Added support for saving packages as Excel templates (.xltx/.xltm)

src/EPPlus/Constants/ContentTypes.cs

@@ -19,7 +19,11 @@ internal class ContentTypes
         internal const string contentTypeWorkbookMacroEnabled = "application/vnd.ms-excel.sheet.macroEnabled.main+xml";
         internal const string contentTypeSharedString = @"application/vnd.openxmlformats-officedocument.spreadsheetml.sharedStrings+xml";
         internal const string contentTypeMetaData = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheetMetadata+xml";
-
+
+        //Template
+        internal const string contentTypeTemplateDefault = @"application/vnd.openxmlformats-officedocument.spreadsheetml.template.main+xml";
+        internal const string contentTypeTemplateMacroEnabled = "application/vnd.ms-excel.template.macroEnabled.main+xml";
+
         //Theme
         internal const string contentTypeThemeOverride = "application/vnd.openxmlformats-officedocument.themeOverride+xml";
         internal const string contentTypeTheme = @"application/vnd.openxmlformats-officedocument.theme+xml";

src/EPPlus/Enums.cs

@@ -252,4 +252,21 @@ public enum eWorkbookVisibility
         /// </summary>
         Visible
     }
+    /// <summary>
+    /// Specifies the document format to use when saving a package.
+    /// </summary>
+    public enum eDocumentFormat
+    {
+        /// <summary>
+        /// A standard Excel workbook (.xlsx, or .xlsm if the workbook contains a VBA project).
+        /// This is the default format.
+        /// </summary>
+        Workbook,
+        /// <summary>
+        /// An Excel template (.xltx, or .xltm if the workbook contains a VBA project).
+        /// When opened in Excel, a template creates a new workbook based on its contents 
+        /// rather than opening the template file itself for editing.
+        /// </summary>
+        Template
+    }
 }

src/EPPlus/ExcelPackage.cs

@@ -28,6 +28,8 @@ Date               Author                       Change
 
 #if (!NET35)
 using OfficeOpenXml.SensitivityLabels;
+using System.Linq;
+
 #endif
 
 #if (Core)
@@ -881,39 +883,6 @@ internal void SavePart(Uri uri, XmlDocument xmlDoc)
             var xmlWriter = XmlWriter.Create(stream, xmlSettings);
             xmlDoc.Save(xmlWriter);
         }
-        /// <summary>
-		/// Saves the XmlDocument into the package at the specified Uri.
-		/// </summary>
-		/// <param name="uri">The Uri of the component</param>
-		/// <param name="xmlDoc">The XmlDocument to save</param>
-        internal void SaveWorkbook(Uri uri, XmlDocument xmlDoc)
-        {
-            Packaging.ZipPackagePart part = _zipPackage.GetPart(uri);
-            if (Workbook.VbaProject == null)
-            {
-                if (part.ContentType != ContentTypes.contentTypeWorkbookDefault)
-                {
-                    part = _zipPackage.CreatePart(uri, ContentTypes.contentTypeWorkbookDefault, Compression);
-                }
-            }
-            else
-            {
-                if (part.ContentType != ContentTypes.contentTypeWorkbookMacroEnabled)
-                {
-                    var rels = part.GetRelationships();
-                    _zipPackage.DeletePart(uri);
-                    part = ZipPackage.CreatePart(uri, ContentTypes.contentTypeWorkbookMacroEnabled);
-                    foreach (ZipPackageRelationship rel in rels)
-                    {
-                        ZipPackage.DeleteRelationship(rel.Id);
-                        part.CreateRelationship(rel.TargetUri, rel.TargetMode, rel.RelationshipType);
-                    }
-                }
-            }
-            var stream = part.GetStream(FileMode.Create, FileAccess.Write);
-            xmlDoc.Save(stream);
-        }
-
         #endregion
 
         #region Dispose
@@ -1210,6 +1179,49 @@ public CompressionLevel Compression
                 ZipPackage.Compression = value;
             }
         }
+
+        private eDocumentFormat? _format = null;
+
+        /// <summary>
+        /// Gets or sets the file format used when the package is saved.
+        /// <para>
+        /// When a package is loaded, this property is derived from the content type of the 
+        /// workbook part, so a file opened as a template (.xltx/.xltm) reports 
+        /// <see cref="OfficeOpenXml.eDocumentFormat.Template"/>. 
+        /// <see cref="OfficeOpenXml.eDocumentFormat.Workbook"/>.
+        /// </para>
+        /// <para>
+        /// Setting this property overrides the derived value, allowing a loaded template to be 
+        /// saved as a workbook or vice versa. Whether the workbook is saved as a macro-enabled 
+        /// file is determined automatically by the presence of a VBA project.
+        /// </para>
+        /// </summary>
+        public eDocumentFormat DocumentFormat
+        {
+            get
+            {
+                if (_format == null)
+                {
+                    _format = ResolveFormatFromPackage();
+                }
+                return _format.Value;
+            }
+            set
+            {
+                _format = value;
+            }
+        }
+
+        private eDocumentFormat ResolveFormatFromPackage()
+        {            
+            if (_zipPackage == null) return eDocumentFormat.Workbook;
+
+            var wbPart = _zipPackage.GetPartByContentType(ContentTypes.contentTypeTemplateDefault)
+                      ?? _zipPackage.GetPartByContentType(ContentTypes.contentTypeTemplateMacroEnabled);
+
+            return wbPart != null ? eDocumentFormat.Template : eDocumentFormat.Workbook;
+        }
+
         CompatibilitySettings _compatibility = null;
         /// <summary>
         /// Compatibility settings for older versions of EPPlus.

src/EPPlus/ExcelWorkbook.cs

@@ -1559,21 +1559,15 @@ internal void Save()  // Workbook Save
             SetXmlNodeBool("d:calcPr/@fullPrecision", FullPrecision, false);
 
             if(_workbookCreatedInEPPlus == false) EnsureCalculationFeatures();    //Ensure that the calculation features are included in the file to make sure that new functions are supported.
-
-            if (_vba == null && !_package.ZipPackage.PartExists(new Uri(ExcelVbaProject.PartUri, UriKind.Relative)))
+
+            bool isMacroEnabled = !(_vba == null &&
+            !_package.ZipPackage.PartExists(new Uri(ExcelVbaProject.PartUri, UriKind.Relative)));
+
+            var targetContentType = GetWorkbookContentType(_package.DocumentFormat, isMacroEnabled);
+
+            if (Part.ContentType != targetContentType)
             {
-                if (Part.ContentType != ContentTypes.contentTypeWorkbookDefault &&
-                    Part.ContentType != ContentTypes.contentTypeWorkbookMacroEnabled)
-                {
-                    Part.ContentType = ContentTypes.contentTypeWorkbookDefault;
-                }
-            }
-            else
-            {
-                if (Part.ContentType != ContentTypes.contentTypeWorkbookMacroEnabled)
-                {
-                    Part.ContentType = ContentTypes.contentTypeWorkbookMacroEnabled;
-                }
+                Part.ContentType = targetContentType;
             }
 
             UpdateDefinedNamesXml();
@@ -1705,6 +1699,22 @@ internal void Save()  // Workbook Save
             }
         }
 
+        internal string GetWorkbookContentType(eDocumentFormat format, bool isMacroEnabled)
+        {
+            if (format == eDocumentFormat.Template)
+            {
+                return isMacroEnabled
+                    ? ContentTypes.contentTypeTemplateMacroEnabled
+                    : ContentTypes.contentTypeTemplateDefault;
+            }
+            else
+            {
+                return isMacroEnabled
+                    ? ContentTypes.contentTypeWorkbookMacroEnabled
+                    : ContentTypes.contentTypeWorkbookDefault;
+            }
+        }
+
         private void HandleLicense()
         {
             switch (ExcelPackage.License.LicenseType)

src/EPPlus/Packaging/ZipPackage.cs

@@ -534,7 +534,9 @@ internal void Save(Stream stream)
                     part.ContentType == ContentTypes.contentTypeRichDataValueStructure ||
                     part.ContentType == ContentTypes.contentTypeRichDataValue ||
                     part.ContentType == ContentTypes.contentTypeWorkbookDefault ||
-                    part.ContentType == ContentTypes.contentTypeWorkbookMacroEnabled)
+                    part.ContentType == ContentTypes.contentTypeWorkbookMacroEnabled ||
+                    part.ContentType == ContentTypes.contentTypeTemplateDefault ||      // nytt
+                    part.ContentType == ContentTypes.contentTypeTemplateMacroEnabled)   // nytt)
                 {
                     saveAfterParts.Add(part);
                 }

src/EPPlusTest/ExcelPackageTests.cs

@@ -26,6 +26,8 @@ Date               Author                       Change
  *******************************************************************************
   01/27/2020         EPPlus Software AB       Initial release EPPlus 5
  *******************************************************************************/
+using EPPlusTest.Drawing.Chart.Styling;
+using FakeItEasy.Configuration;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using OfficeOpenXml;
 using System;
@@ -37,7 +39,7 @@ Date               Author                       Change
 namespace EPPlusTest
 {
     [TestClass]
-    public class ExcelPackageTests
+    public class ExcelPackageTests : TestBase
     {
         [TestMethod, Ignore]
         public void ConstructorWithStringPath()
@@ -87,5 +89,54 @@ public void ShouldEncryptAndDecryptPackage(EncryptionAlgorithm algorithm)
                 }
             }
         }
+
+        [TestMethod]
+        public void SaveAsTemplate_Debug()
+        {
+            using (var package = new ExcelPackage())
+            {
+                var ws = package.Workbook.Worksheets.Add("Sheet1");
+                ws.Cells["A1"].Value = "Test";
+
+                package.DocumentFormat = eDocumentFormat.Template;
+                SaveAndCleanup(package);
+            }
+        }
+
+        [TestMethod]
+        public void SaveAsTemplate_WithVba_SetsTemplateMacroEnabledContentType()
+        {
+            using (var package = new ExcelPackage())
+            {
+                var ws = package.Workbook.Worksheets.Add("Sheet1");
+                ws.Cells["A1"].Value = "Test";
+
+                package.Workbook.CreateVBAProject();  
+                package.DocumentFormat = eDocumentFormat.Template;
+                SaveAndCleanup(package);
+            }
+        }
+
+        [TestMethod]
+        public void ReadAndConvertToTemplate()
+        {
+            using (var package = OpenTemplatePackage("ExcelTemplateTest.xltx"))
+            {
+                Assert.AreEqual(eDocumentFormat.Template, package.DocumentFormat);                
+                package.DocumentFormat = eDocumentFormat.Workbook;
+                SaveAndCleanup(package);
+            }
+        }
+
+        [TestMethod]
+        public void ReadAndConvertWorkbookToTemplate()
+        {
+            using (var package = OpenTemplatePackage("ExcelTemplateTest.xlsx"))
+            {
+                Assert.AreEqual(eDocumentFormat.Workbook, package.DocumentFormat);
+                package.DocumentFormat = eDocumentFormat.Template;
+                SaveAndCleanup(package);
+            }
+        }
     }
 }