Save as XML feature added (#684)

Similar approach used like Save as JSON or Save as CSV.

src/Microsoft.SqlTools.ServiceLayer/QueryExecution/DataStorage/SaveAsXmlFileStreamFactory.cs

@@ -0,0 +1,71 @@
+// 
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+using System;
+using System.IO;
+using Microsoft.SqlTools.ServiceLayer.QueryExecution.Contracts;
+using Microsoft.SqlTools.ServiceLayer.SqlContext;
+using Microsoft.SqlTools.ServiceLayer.Utility;
+
+namespace Microsoft.SqlTools.ServiceLayer.QueryExecution.DataStorage
+{
+    public class SaveAsXmlFileStreamFactory : IFileStreamFactory
+    {
+
+        #region Properties
+
+        /// <summary>
+        /// Settings for query execution
+        /// </summary>
+        public QueryExecutionSettings QueryExecutionSettings { get; set; }
+
+        /// <summary>
+        /// Parameters for the save as XML request
+        /// </summary>
+        public SaveResultsAsXmlRequestParams SaveRequestParams { get; set; }
+
+        #endregion
+
+        /// <summary>
+        /// File names are not meant to be created with this factory.
+        /// </summary>
+        /// <exception cref="NotImplementedException">Thrown all times</exception>
+        [Obsolete]
+        public string CreateFile()
+        {
+            throw new InvalidOperationException();
+        }
+
+        /// <summary>
+        /// Returns a new service buffer reader for reading results back in from the temporary buffer files
+        /// </summary>
+        /// <param name="fileName">Path to the temp buffer file</param>
+        /// <returns>Stream reader</returns>
+        public IFileStreamReader GetReader(string fileName)
+        {
+            return new ServiceBufferFileStreamReader(new FileStream(fileName, FileMode.Open, FileAccess.Read), QueryExecutionSettings);
+        }
+
+        /// <summary>
+        /// Returns a new XML writer for writing results to a XML file
+        /// </summary>
+        /// <param name="fileName">Path to the XML output file</param>
+        /// <returns>Stream writer</returns>
+        public IFileStreamWriter GetWriter(string fileName)
+        {
+            return new SaveAsXmlFileStreamWriter(new FileStream(fileName, FileMode.Create, FileAccess.ReadWrite), SaveRequestParams);
+        }
+
+        /// <summary>
+        /// Safely deletes the file
+        /// </summary>
+        /// <param name="fileName">Path to the file to delete</param>
+        public void DisposeFile(string fileName)
+        {
+            FileUtilities.SafeFileDelete(fileName);
+        }
+
+    }
+}

src/Microsoft.SqlTools.ServiceLayer/QueryExecution/DataStorage/SaveAsXmlFileStreamWriter.cs

@@ -0,0 +1,142 @@
+// 
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Text;
+using System.Xml;
+using Microsoft.SqlTools.ServiceLayer.QueryExecution.Contracts;
+
+namespace Microsoft.SqlTools.ServiceLayer.QueryExecution.DataStorage
+{
+    /// <summary>
+    /// Writer for writing rows of results to a XML file.
+    /// </summary>
+    /// <remarks>
+    /// This implements its own IDisposable because the cleanup logic closes the element that was
+    /// created when the writer was created. Since this behavior is different than the standard
+    /// file stream cleanup, the extra Dispose method was added.
+    /// </remarks>
+    public class SaveAsXmlFileStreamWriter : SaveAsStreamWriter, IDisposable
+    {
+        // Root element name for the output XML
+        private const string RootElementTag = "data";
+        
+        // Item element name which will be used for every row
+        private const string ItemElementTag = "row";
+        
+        #region Member Variables
+
+        private readonly XmlTextWriter xmlTextWriter;
+
+        #endregion
+
+        /// <summary>
+        /// Constructor, writes the header to the file, chains into the base constructor
+        /// </summary>
+        /// <param name="stream">FileStream to access the JSON file output</param>
+        /// <param name="requestParams">XML save as request parameters</param>
+        public SaveAsXmlFileStreamWriter(Stream stream, SaveResultsAsXmlRequestParams requestParams)
+            : base(stream, requestParams)
+        {
+            // Setup the internal state
+            var encoding = GetEncoding(requestParams);
+            xmlTextWriter = new XmlTextWriter(stream, encoding);
+            xmlTextWriter.Formatting = requestParams.Formatted ? Formatting.Indented : Formatting.None;
+
+            //Start the document and the root element
+            xmlTextWriter.WriteStartDocument();
+            xmlTextWriter.WriteStartElement(RootElementTag);
+        }
+
+        /// <summary>
+        /// Writes a row of data as a XML object
+        /// </summary>
+        /// <param name="row">The data of the row to output to the file</param>
+        /// <param name="columns">
+        /// The entire list of columns for the result set. They will be filtered down as per the
+        /// request params.
+        /// </param>
+        public override void WriteRow(IList<DbCellValue> row, IList<DbColumnWrapper> columns)
+        {
+            // Write the header for the object
+            xmlTextWriter.WriteStartElement(ItemElementTag);
+
+            // Write the items out as properties
+            int columnStart = ColumnStartIndex ?? 0;
+            int columnEnd = ColumnEndIndex + 1 ?? columns.Count;
+            for (int i = columnStart; i < columnEnd; i++)
+            {
+                // Write the column name as item tag
+                xmlTextWriter.WriteStartElement(columns[i].ColumnName);
+                
+                if (row[i].RawObject != null)
+                {
+                    xmlTextWriter.WriteString(row[i].DisplayValue);
+                }
+
+                // End the item tag
+                xmlTextWriter.WriteEndElement();
+            }
+
+            // Write the footer for the object
+            xmlTextWriter.WriteEndElement();
+        }
+
+        /// <summary>
+        /// Get the encoding for the XML file according to <param name="requestParams"></param>
+        /// </summary>
+        /// <param name="requestParams">XML save as request parameters</param>
+        /// <returns></returns>
+        private Encoding GetEncoding(SaveResultsAsXmlRequestParams requestParams)
+        {
+            Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);
+            Encoding encoding;
+            try
+            {
+                if (int.TryParse(requestParams.Encoding, out var codepage))
+                {
+                    encoding = Encoding.GetEncoding(codepage);
+                }
+                else
+                {
+                    encoding = Encoding.GetEncoding(requestParams.Encoding);
+                }
+            }
+            catch
+            {
+                // Fallback encoding when specified codepage is invalid
+                encoding = Encoding.GetEncoding("utf-8");
+            }
+
+            return encoding;
+        }
+
+        private bool disposed = false;
+
+        /// <summary>
+        /// Disposes the writer by closing up the element that contains the row objects
+        /// </summary>
+        protected override void Dispose(bool disposing)
+        {
+            if (disposed)
+                return;
+
+            if (disposing)
+            {
+                // Write the footer of the file
+                xmlTextWriter.WriteEndElement();
+                xmlTextWriter.WriteEndDocument();
+
+                xmlTextWriter.Close();
+                xmlTextWriter.Dispose();
+            }
+
+            disposed = true;
+            base.Dispose(disposing);
+        }
+    }
+}