mcs/class/System.Data/System.Data/XmlDataLoader.cs

   1 //
   2 // mcs/class/System.Data/System.Data/XmlDataLoader.cs
   3 //
   4 // Purpose: Loads XmlDocument to DataSet
   5 //
   6 // class: XmlDataLoader
   7 // assembly: System.Data.dll
   8 // namespace: System.Data
   9 //
  10 // Author:
  11 //     Ville Palo <vi64pa@koti.soon.fi>
  12 //
  13 // (c)copyright 2002 Ville Palo
  14 //
  15 // XmlDataLoader is included within the Mono Class Library.
  16 //
  17
  18 using System;
  19 using System.Data;
  20 using System.Xml;
  21 using System.Xml.XPath;
  22 using System.Collections;
  23 using System.Globalization;
  24
  25 namespace System.Data
  26 {
  27
  28         internal class XmlDataLoader
  29         {
  30
  31                 private DataSet DSet;
  32                 Hashtable DiffGrRows = new Hashtable ();
  33
  34                 public XmlDataLoader (DataSet set)
  35                 {
  36                         DSet = set;
  37                 }
  38
  39                 public XmlReadMode LoadData (XmlReader reader, XmlReadMode mode)
  40                 {
  41                         XmlReadMode Result = XmlReadMode.Auto;
  42
  43                         switch (mode) {
  44
  45                                 case XmlReadMode.Fragment:
  46                                         break;
  47                                 case XmlReadMode.ReadSchema:
  48                                 case XmlReadMode.IgnoreSchema:
  49                                 case XmlReadMode.InferSchema:
  50                                         Result = mode;
  51                                         ReadModeSchema (reader, mode);
  52                                         break;
  53                                 default:
  54                                         break;
  55                         }
  56
  57                         return Result;
  58                 }
  59
  60                 #region reading
  61
  62                 // Read information from the reader.
  63                 private void ReadModeSchema (XmlReader reader, XmlReadMode mode)
  64                 {
  65                         bool inferSchema = mode == XmlReadMode.InferSchema ? true : false;
  66                         //check if the current element is schema.
  67                         if (String.Compare (reader.LocalName, "schema", true) == 0) {
  68
  69                                 if (mode == XmlReadMode.InferSchema || mode == XmlReadMode.IgnoreSchema)
  70                                         reader.Skip(); // skip the schema node.
  71                                 else
  72                                         DSet.ReadXmlSchema(reader);
  73
  74                                 reader.MoveToContent();
  75                         }
  76                         // load an XmlDocument from the reader.
  77                         XmlDocument doc = BuildXmlDocument(reader);
  78
  79                         // treatment for .net compliancy :
  80                         // if xml representing dataset has exactly depth of 2 elements,
  81                         // than the root element actually represents datatable and not dataset
  82                         // so we add new root element to doc
  83                         // in order to create an element representing dataset.
  84                         int rootNodeDepth = XmlNodeElementsDepth(doc.DocumentElement);
  85                         if (rootNodeDepth == 2) {
  86                                 // new dataset name
  87                                 String newDataSetName = "NewDataSet";
  88                                 // create new document
  89                                 XmlDocument newDoc = new XmlDocument();
  90                                 // create element for dataset
  91                                 XmlElement datasetElement = newDoc.CreateElement(newDataSetName);
  92                                 // make the new created element to be the new doc root
  93                                 newDoc.AppendChild(datasetElement);
  94                                 // import all the elements from doc and insert them into new doc
  95                                 XmlNode root = newDoc.ImportNode(doc.DocumentElement,true);
  96                                 datasetElement.AppendChild(root);
  97                                 doc = newDoc;
  98                                 // update dataset name
  99                                 DSet.DataSetName = newDataSetName;
 100                         }
 101
 102                         // set EnforceConstraint to false - we do not want any validation during
 103                         // load time.
 104                         bool origEnforceConstraint = DSet.EnforceConstraints;
 105                         DSet.EnforceConstraints = false;
 106
 107                         // The childs are tables.
 108                         XmlNodeList nList = doc.DocumentElement.ChildNodes;
 109
 110                         for (int i = 0; i < nList.Count; i++) {
 111                                 XmlNode node = nList[i];
 112                                 // node represents a table onky if it is of type XmlNodeType.Element
 113                                 if (node.NodeType == XmlNodeType.Element) {
 114                                         AddRowToTable(node, null, inferSchema);
 115                                 }
 116                         }
 117
 118                         // set the EnforceConstraints to original value;
 119                         DSet.EnforceConstraints = origEnforceConstraint;
 120                 }
 121
 122                 #endregion // reading
 123
 124                 #region Private helper methods
 125
 126                 private void ReadColumns (XmlReader reader, DataRow row, DataTable table, string TableName)
 127                 {
 128                         do {
 129                                 if (reader.NodeType == XmlNodeType.Element) {
 130                                         DataColumn col = table.Columns [reader.LocalName];
 131                                         if (col != null) {
 132                                                 row [col] = StringToObject (col.DataType, reader.Value);
 133                                         }
 134                                         reader.Read ();
 135                                 }
 136                                 else {
 137                                         reader.Read ();
 138                                 }
 139
 140                         } while (table.TableName != reader.LocalName
 141                                 || reader.NodeType != XmlNodeType.EndElement);
 142                 }
 143
 144                 internal static object StringToObject (Type type, string value)
 145                 {
 146                         if (type == null) return value;
 147
 148                         switch (Type.GetTypeCode (type)) {
 149                                 case TypeCode.Boolean: return XmlConvert.ToBoolean (value);
 150                                 case TypeCode.Byte: return XmlConvert.ToByte (value);
 151                                 case TypeCode.Char: return (char)XmlConvert.ToInt32 (value);
 152                                 case TypeCode.DateTime: return XmlConvert.ToDateTime (value);
 153                                 case TypeCode.Decimal: return XmlConvert.ToDecimal (value);
 154                                 case TypeCode.Double: return XmlConvert.ToDouble (value);
 155                                 case TypeCode.Int16: return XmlConvert.ToInt16 (value);
 156                                 case TypeCode.Int32: return XmlConvert.ToInt32 (value);
 157                                 case TypeCode.Int64: return XmlConvert.ToInt64 (value);
 158                                 case TypeCode.SByte: return XmlConvert.ToSByte (value);
 159                                 case TypeCode.Single: return XmlConvert.ToSingle (value);
 160                                 case TypeCode.UInt16: return XmlConvert.ToUInt16 (value);
 161                                 case TypeCode.UInt32: return XmlConvert.ToUInt32 (value);
 162                                 case TypeCode.UInt64: return XmlConvert.ToUInt64 (value);
 163                         }
 164
 165                         if (type == typeof (TimeSpan)) return XmlConvert.ToTimeSpan (value);
 166                         if (type == typeof (byte[])) return Convert.FromBase64String (value);
 167
 168                         return Convert.ChangeType (value, type);
 169                 }
 170
 171                 private void AddRowToTable(XmlNode tableNode, DataColumn relationColumn, bool inferSchema)
 172                 {
 173                         Hashtable rowValue = new Hashtable();
 174                         DataTable table;
 175
 176                         // Check if the table exists in the DataSet. If not create one.
 177                         if (DSet.Tables.Contains(tableNode.LocalName))
 178                                 table = DSet.Tables[tableNode.LocalName];
 179                         else if (inferSchema) {
 180                                 table = new DataTable(tableNode.LocalName);
 181                                 DSet.Tables.Add(table);
 182                         }
 183                         else
 184                                 return;
 185
 186                         // For elements that are inferred as tables and that contain text
 187                         // but have no child elements, a new column named "TableName_Text"
 188                         // is created for the text of each of the elements.
 189                         // If an element is inferred as a table and has text, but also has child elements,
 190                         // the text is ignored.
 191                         // Note : if an element is inferred as a table and has text
 192                         // and has no child elements,
 193                         // but the repeated ements of this table have child elements,
 194                         // then the text is ignored.
 195                         if(!HaveChildElements(tableNode) && HaveText(tableNode) &&
 196                                 !IsRepeatedHaveChildNodes(tableNode)) {
 197                                 string columnName = tableNode.Name + "_Text";
 198                                 if (!table.Columns.Contains(columnName)) {
 199                                         table.Columns.Add(columnName);
 200                                 }
 201                                 rowValue.Add(columnName, tableNode.InnerText);
 202                         }
 203
 204                         // Get the child nodes of the table. Any child can be one of the following tow:
 205                         // 1. DataTable - if there was a relation with another table..
 206                         // 2. DataColumn - column of the current table.
 207                         XmlNodeList childList = tableNode.ChildNodes;
 208                         for (int i = 0; i < childList.Count; i++) {
 209                                 XmlNode childNode = childList[i];
 210
 211                                 // we are looping through elements only
 212                                 // Note : if an element is inferred as a table and has text, but also has child elements,
 213                                 // the text is ignored.
 214                                 if (childNode.NodeType != XmlNodeType.Element)
 215                                         continue;
 216
 217                                 // Elements that have attributes are inferred as tables.
 218                                 // Elements that have child elements are inferred as tables.
 219                                 // Elements that repeat are inferred as a single table.
 220                                 if (IsInferedAsTable(childNode)) {
 221                                         // child node infered as table
 222                                         if (inferSchema) {
 223                                                 // We need to create new column for the relation between the current
 224                                                 // table and the new table we found (the child table).
 225                                                 string newRelationColumnName = table.TableName + "_Id";
 226                                                 if (!table.Columns.Contains(newRelationColumnName)) {
 227                                                         DataColumn newRelationColumn = new DataColumn(newRelationColumnName, typeof(int));
 228                                                         newRelationColumn.AutoIncrement = true;
 229                                                         // we do not want to serialize this column so MappingType is Hidden.
 230                                                         newRelationColumn.ColumnMapping = MappingType.Hidden;
 231                                                         table.Columns.Add(newRelationColumn);
 232                                                 }
 233                                                 // Add a row to the new table we found.
 234                                                 AddRowToTable(childNode, table.Columns[newRelationColumnName], inferSchema);
 235                                         }
 236                                         else
 237                                                 AddRowToTable(childNode, null, inferSchema);
 238
 239                                 }
 240                                 else {
 241                                         // Elements that have no attributes or child elements, and do not repeat,
 242                                         // are inferred as columns.
 243                                         object val = null;
 244                                         if (childNode.FirstChild != null)
 245                                                 val = childNode.FirstChild.Value;
 246                                         else
 247                                                 val = "";
 248                                         if (table.Columns.Contains(childNode.LocalName))
 249                                                 rowValue.Add(childNode.LocalName, val);
 250                                         else if (inferSchema) {
 251                                                 table.Columns.Add(childNode.LocalName);
 252                                                 rowValue.Add(childNode.LocalName, val);
 253                                         }
 254                                 }
 255
 256                         }
 257
 258                         // Column can be attribute of the table element.
 259                         XmlAttributeCollection aCollection = tableNode.Attributes;
 260                         for (int i = 0; i < aCollection.Count; i++) {
 261                                 XmlAttribute attr = aCollection[i];
 262                                 //the atrribute can be the namespace.
 263                                 if (attr.Prefix.Equals("xmlns"))
 264                                         table.Namespace = attr.Value;
 265                                 else { // the attribute is a column.
 266                                         if (!table.Columns.Contains(attr.LocalName))
 267                                                 table.Columns.Add(attr.LocalName);
 268                                         table.Columns[attr.LocalName].Namespace = table.Namespace;
 269
 270                                         rowValue.Add(attr.LocalName, attr.Value);
 271                                 }
 272                         }
 273
 274                         // If the current table is a child table we need to add a new column for the relation
 275                         // and add a new relation to the DataSet.
 276                         if (relationColumn != null) {
 277                                 if (!table.Columns.Contains(relationColumn.ColumnName)) {
 278                                         DataColumn dc = new DataColumn(relationColumn.ColumnName, typeof(int));
 279                                         // we do not want to serialize this column so MappingType is Hidden.
 280                                         dc.ColumnMapping = MappingType.Hidden;
 281                                         table.Columns.Add(dc);
 282                                         // Convention of relation name is: ParentTableName_ChildTableName
 283                                         DataRelation dr = new DataRelation(relationColumn.Table.TableName + "_" + dc.Table.TableName, relationColumn, dc);
 284                                         dr.Nested = true;
 285                                         DSet.Relations.Add(dr);
 286                                 }
 287                                 rowValue.Add (relationColumn.ColumnName, relationColumn.GetAutoIncrementValue());
 288                         }
 289
 290                         // Create new row and add all values to the row.
 291                         // then add it to the table.
 292                         DataRow row = table.NewRow ();
 293
 294                         IDictionaryEnumerator enumerator = rowValue.GetEnumerator ();
 295                         while (enumerator.MoveNext ()) {
 296                                 row [enumerator.Key.ToString ()] = StringToObject (table.Columns[enumerator.Key.ToString ()].DataType, enumerator.Value.ToString ());
 297                         }
 298
 299                         table.Rows.Add (row);
 300
 301                 }
 302
 303                 // bulid the document from the reader.
 304                 private XmlDocument BuildXmlDocument(XmlReader reader)
 305                 {
 306                         XmlDocument doc = new XmlDocument();
 307                         // Create the root element. This is the DataSet element.
 308                         XmlElement dataSetElement = doc.CreateElement(DSet.DataSetName);
 309
 310                         do {
 311                                 XmlNode n = doc.ReadNode (reader);
 312                                 if(n == null) break;
 313                                 // Add the table nodes to the DataSet node.
 314                                 dataSetElement.AppendChild (n);
 315                         } while (reader.IsStartElement());
 316
 317                         // Add the DataSet element to the document.
 318                         doc.AppendChild(dataSetElement);
 319                         return doc;
 320                 }
 321
 322                 // this method calculates the depth of child nodes tree
 323                 // and it counts nodes of type XmlNodeType.Element only
 324                 private static int XmlNodeElementsDepth(XmlNode node)
 325                 {
 326                         int maxDepth = -1;
 327             if ((node != null)) {
 328                                 if  ((node.HasChildNodes) && (node.FirstChild.NodeType == XmlNodeType.Element)) {
 329                                         for (int i=0; i<node.ChildNodes.Count; i++) {
 330                                                 if (node.ChildNodes[i].NodeType == XmlNodeType.Element) {
 331                                                         int childDepth = XmlNodeElementsDepth(node.ChildNodes[i]);
 332                                                         maxDepth = (maxDepth < childDepth) ? childDepth : maxDepth;
 333                                                 }
 334                                         }
 335                                 }
 336                                 else {
 337                                         return 1;
 338                                 }
 339                         }
 340                         else {
 341                                 return -1;
 342                         }
 343
 344                         return (maxDepth + 1);
 345                 }
 346
 347                 private bool HaveChildElements(XmlNode node)
 348                 {
 349                         bool haveChildElements = true;
 350                         if(node.ChildNodes.Count > 0) {
 351                                 foreach(XmlNode childNode in node.ChildNodes) {
 352                                         if (childNode.NodeType != XmlNodeType.Element) {
 353                                                 haveChildElements = false;
 354                                                 break;
 355                                         }
 356                                 }
 357                         }
 358                         else {
 359                                 haveChildElements = false;
 360                         }
 361                         return haveChildElements;
 362                 }
 363
 364                 private bool HaveText(XmlNode node)
 365                 {
 366                         bool haveText = true;
 367                         if(node.ChildNodes.Count > 0) {
 368                                 foreach(XmlNode childNode in node.ChildNodes) {
 369                                         if (childNode.NodeType != XmlNodeType.Text) {
 370                                                 haveText = false;
 371                                                 break;
 372                                         }
 373                                 }
 374                         }
 375                         else {
 376                                 haveText = false;
 377                         }
 378                         return haveText;
 379                 }
 380
 381                 private bool IsRepeat(XmlNode node)
 382                 {
 383                         bool isRepeat = false;
 384                         if(node.ParentNode != null) {
 385                                 foreach(XmlNode childNode in node.ParentNode.ChildNodes) {
 386                                         if(childNode != node && childNode.Name == node.Name) {
 387                                                 isRepeat = true;
 388                                                 break;
 389                                         }
 390                                 }
 391                         }
 392                         return isRepeat;
 393                 }
 394
 395                 private bool HaveAttributes(XmlNode node)
 396                 {
 397                         return (node.Attributes != null && node.Attributes.Count > 0);
 398                 }
 399
 400                 private bool IsInferedAsTable(XmlNode node)
 401                 {
 402                         // Elements that have attributes are inferred as tables.
 403                         // Elements that have child elements are inferred as tables.
 404                         // Elements that repeat are inferred as a single table.
 405                         return (HaveChildElements(node) || HaveAttributes(node) ||
 406                                         IsRepeat(node));
 407                 }
 408
 409                 /// <summary>
 410                 /// Returns true is any node that is repeated node for the node supplied
 411                 /// (i.e. is child node of node's parent, have the same name and is not the node itself)
 412                 /// have child elements
 413                 /// </summary>
 414                 private bool IsRepeatedHaveChildNodes(XmlNode node)
 415                 {
 416                         bool isRepeatedHaveChildElements = false;
 417                         if(node.ParentNode != null) {
 418                                 foreach(XmlNode childNode in node.ParentNode.ChildNodes) {
 419                                         if(childNode != node && childNode.Name == node.Name) {
 420                                                 if (HaveChildElements(childNode)) {
 421                                                         isRepeatedHaveChildElements = true;
 422                                                         break;
 423                                                 }
 424                                         }
 425                                 }
 426                         }
 427                         return isRepeatedHaveChildElements;
 428                 }
 429
 430                 #endregion // Private helper methods
 431
 432
 433         }
 434
 435 }