mcs/class/System.Data/System.Data/ForeignKeyConstraint.cs

   1 //
   2 // System.Data.ForeignKeyConstraint.cs
   3 //
   4 // Author:
   5 //   Franklin Wise <gracenote@earthlink.net>
   6 //   Daniel Morgan <danmorg@sc.rr.com>
   7 //
   8 // (C) 2002 Franklin Wise
   9 // (C) 2002 Daniel Morgan
  10 //
  11
  12 //
  13 // Copyright (C) 2004 Novell, Inc (http://www.novell.com)
  14 //
  15 // Permission is hereby granted, free of charge, to any person obtaining
  16 // a copy of this software and associated documentation files (the
  17 // "Software"), to deal in the Software without restriction, including
  18 // without limitation the rights to use, copy, modify, merge, publish,
  19 // distribute, sublicense, and/or sell copies of the Software, and to
  20 // permit persons to whom the Software is furnished to do so, subject to
  21 // the following conditions:
  22 //
  23 // The above copyright notice and this permission notice shall be
  24 // included in all copies or substantial portions of the Software.
  25 //
  26 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  27 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  28 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  29 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  30 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  31 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  32 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  33 //
  34
  35 using System;
  36 using System.Collections;
  37 using System.ComponentModel;
  38 using System.Runtime.InteropServices;
  39 using System.Data.Common;
  40
  41 namespace System.Data {
  42         [Editor ("Microsoft.VSDesigner.Data.Design.ForeignKeyConstraintEditor, " + Consts.AssemblyMicrosoft_VSDesigner,
  43                  "System.Drawing.Design.UITypeEditor, " + Consts.AssemblySystem_Drawing)]
  44         [DefaultProperty ("ConstraintName")]
  45 #if !NET_2_0
  46         [Serializable]
  47 #endif
  48         public class ForeignKeyConstraint : Constraint
  49         {
  50                 private UniqueConstraint _parentUniqueConstraint;
  51                 //FIXME: create a class which will wrap this collection
  52                 private DataColumn [] _parentColumns;
  53                 //FIXME: create a class which will wrap this collection
  54                 private DataColumn [] _childColumns;
  55                 private Rule _deleteRule = Rule.Cascade;
  56                 private Rule _updateRule = Rule.Cascade;
  57                 private AcceptRejectRule _acceptRejectRule = AcceptRejectRule.None;
  58                 private string _parentTableName;
  59                 private string _childTableName;
  60
  61                 //FIXME: remove those; and use only DataColumns[]
  62                 private string [] _parentColumnNames;
  63                 private string [] _childColumnNames;
  64
  65                 #region Constructors
  66
  67                 public ForeignKeyConstraint(DataColumn parentColumn, DataColumn childColumn)
  68                 {
  69                         if (null == parentColumn || null == childColumn) {
  70                                 throw new NullReferenceException("Neither parentColumn or" +
  71                                         " childColumn can be null.");
  72                         }
  73                         _foreignKeyConstraint(null, new DataColumn[] {parentColumn},
  74                                         new DataColumn[] {childColumn});
  75                 }
  76
  77                 public ForeignKeyConstraint(DataColumn[] parentColumns, DataColumn[] childColumns)
  78                 {
  79                         _foreignKeyConstraint(null, parentColumns, childColumns);
  80                 }
  81
  82                 public ForeignKeyConstraint(string constraintName, DataColumn parentColumn, DataColumn childColumn)
  83                 {
  84                         if (null == parentColumn || null == childColumn) {
  85                                 throw new NullReferenceException("Neither parentColumn or" +
  86                                         " childColumn can be null.");
  87                         }
  88
  89                         _foreignKeyConstraint(constraintName, new DataColumn[] {parentColumn},
  90                                         new DataColumn[] {childColumn});
  91                 }
  92
  93                 public ForeignKeyConstraint(string constraintName, DataColumn[] parentColumns, DataColumn[] childColumns)
  94                 {
  95                         _foreignKeyConstraint(constraintName, parentColumns, childColumns);
  96                 }
  97
  98                 //special case
  99                 [Browsable (false)]
 100                 public ForeignKeyConstraint(string constraintName, string parentTableName, string[] parentColumnNames, string[] childColumnNames, AcceptRejectRule acceptRejectRule, Rule deleteRule, Rule updateRule)
 101                 {
 102                         InitInProgress = true;
 103                         base.ConstraintName = constraintName;
 104
 105                         // "parentTableName" is searched in the "DataSet" to which the "DataTable"
 106                         // from which AddRange() is called
 107                         // childTable is the "DataTable" which calls AddRange()
 108
 109                         // Keep reference to parentTableName to resolve later
 110                         _parentTableName = parentTableName;
 111
 112                         // Keep reference to parentColumnNames to resolve later
 113                         _parentColumnNames = parentColumnNames;
 114
 115                         // Keep reference to childColumnNames to resolve later
 116                         _childColumnNames = childColumnNames;
 117
 118                         _acceptRejectRule = acceptRejectRule;
 119                         _deleteRule = deleteRule;
 120                         _updateRule = updateRule;
 121                 }
 122
 123                 internal override void FinishInit (DataTable childTable)
 124                 {
 125                         if (childTable.DataSet == null)
 126                                 throw new InvalidConstraintException ("ChildTable : " + childTable.TableName + " does not belong to any DataSet");
 127
 128                         DataSet dataSet = childTable.DataSet;
 129                         _childTableName = childTable.TableName;
 130
 131                         if (!dataSet.Tables.Contains (_parentTableName))
 132                                 throw new InvalidConstraintException ("Table : " + _parentTableName + "does not exist in DataSet : " + dataSet);
 133
 134                         DataTable parentTable = dataSet.Tables [_parentTableName];
 135
 136                         int i = 0, j = 0;
 137
 138                         if (_parentColumnNames.Length < 0 || _childColumnNames.Length < 0)
 139                                 throw new InvalidConstraintException ("Neither parent nor child columns can be zero length");
 140
 141                         if (_parentColumnNames.Length != _childColumnNames.Length)
 142                                 throw new InvalidConstraintException ("Both parent and child columns must be of same length");
 143                         DataColumn[] parentColumns = new DataColumn [_parentColumnNames.Length];
 144                         DataColumn[] childColumns = new DataColumn [_childColumnNames.Length];
 145
 146                         foreach (string parentCol in _parentColumnNames){
 147                                 if (!parentTable.Columns.Contains (parentCol))
 148                                         throw new InvalidConstraintException ("Table : " + _parentTableName + "does not contain the column :" + parentCol);
 149                                 parentColumns [i++] = parentTable. Columns [parentCol];
 150                         }
 151
 152                         foreach (string childCol in _childColumnNames){
 153                                 if (!childTable.Columns.Contains (childCol))
 154                                         throw new InvalidConstraintException ("Table : " + _childTableName + "does not contain the column : " + childCol);
 155                                 childColumns [j++] = childTable.Columns [childCol];
 156                         }
 157                         _validateColumns (parentColumns, childColumns);
 158                         _parentColumns = parentColumns;
 159                         _childColumns = childColumns;
 160                         InitInProgress = false;
 161                 }
 162
 163 #if NET_2_0
 164                 [MonoTODO]
 165                 public ForeignKeyConstraint (string constraintName, string parentTableName, string parentTableNamespace, string[] parentColumnNames, string[] childColumnNames, AcceptRejectRule acceptRejectRule, Rule deleteRule, Rule updateRule)
 166                 {
 167                         throw new NotImplementedException ();
 168                 }
 169 #endif
 170
 171                 private void _foreignKeyConstraint(string constraintName, DataColumn[] parentColumns,
 172                                 DataColumn[] childColumns)
 173                 {
 174
 175                         //Validate
 176                         _validateColumns(parentColumns, childColumns);
 177
 178                         //Set Constraint Name
 179                         base.ConstraintName = constraintName;
 180
 181                         //Keep reference to columns
 182                         _parentColumns = parentColumns;
 183                         _childColumns = childColumns;
 184                 }
 185
 186 #endregion // Constructors
 187
 188 #region Helpers
 189
 190                 private void _validateColumns(DataColumn[] parentColumns, DataColumn[] childColumns)
 191                 {
 192                         //not null
 193                         if (null == parentColumns || null == childColumns)
 194                                 throw new ArgumentNullException();
 195
 196                         //at least one element in each array
 197                         if (parentColumns.Length < 1 || childColumns.Length < 1)
 198                                 throw new ArgumentException("Neither ParentColumns or ChildColumns can't be" +
 199                                                 " zero length.");
 200
 201                         //same size arrays
 202                         if (parentColumns.Length != childColumns.Length)
 203                                 throw new ArgumentException("Parent columns and child columns must be the same length.");
 204
 205
 206                         DataTable ptable = parentColumns[0].Table;
 207                         DataTable ctable = childColumns[0].Table;
 208
 209                         for (int i = 0; i < parentColumns.Length; i++) {
 210                                 DataColumn pc = parentColumns[i];
 211                                 DataColumn cc = childColumns[i];
 212
 213                                 //not null check
 214                                 if (null == pc.Table)
 215                                         throw new ArgumentException("All columns must belong to a table." +
 216                                                 " ColumnName: " + pc.ColumnName + " does not belong to a table.");
 217
 218                                 //All columns must belong to the same table
 219                                 if (ptable != pc.Table)
 220                                         throw new InvalidConstraintException("Parent columns must all belong to the same table.");
 221
 222                                 //not null check
 223                                 if (null == cc.Table)
 224                                         throw new ArgumentException("All columns must belong to a table." +
 225                                                 " ColumnName: " + pc.ColumnName + " does not belong to a table.");
 226
 227                                 //All columns must belong to the same table.
 228                                 if (ctable != cc.Table)
 229                                         throw new InvalidConstraintException("Child columns must all belong to the same table.");
 230
 231                                 if (pc.CompiledExpression != null)
 232                                         throw new ArgumentException(String.Format("Cannot create a constraint based on Expression column {0}.", pc.ColumnName));
 233
 234                                 if (cc.CompiledExpression != null)
 235                                         throw new ArgumentException(String.Format("Cannot create a constraint based on Expression column {0}.", cc.ColumnName));
 236
 237                         }
 238
 239                         //Same dataset.  If both are null it's ok
 240                         if (ptable.DataSet != ctable.DataSet)
 241                         {
 242                                 //LAMESPEC: spec says InvalidConstraintExceptoin
 243                                 //      impl does InvalidOperationException
 244                                 throw new InvalidOperationException("Parent column and child column must belong to" +
 245                                                 " tables that belong to the same DataSet.");
 246
 247                         }
 248
 249
 250                         for (int i = 0; i < parentColumns.Length; i++)
 251                         {
 252                                 DataColumn pc = parentColumns[i];
 253                                 DataColumn cc = childColumns[i];
 254
 255                                 //Can't be the same column
 256                                 if (pc == cc)
 257                                         throw new InvalidOperationException("Parent and child columns can't be the same column.");
 258
 259                                 if (! pc.DataType.Equals(cc.DataType))
 260                                 {
 261                                         //LAMESPEC: spec says throw InvalidConstraintException
 262                                         //              implementation throws InvalidOperationException
 263                                         throw new InvalidConstraintException("Parent column is not type compatible with it's child"
 264                                                 + " column.");
 265                                 }
 266
 267                         }
 268
 269                 }
 270
 271                 //Checks to see if a related unique constraint exists
 272                 //if it doesn't then a unique constraint is created.
 273                 //if a unique constraint can't be created an exception will be thrown
 274                 private void _ensureUniqueConstraintExists(ConstraintCollection collection,
 275                                 DataColumn [] parentColumns)
 276                 {
 277                         //not null
 278                         if (null == parentColumns) throw new ArgumentNullException(
 279                                         "ParentColumns can't be null");
 280
 281                         UniqueConstraint uc = null;
 282
 283                         //see if unique constraint already exists
 284                         //if not create unique constraint
 285                         if(parentColumns[0] != null)
 286                                 uc = UniqueConstraint.GetUniqueConstraintForColumnSet(parentColumns[0].Table.Constraints, parentColumns);
 287
 288                         if (null == uc) {
 289                                 uc = new UniqueConstraint(parentColumns, false); //could throw
 290                                 parentColumns [0].Table.Constraints.Add (uc);
 291                         }
 292
 293                         //keep reference
 294                         _parentUniqueConstraint = uc;
 295                         _parentUniqueConstraint.ChildConstraint = this;
 296                 }
 297
 298
 299                 #endregion //Helpers
 300
 301                 #region Properties
 302
 303                 [DataCategory ("Data")]
 304 #if !NET_2_0
 305                 [DataSysDescription ("For accept and reject changes, indicates what kind of cascading should take place across this relation.")]
 306 #endif
 307                 [DefaultValue (AcceptRejectRule.None)]
 308                 public virtual AcceptRejectRule AcceptRejectRule {
 309                         get { return _acceptRejectRule; }
 310                         set { _acceptRejectRule = value; }
 311                 }
 312
 313                 [DataCategory ("Data")]
 314 #if !NET_2_0
 315                 [DataSysDescription ("Indicates the child columns of this constraint.")]
 316 #endif
 317                 [ReadOnly (true)]
 318                 public virtual DataColumn[] Columns {
 319                         get { return _childColumns; }
 320                 }
 321
 322                 [DataCategory ("Data")]
 323 #if !NET_2_0
 324                 [DataSysDescription ("For deletions, indicates what kind of cascading should take place across this relation.")]
 325 #endif
 326                 [DefaultValue (Rule.Cascade)]
 327                 public virtual Rule DeleteRule {
 328                         get { return _deleteRule; }
 329                         set { _deleteRule = value; }
 330                 }
 331
 332                 [DataCategory ("Data")]
 333 #if !NET_2_0
 334                 [DataSysDescription ("For updates, indicates what kind of cascading should take place across this relation.")]
 335 #endif
 336                 [DefaultValue (Rule.Cascade)]
 337                 public virtual Rule UpdateRule {
 338                         get { return _updateRule; }
 339                         set { _updateRule = value; }
 340                 }
 341
 342                 [DataCategory ("Data")]
 343 #if !NET_2_0
 344                 [DataSysDescription ("Indicates the parent columns of this constraint.")]
 345 #endif
 346                 [ReadOnly (true)]
 347                 public virtual DataColumn[] RelatedColumns {
 348                         get { return _parentColumns; }
 349                 }
 350
 351                 [DataCategory ("Data")]
 352 #if !NET_2_0
 353                 [DataSysDescription ("Indicates the child table of this constraint.")]
 354 #endif
 355                 [ReadOnly (true)]
 356                 public virtual DataTable RelatedTable {
 357                         get {
 358                                 if (_parentColumns != null)
 359                                         if (_parentColumns.Length > 0)
 360                                                 return _parentColumns[0].Table;
 361
 362                                 throw new InvalidOperationException ("Property not accessible because 'Object reference not set to an instance of an object'");
 363                         }
 364                 }
 365
 366                 [DataCategory ("Data")]
 367 #if !NET_2_0
 368                 [DataSysDescription ("Indicates the table of this constraint.")]
 369 #endif
 370                 [ReadOnly (true)]
 371                 public override DataTable Table {
 372                         get {
 373                                 if (_childColumns != null)
 374                                         if (_childColumns.Length > 0)
 375                                                 return _childColumns[0].Table;
 376
 377                                 throw new InvalidOperationException ("Property not accessible because 'Object reference not set to an instance of an object'");
 378                         }
 379                 }
 380
 381                 internal UniqueConstraint ParentConstraint {
 382                         get { return _parentUniqueConstraint; }
 383                 }
 384
 385                 #endregion // Properties
 386
 387                 #region Methods
 388
 389                 public override bool Equals(object key)
 390                 {
 391                         ForeignKeyConstraint fkc = key as ForeignKeyConstraint;
 392                         if (null == fkc) return false;
 393
 394                         //if the fk constrains the same columns then they are equal
 395                         if (! DataColumn.AreColumnSetsTheSame( this.RelatedColumns, fkc.RelatedColumns))
 396                                 return false;
 397                         if (! DataColumn.AreColumnSetsTheSame( this.Columns, fkc.Columns) )
 398                                 return false;
 399
 400                         return true;
 401                 }
 402
 403                 public override int GetHashCode()
 404                 {
 405                         //initialize hash1 and hash2 with default hashes
 406                         //any two DIFFERENT numbers will do here
 407                         int hash1 = 32, hash2 = 88;
 408                         int i;
 409
 410                         //derive the hash code from the columns that way
 411                         //Equals and GetHashCode return Equal objects to be the
 412                         //same
 413
 414                         //Get the first parent column hash
 415                         if (this.Columns.Length > 0)
 416                                 hash1 ^= this.Columns[0].GetHashCode();
 417
 418                         //get the rest of the parent column hashes if there any
 419                         for (i = 1; i < this.Columns.Length; i++)
 420                         {
 421                                 hash1 ^= this.Columns[1].GetHashCode();
 422
 423                         }
 424
 425                         //Get the child column hash
 426                         if (this.RelatedColumns.Length > 0)
 427                                 hash2 ^= this.Columns[0].GetHashCode();
 428
 429                         for (i = 1; i < this.RelatedColumns.Length; i++)
 430                         {
 431                                 hash2 ^= this.RelatedColumns[1].GetHashCode();
 432                         }
 433
 434                         //combine the two hashes
 435                         return hash1 ^ hash2;
 436                 }
 437
 438                 internal override void AddToConstraintCollectionSetup(
 439                                 ConstraintCollection collection)
 440                 {
 441                         if (collection.Table != Table)
 442                                 throw new InvalidConstraintException("This constraint cannot be added since ForeignKey doesn't belong to table " + RelatedTable.TableName + ".");
 443
 444                         //run Ctor rules again
 445                         _validateColumns(_parentColumns, _childColumns);
 446
 447                         //we must have a unique constraint on the parent
 448                         _ensureUniqueConstraintExists(collection, _parentColumns);
 449
 450                         if ( (Table.DataSet != null && Table.DataSet.EnforceConstraints)
 451                              || (Table.DataSet == null && Table.EnforceConstraints)) {
 452                                 if (IsConstraintViolated())
 453                                         throw new ArgumentException("This constraint cannot be enabled as not all values have corresponding parent values.");
 454                         }
 455                         //FIXME : if this fails and we created a unique constraint
 456                         //we should probably roll it back
 457                         // and remove index form Table
 458                 }
 459
 460                 internal override void RemoveFromConstraintCollectionCleanup(
 461                                 ConstraintCollection collection)
 462                 {
 463                         _parentUniqueConstraint.ChildConstraint = null;
 464                         Index = null;
 465                 }
 466
 467                 internal override bool IsConstraintViolated()
 468                 {
 469                         if (Table.DataSet == null || RelatedTable.DataSet == null)
 470                                 return false;
 471
 472                         bool hasErrors = false;
 473                         foreach (DataRow row in Table.Rows) {
 474                                 // first we check if all values in _childColumns place are nulls.
 475                                 // if yes we return.
 476                                 if (row.IsNullColumns(_childColumns))
 477                                         continue;
 478
 479                                 // check whenever there is (at least one) parent row  in RelatedTable
 480                                 if(!RelatedTable.RowsExist(_parentColumns,_childColumns,row)) {
 481                                         // if no parent row exists - constraint is violated
 482                                         hasErrors = true;
 483                                         string[] values = new string[_childColumns.Length];
 484                                         for (int i = 0; i < _childColumns.Length; i++){
 485                                                 DataColumn col = _childColumns[i];
 486                                                 values[i] = row[col].ToString();
 487                                         }
 488
 489                                         row.RowError = String.Format("ForeignKeyConstraint {0} requires the child key values ({1}) to exist in the parent table.",
 490                                                 ConstraintName, String.Join(",", values));
 491                                 }
 492                         }
 493
 494                         if (hasErrors)
 495                                 //throw new ConstraintException("Failed to enable constraints. One or more rows contain values violating non-null, unique, or foreign-key constraints.");
 496                                 return true;
 497
 498                         return false;
 499                 }
 500
 501                 internal override void AssertConstraint(DataRow row)
 502                 {
 503                         // first we check if all values in _childColumns place are nulls.
 504                         // if yes we return.
 505                         if (row.IsNullColumns(_childColumns))
 506                                 return;
 507
 508                         // check whenever there is (at least one) parent row  in RelatedTable
 509                         if(!RelatedTable.RowsExist(_parentColumns,_childColumns,row)) {
 510                                 // if no parent row exists - constraint is violated
 511                                 throw new InvalidConstraintException(GetErrorMessage(row));
 512                         }
 513                 }
 514
 515                 internal override bool IsColumnContained(DataColumn column)
 516                 {
 517                         for (int i = 0; i < _parentColumns.Length; i++)
 518                                 if (column == _parentColumns[i])
 519                                         return true;
 520
 521                         for (int i = 0; i < _childColumns.Length; i++)
 522                                 if (column == _childColumns[i])
 523                                         return true;
 524
 525                         return false;
 526                 }
 527
 528                 internal override bool CanRemoveFromCollection(ConstraintCollection col, bool shouldThrow){
 529                         return true;
 530                 }
 531
 532                 private string GetErrorMessage(DataRow row)
 533                 {
 534                         System.Text.StringBuilder sb = new System.Text.StringBuilder();
 535                         for (int i = 0; i < _childColumns.Length; i++) {
 536                                 sb.Append(row[_childColumns[0]].ToString());
 537                                 if (i != _childColumns.Length - 1) {
 538                                         sb.Append(',');
 539                                 }
 540                         }
 541                         string valStr = sb.ToString();
 542                         return "ForeignKeyConstraint " + ConstraintName + " requires the child key values (" + valStr + ") to exist in the parent table.";
 543                 }
 544
 545                 #endregion // Methods
 546         }
 547
 548 }