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

src/EPPlus/Configuration/EPPlusSaveOption.cs

@@ -0,0 +1,27 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace OfficeOpenXml.Configuration
+{
+    /// <summary>
+    /// Options used when saving an <see cref="ExcelPackage"/>.
+    /// Supplied via an action to the Save and SaveAs methods.
+    /// </summary>
+    public class EPPlusSaveOption
+    {
+        /// <summary>
+        /// The password to encrypt the workbook with. 
+        /// This overrides the Encryption.Password on the package. 
+        /// If null, the password set on the package is used.
+        /// </summary>
+        public string Password { get; set; } = null;
+
+        /// <summary>
+        /// If true, the package is saved as an Excel template (.xltx, or .xltm if the workbook 
+        /// contains a VBA project) instead of a standard workbook. Default is false.
+        /// </summary>
+        public bool SaveAsTemplate { get; set; } = false;
+    }
+}

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/ExcelPackage.cs

@@ -881,39 +881,6 @@ 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
@@ -1096,6 +1063,21 @@ public void Save(string password)
             Save();
         }
         /// <summary>
+        /// Saves all the components back into the package.
+        /// This method recursively calls the Save method on all sub-components.
+        /// The package is closed after it has been saved
+        /// </summary>
+        /// <param name="options">An action used to configure the save options, for example saving the package as an Excel template.</param>
+        public void Save(Action<EPPlusSaveOption> options)
+        {
+            var o = new EPPlusSaveOption();
+            options.Invoke(o);
+
+            Encryption.Password = o.Password;
+            SaveAsTemplate = o.SaveAsTemplate;
+            Save();
+        }
+        /// <summary>
         /// Saves the workbook to a new file
         /// The package is closed after it has been saved        
         /// </summary>
@@ -1165,7 +1147,52 @@ public void SaveAs(Stream OutputStream, string password)
             Encryption.Password = password;
             SaveAs(OutputStream);
         }
+        /// <summary>
+        /// Saves the workbook to a new file
+        /// The package is closed after it has been saved
+        /// </summary>
+        /// <param name="filePath">The file location</param>
+        /// <param name="options">An action used to configure the save options, for example saving the package as an Excel template.</param>
+        public void SaveAs(string filePath, Action<EPPlusSaveOption> options)
+        {
+            var o = new EPPlusSaveOption();
+            options.Invoke(o);
+
+            Encryption.Password = o.Password;
+            SaveAsTemplate = o.SaveAsTemplate;
+
+            SaveAs(new FileInfo(filePath)); 
+        }
+        /// <summary>
+        /// Saves the workbook to a new file
+        /// The package is closed after it has been saved
+        /// </summary>
+        /// <param name="file">The file</param>
+        /// <param name="options">An action used to configure the save options, for example saving the package as an Excel template.</param>
+        public void SaveAs(FileInfo file, Action<EPPlusSaveOption> options)
+        {
+            var o = new EPPlusSaveOption();
+            options.Invoke(o);
 
+            File = file;
+            Encryption.Password = o.Password;
+            SaveAsTemplate = o.SaveAsTemplate;
+            Save();
+        }
+        /// <summary>
+        /// Copies the Package to the Outstream
+        /// The package is closed after it has been saved
+        /// </summary>
+        /// <param name="OutputStream">The stream to copy the package to</param>
+        /// <param name="options">An action used to configure the save options, for example saving the package as an Excel template.</param>
+        public void SaveAs(Stream OutputStream, Action<EPPlusSaveOption> options)
+        {
+            var o = new EPPlusSaveOption();
+            options.Invoke(o);
+            Encryption.Password = o.Password;
+            SaveAsTemplate = o.SaveAsTemplate;
+            SaveAs(OutputStream);
+        }
         /// <summary>
         /// The output file. Null if no file is used
         /// </summary>
@@ -1210,6 +1237,19 @@ public CompressionLevel Compression
                 ZipPackage.Compression = value;
             }
         }
+
+        /// <summary>
+        /// If true, the package is saved as an Excel template (.xltx, or .xltm if the workbook 
+        /// contains a VBA project). If false, it is saved as a standard Excel workbook 
+        /// (.xlsx/.xlsm). Default is false.
+        /// </summary>
+        /// <remarks>
+        /// This value is not derived from a loaded package, so a template that is loaded and saved 
+        /// again becomes a standard workbook unless this is set to true. This mirrors how Excel 
+        /// handles templates.
+        /// </remarks>
+        public bool SaveAsTemplate { get; set; } = false;   
+
         CompatibilitySettings _compatibility = null;
         /// <summary>
         /// Compatibility settings for older versions of EPPlus.

src/EPPlus/ExcelPackageAsync.cs

@@ -16,7 +16,10 @@ Date               Author                       Change
 using System;
 using System.IO;
 using OfficeOpenXml.Utils.FileUtils;
-
+using OfficeOpenXml.FormulaParsing.Excel.Functions.Finance.FinancialDayCount;
+using OfficeOpenXml.Configuration;
+using System.Runtime.CompilerServices;
+using System.Security.Cryptography;
 #if !NET35 && !NET40
 using System.Threading;
 using System.Threading.Tasks;
@@ -335,6 +338,24 @@ public async Task SaveAsync(string password, CancellationToken cancellationToken
             await SaveAsync(cancellationToken).ConfigureAwait(false);
         }
 
+        /// <summary>
+        /// Saves all the components back into the package asynchronously.
+        /// This method recursively calls the Save method on all sub-components.
+        /// The package is closed after it has been saved.
+        /// Supply a password to encrypt the workbook with.
+        /// </summary>
+        /// <param name="options">An action used to configure the save options, for example saving the package as an Excel template.</param>
+        /// <param name="cancellationToken">The cancellation token.</param>
+        /// <returns>A task that represents the asynchronous save operation.</returns>
+        public async Task SaveAsync(Action<EPPlusSaveOption> options, CancellationToken cancellationToken = default)
+        {
+            var o = new EPPlusSaveOption();
+            options.Invoke(o);
+            Encryption.Password = o.Password;
+            SaveAsTemplate = o.SaveAsTemplate;
+            await SaveAsync(cancellationToken).ConfigureAwait(false);
+        }
+
         #endregion
 
         #region SaveAsAsync
@@ -361,6 +382,22 @@ public async Task SaveAsAsync(string filePath, CancellationToken cancellationTok
             await SaveAsAsync(new FileInfo(filePath), cancellationToken);
         }
 
+        /// <summary>
+        /// Saves the workbook to a new file
+        /// The package is closed after it has been saved
+        /// </summary>
+        /// <param name="filePath">The file location</param>
+        /// <param name="options">An action used to configure the save options, for example saving the package as an Excel template.</param>
+        /// <param name="cancellationToken">The cancellation token</param>
+        public async Task SaveAsAsync(string filePath, Action<EPPlusSaveOption> options, CancellationToken cancellationToken = default)
+        {
+            var o = new EPPlusSaveOption();
+            options.Invoke(o);
+            Encryption.Password = o.Password;
+            SaveAsTemplate = o.SaveAsTemplate;
+            await SaveAsAsync(new FileInfo(filePath), cancellationToken);
+        }
+
         /// <summary>
         /// Saves the workbook to a new file
         /// The package is closed after it has been saved
@@ -375,6 +412,23 @@ public async Task SaveAsAsync(FileInfo file, string password, CancellationToken
             Encryption.Password = password;
             await SaveAsync(cancellationToken).ConfigureAwait(false);
         }
+
+        /// <summary>
+        /// Saves the workbook to a new file
+        /// The package is closed after it has been saved
+        /// </summary>
+        /// <param name="file">The file</param>
+        /// <param name="options">An action used to configure the save options, for example saving the package as an Excel template.</param>
+        /// <param name="cancellationToken">The cancellation token</param>
+        public async Task SaveAsAsync(FileInfo file, Action<EPPlusSaveOption> options, CancellationToken cancellationToken = default)
+        {
+            var o = new EPPlusSaveOption();
+            options.Invoke(o);
+            File = file;
+            Encryption.Password = o.Password;
+            SaveAsTemplate = o.SaveAsTemplate;
+            await SaveAsync(cancellationToken).ConfigureAwait(false);
+        }
         /// <summary>
         /// Saves the workbook to a new file
         /// The package is closed after it has been saved
@@ -404,6 +458,27 @@ public async Task SaveAsAsync(Stream OutputStream, CancellationToken cancellatio
                 await StreamUtil.CopyStreamAsync(_stream, OutputStream, cancellationToken).ConfigureAwait(false);
             }
         }
+        /// <summary>
+        /// Copies the Package to the Outstream
+        /// The package is closed after it has been saved
+        /// </summary>
+        /// <param name="OutputStream">The stream to copy the package to</param>
+        /// <param name="options">An action used to configure the save options, for example saving the package as an Excel template.</param>
+        /// <param name="cancellationToken">The cancellation token</param>
+        public async Task SaveAsAsync(Stream OutputStream, Action<EPPlusSaveOption> options, CancellationToken cancellationToken = default)
+        {
+            var o = new EPPlusSaveOption();
+            options.Invoke(o);
+            SaveAsTemplate = o.SaveAsTemplate;
+            Encryption.Password = o.Password;
+            File = null;
+            await SaveAsync(cancellationToken).ConfigureAwait(false);
+
+            if (OutputStream != _stream)
+            {
+                await StreamUtil.CopyStreamAsync(_stream, OutputStream, cancellationToken).ConfigureAwait(false);
+            }
+        }
 
         /// <summary>
         /// Copies the Package to the Outstream

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.SaveAsTemplate, 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(bool saveAsTemplate, bool isMacroEnabled)
+        {
+            if (saveAsTemplate)
+            {
+                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 ||      
+                    part.ContentType == ContentTypes.contentTypeTemplateMacroEnabled)   
                 {
                     saveAfterParts.Add(part);
                 }