Feature: MS Excel (xlsx) Import/Export

Microsoft Excel files can be used to import/export devices. Several
import bugs were also fixed in the process.

Disco.Web.Extensions/Disco.Web.Extensions.csproj

@@ -103,6 +103,8 @@
     <Compile Include="DataModelExtension\DocumentTemplateExtensions.cs" />
     <Compile Include="DataModelExtension\JobSubTypeExtensions.cs" />
     <Compile Include="DataModelExtension\JobTypeExtensions.cs" />
+    <Compile Include="MvcExtensions\File\FileContentSpanResult.cs" />
+    <Compile Include="MvcExtensions\File\FileExtensions.cs" />
     <Compile Include="MvcExtensions\JsonNet\JsonDotNetValueProviderFactory.cs" />
     <Compile Include="MvcExtensions\JsonNet\JsonNetResult.cs" />
     <Compile Include="MvcExtensions\PartialCompiled\PartialCompiledHtmlExtensions.cs" />

Disco.Web.Extensions/MvcExtensions/File/FileContentSpanResult.cs

@@ -0,0 +1,34 @@
+using System;
+using System.Web;
+using System.Web.Mvc;
+
+namespace Disco.Web.Extensions
+{
+    public class FileContentSpanResult : FileResult
+    {
+        public byte[] FileBuffer { get; private set; }
+        public int Start { get; private set; }
+        public int Length { get; private set; }
+
+        public FileContentSpanResult(byte[] fileBuffer, int start, int length, string contentType) : base(contentType)
+        {
+            if (fileBuffer == null)
+                throw new ArgumentNullException(nameof(fileBuffer));
+
+            if (start < 0 || start >= fileBuffer.Length)
+                throw new ArgumentOutOfRangeException(nameof(start));
+
+            if (start + length > fileBuffer.Length)
+                throw new ArgumentOutOfRangeException(nameof(length));
+
+            FileBuffer = fileBuffer;
+            Start = start;
+            Length = length;
+        }
+
+        protected override void WriteFile(HttpResponseBase response)
+        {
+            response.OutputStream.Write(this.FileBuffer, Start, Length);
+        }
+    }
+}

Disco.Web.Extensions/MvcExtensions/File/FileExtensions.cs

@@ -0,0 +1,17 @@
+using System.Web.Mvc;
+
+namespace Disco.Web.Extensions
+{
+    public static class FileExtensions
+    {
+
+        public static FileContentSpanResult File(this IController controller, byte[] fileBuffer, int start, int length, string contentType, string fileDownloadName)
+        {
+            return new FileContentSpanResult(fileBuffer, start, length, contentType)
+            {
+                FileDownloadName = fileDownloadName
+            };
+        }
+
+    }
+}