web_Instance As Object
-            Set web_Instance = web_Converter("web_Instance")
+            Set web_Instance = web_Converter("Instance")
             ConvertToFormat = VBA.CallByName(web_Instance, web_Callback, VBA.vbMethod, Obj)
         Else
             ConvertToFormat = Application.Run(web_Callback, Obj)

src/WebRequest.cls

@@ -56,7 +56,7 @@ Private web_pResponseFormat As WebFormat
 Private web_pCustomRequestFormat As String
 Private web_pCustomResponseFormat As String
 Private web_pBody As Variant
-Private web_pConvertedBody As String
+Private web_pConvertedBody As Variant
 Private web_pContentType As String
 Private web_pAccept As String
 Private web_pContentLength As Long
@@ -230,7 +230,7 @@ Public Property Let RequestFormat(Value As WebFormat)
         web_pRequestFormat = Value
 
         ' Clear cached converted body
-        web_pConvertedBody = ""
+        web_pConvertedBody = Empty
     End If
 End Property
 
@@ -266,7 +266,7 @@ Public Property Let ResponseFormat(Value As WebFormat)
         web_pResponseFormat = Value
 
         ' Clear cached converted body
-        web_pConvertedBody = ""
+        web_pConvertedBody = Empty
     End If
 End Property
 
@@ -298,7 +298,7 @@ Public Property Let CustomRequestFormat(Value As String)
         web_pCustomRequestFormat = Value
 
         ' Clear cached converted body
-        web_pConvertedBody = ""
+        web_pConvertedBody = Empty
 
         If Value <> "" Then
             web_pRequestFormat = WebFormat.Custom
@@ -334,7 +334,7 @@ Public Property Let CustomResponseFormat(Value As String)
         web_pCustomResponseFormat = Value
 
         ' Clear cached converted body
-        web_pConvertedBody = ""
+        web_pConvertedBody = Empty
 
         If Value <> "" Then
             ResponseFormat = WebFormat.Custom
@@ -461,7 +461,7 @@ Public Property Get Body() As Variant
     If Not VBA.IsEmpty(web_pBody) Then
         If VBA.VarType(web_pBody) = vbString Then
             Body = web_pBody
-        ElseIf web_pConvertedBody = "" Then
+        ElseIf IsEmpty(web_pConvertedBody) Then
             ' Convert body and cache
             Body = WebHelpers.ConvertToFormat(web_pBody, Me.RequestFormat, Me.CustomRequestFormat)
             web_pConvertedBody = Body
@@ -471,11 +471,11 @@ Public Property Get Body() As Variant
     End If
 End Property
 Public Property Let Body(Value As Variant)
-    web_pConvertedBody = ""
+    web_pConvertedBody = Empty
     web_pBody = Value
 End Property
 Public Property Set Body(Value As Variant)
-    web_pConvertedBody = ""
+    web_pConvertedBody = Empty
     Set web_pBody = Value
 End Property
 
@@ -697,7 +697,7 @@ Public Sub AddBodyParameter(Key As Variant, Value As Variant)
     End If
 
     ' Clear cached converted body
-    web_pConvertedBody = ""
+    web_pConvertedBody = Empty
 End Sub
 
 ''