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                 //FIXME: remove those; and use only DataColumns[]
  61         private string [] _parentColumnNames;
  62         private string [] _childColumnNames;
  63         private bool _dataColsNotValidated = false;
  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                         _dataColsNotValidated = 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
 124                 internal void postAddRange (DataTable childTable)
 125         {
 126             // LAMESPEC - Does not say that this is mandatory
 127             // Check whether childTable belongs to a DataSet
 128             if (childTable.DataSet == null)
 129                     throw new InvalidConstraintException ("ChildTable : " + childTable.TableName + " does not belong to any DataSet");
 130             DataSet dataSet = childTable.DataSet;
 131             _childTableName = childTable.TableName;
 132             // Search for the parentTable in the childTable's DataSet
 133             if (!dataSet.Tables.Contains (_parentTableName))
 134                     throw new InvalidConstraintException ("Table : " + _parentTableName + "does not exist in DataSet : " + dataSet);
 135
 136             // Keep reference to parentTable
 137             DataTable parentTable = dataSet.Tables [_parentTableName];
 138
 139             int i = 0, j = 0;
 140
 141             // LAMESPEC - Does not say which Exception is thrown
 142             if (_parentColumnNames.Length < 0 || _childColumnNames.Length < 0)
 143                     throw new InvalidConstraintException ("Neither parent nor child columns can be zero length");
 144             // LAMESPEC - Does not say which Exception is thrown
 145             if (_parentColumnNames.Length != _childColumnNames.Length)
 146                                 throw new InvalidConstraintException ("Both parent and child columns must be of same length");
 147             DataColumn []parentColumns = new DataColumn [_parentColumnNames.Length];
 148             DataColumn []childColumns = new DataColumn [_childColumnNames.Length];
 149
 150             // Search for the parentColumns in parentTable
 151             foreach (string parentCol in _parentColumnNames){
 152                     if (!parentTable.Columns.Contains (parentCol))
 153                             throw new InvalidConstraintException ("Table : " + _parentTableName + "does not contain the column :" + parentCol);
 154                     parentColumns [i++] = parentTable. Columns [parentCol];
 155             }
 156             // Search for the childColumns in childTable
 157             foreach (string childCol in _childColumnNames){
 158                     if (!childTable.Columns.Contains (childCol))
 159                             throw new InvalidConstraintException ("Table : " + _childTableName + "does not contain the column : " + childCol);
 160                     childColumns [j++] = childTable.Columns [childCol];
 161             }
 162             _validateColumns (parentColumns, childColumns);
 163             _parentColumns = parentColumns;
 164             _childColumns = childColumns;
 165                 }
 166
 167 #if NET_2_0
 168                 [MonoTODO]
 169                 public ForeignKeyConstraint (string constraintName, string parentTableName, string parentTableNamespace, string[] parentColumnNames, string[] childColumnNames, AcceptRejectRule acceptRejectRule, Rule deleteRule, Rule updateRule)
 170                 {
 171                         throw new NotImplementedException ();
 172                 }
 173 #endif
 174
 175                 private void _foreignKeyConstraint(string constraintName, DataColumn[] parentColumns,
 176                                 DataColumn[] childColumns)
 177                 {
 178
 179                         //Validate
 180                         _validateColumns(parentColumns, childColumns);
 181
 182                         //Set Constraint Name
 183                         base.ConstraintName = constraintName;
 184
 185                         //Keep reference to columns
 186                         _parentColumns = parentColumns;
 187                         _childColumns = childColumns;
 188                 }
 189
 190                 #endregion // Constructors
 191
 192                 #region Helpers
 193
 194                 private void _validateColumns(DataColumn[] parentColumns, DataColumn[] childColumns)
 195                 {
 196                         //not null
 197                         if (null == parentColumns || null == childColumns)
 198                                 throw new ArgumentNullException();
 199
 200                         //at least one element in each array
 201                         if (parentColumns.Length < 1 || childColumns.Length < 1)
 202                                 throw new ArgumentException("Neither ParentColumns or ChildColumns can't be" +
 203                                                 " zero length.");
 204
 205                         //same size arrays
 206                         if (parentColumns.Length != childColumns.Length)
 207                                 throw new ArgumentException("Parent columns and child columns must be the same length.");
 208
 209
 210                         DataTable ptable = parentColumns[0].Table;
 211                         DataTable ctable = childColumns[0].Table;
 212
 213                         for (int i = 0; i < parentColumns.Length; i++) {
 214                                 DataColumn pc = parentColumns[i];
 215                                 DataColumn cc = childColumns[i];
 216
 217                                 //not null check
 218                                 if (null == pc.Table)
 219                                         throw new ArgumentException("All columns must belong to a table." +
 220                                                 " ColumnName: " + pc.ColumnName + " does not belong to a table.");
 221
 222                                 //All columns must belong to the same table
 223                                 if (ptable != pc.Table)
 224                                         throw new InvalidConstraintException("Parent columns must all belong to the same table.");
 225
 226                                 //not null check
 227                                 if (null == cc.Table)
 228                                         throw new ArgumentException("All columns must belong to a table." +
 229                                                 " ColumnName: " + pc.ColumnName + " does not belong to a table.");
 230
 231                                 //All columns must belong to the same table.
 232                                 if (ctable != cc.Table)
 233                                         throw new InvalidConstraintException("Child columns must all belong to the same table.");
 234
 235                                 if (pc.CompiledExpression != null)
 236                                         throw new ArgumentException(String.Format("Cannot create a constraint based on Expression column {0}.", pc.ColumnName));
 237
 238                                 if (cc.CompiledExpression != null)
 239                                         throw new ArgumentException(String.Format("Cannot create a constraint based on Expression column {0}.", cc.ColumnName));
 240
 241                         }
 242
 243                         //Same dataset.  If both are null it's ok
 244                         if (ptable.DataSet != ctable.DataSet)
 245                         {
 246                                 //LAMESPEC: spec says InvalidConstraintExceptoin
 247                                 //      impl does InvalidOperationException
 248                                 throw new InvalidOperationException("Parent column and child column must belong to" +
 249                                                 " tables that belong to the same DataSet.");
 250
 251                         }
 252
 253
 254                         for (int i = 0; i < parentColumns.Length; i++)
 255                         {
 256                                 DataColumn pc = parentColumns[i];
 257                                 DataColumn cc = childColumns[i];
 258
 259                                 //Can't be the same column
 260                                 if (pc == cc)
 261                                         throw new InvalidOperationException("Parent and child columns can't be the same column.");
 262
 263                                 if (! pc.DataType.Equals(cc.DataType))
 264                                 {
 265                                         //LAMESPEC: spec says throw InvalidConstraintException
 266                                         //              implementation throws InvalidOperationException
 267                                         throw new InvalidConstraintException("Parent column is not type compatible with it's child"
 268                                                 + " column.");
 269                                 }
 270
 271                         }
 272
 273                 }
 274
 275
 276
 277                 private void _validateRemoveParentConstraint(ConstraintCollection sender,
 278                                 Constraint constraint, ref bool cancel, ref string failReason)
 279                 {
 280 #if !NET_1_1
 281                         //if we hold a reference to the parent then cancel it
 282                         if (constraint == _parentUniqueConstraint)
 283                         {
 284                                 cancel = true;
 285                                 failReason = "Cannot remove UniqueConstraint because the"
 286                                         + " ForeignKeyConstraint " + this.ConstraintName + " exists.";
 287                         }
 288 #endif
 289                 }
 290
 291                 //Checks to see if a related unique constraint exists
 292                 //if it doesn't then a unique constraint is created.
 293                 //if a unique constraint can't be created an exception will be thrown
 294                 private void _ensureUniqueConstraintExists(ConstraintCollection collection,
 295                                 DataColumn [] parentColumns)
 296                 {
 297                         //not null
 298                         if (null == parentColumns) throw new ArgumentNullException(
 299                                         "ParentColumns can't be null");
 300
 301                         UniqueConstraint uc = null;
 302
 303                         //see if unique constraint already exists
 304                         //if not create unique constraint
 305                         if(parentColumns[0] != null)
 306                                 uc = UniqueConstraint.GetUniqueConstraintForColumnSet(parentColumns[0].Table.Constraints, parentColumns);
 307
 308                         if (null == uc) {
 309                                 uc = new UniqueConstraint(parentColumns, false); //could throw
 310                                 parentColumns [0].Table.Constraints.Add (uc);
 311                         }
 312
 313                         //keep reference
 314                         _parentUniqueConstraint = uc;
 315                         //parentColumns [0].Table.Constraints.Add (uc);
 316                         //if this unique constraint is attempted to be removed before us
 317                         //we can fail the validation
 318                         //collection.ValidateRemoveConstraint += new DelegateValidateRemoveConstraint(
 319                         //              _validateRemoveParentConstraint);
 320                 }
 321
 322
 323                 #endregion //Helpers
 324
 325                 #region Properties
 326
 327                 [DataCategory ("Data")]
 328 #if !NET_2_0
 329                 [DataSysDescription ("For accept and reject changes, indicates what kind of cascading should take place across this relation.")]
 330 #endif
 331                 [DefaultValue (AcceptRejectRule.None)]
 332                 public virtual AcceptRejectRule AcceptRejectRule {
 333                         get { return _acceptRejectRule; }
 334                         set { _acceptRejectRule = value; }
 335                 }
 336
 337                 [DataCategory ("Data")]
 338 #if !NET_2_0
 339                 [DataSysDescription ("Indicates the child columns of this constraint.")]
 340 #endif
 341                 [ReadOnly (true)]
 342                 public virtual DataColumn[] Columns {
 343                         get { return _childColumns; }
 344                 }
 345
 346                 [DataCategory ("Data")]
 347 #if !NET_2_0
 348                 [DataSysDescription ("For deletions, indicates what kind of cascading should take place across this relation.")]
 349 #endif
 350                 [DefaultValue (Rule.Cascade)]
 351                 public virtual Rule DeleteRule {
 352                         get { return _deleteRule; }
 353                         set { _deleteRule = value; }
 354                 }
 355
 356                 [DataCategory ("Data")]
 357 #if !NET_2_0
 358                 [DataSysDescription ("For updates, indicates what kind of cascading should take place across this relation.")]
 359 #endif
 360                 [DefaultValue (Rule.Cascade)]
 361                 public virtual Rule UpdateRule {
 362                         get { return _updateRule; }
 363                         set { _updateRule = value; }
 364                 }
 365
 366                 [DataCategory ("Data")]
 367 #if !NET_2_0
 368                 [DataSysDescription ("Indicates the parent columns of this constraint.")]
 369 #endif
 370                 [ReadOnly (true)]
 371                 public virtual DataColumn[] RelatedColumns {
 372                         get { return _parentColumns; }
 373                 }
 374
 375                 [DataCategory ("Data")]
 376 #if !NET_2_0
 377                 [DataSysDescription ("Indicates the child table of this constraint.")]
 378 #endif
 379                 [ReadOnly (true)]
 380                 public virtual DataTable RelatedTable {
 381                         get {
 382                                 if (_parentColumns != null)
 383                                         if (_parentColumns.Length > 0)
 384                                                 return _parentColumns[0].Table;
 385
 386                                 throw new InvalidOperationException ("Property not accessible because 'Object reference not set to an instance of an object'");
 387                         }
 388                 }
 389
 390                 [DataCategory ("Data")]
 391 #if !NET_2_0
 392                 [DataSysDescription ("Indicates the table of this constraint.")]
 393 #endif
 394                 [ReadOnly (true)]
 395                 public override DataTable Table {
 396                         get {
 397                                 if (_childColumns != null)
 398                                         if (_childColumns.Length > 0)
 399                                                 return _childColumns[0].Table;
 400
 401                                 throw new InvalidOperationException ("Property not accessible because 'Object reference not set to an instance of an object'");
 402                         }
 403                 }
 404
 405                 internal bool DataColsNotValidated
 406                 {
 407             get {
 408                                 return (_dataColsNotValidated);
 409                         }
 410         }
 411
 412
 413                 #endregion // Properties
 414
 415                 #region Methods
 416
 417                 public override bool Equals(object key)
 418                 {
 419                         ForeignKeyConstraint fkc = key as ForeignKeyConstraint;
 420                         if (null == fkc) return false;
 421
 422                         //if the fk constrains the same columns then they are equal
 423                         if (! DataColumn.AreColumnSetsTheSame( this.RelatedColumns, fkc.RelatedColumns))
 424                                 return false;
 425                         if (! DataColumn.AreColumnSetsTheSame( this.Columns, fkc.Columns) )
 426                                 return false;
 427
 428                         return true;
 429                 }
 430
 431                 public override int GetHashCode()
 432                 {
 433                         //initialize hash1 and hash2 with default hashes
 434                         //any two DIFFERENT numbers will do here
 435                         int hash1 = 32, hash2 = 88;
 436                         int i;
 437
 438                         //derive the hash code from the columns that way
 439                         //Equals and GetHashCode return Equal objects to be the
 440                         //same
 441
 442                         //Get the first parent column hash
 443                         if (this.Columns.Length > 0)
 444                                 hash1 ^= this.Columns[0].GetHashCode();
 445
 446                         //get the rest of the parent column hashes if there any
 447                         for (i = 1; i < this.Columns.Length; i++)
 448                         {
 449                                 hash1 ^= this.Columns[1].GetHashCode();
 450
 451                         }
 452
 453                         //Get the child column hash
 454                         if (this.RelatedColumns.Length > 0)
 455                                 hash2 ^= this.Columns[0].GetHashCode();
 456
 457                         for (i = 1; i < this.RelatedColumns.Length; i++)
 458                         {
 459                                 hash2 ^= this.RelatedColumns[1].GetHashCode();
 460                         }
 461
 462                         //combine the two hashes
 463                         return hash1 ^ hash2;
 464                 }
 465
 466                 internal override void AddToConstraintCollectionSetup(
 467                                 ConstraintCollection collection)
 468                 {
 469                         if (collection.Table != Table)
 470                                 throw new InvalidConstraintException("This constraint cannot be added since ForeignKey doesn't belong to table " + RelatedTable.TableName + ".");
 471
 472                         //run Ctor rules again
 473                         _validateColumns(_parentColumns, _childColumns);
 474
 475                         //we must have a unique constraint on the parent
 476                         _ensureUniqueConstraintExists(collection, _parentColumns);
 477
 478                         //Make sure we can create this thing
 479                         //AssertConstraint();
 480                         if ( (Table.DataSet != null && Table.DataSet.EnforceConstraints)
 481                              || (Table.DataSet == null && Table.EnforceConstraints)) {
 482                                 if (IsConstraintViolated())
 483                                         throw new ArgumentException("This constraint cannot be enabled as not all values have corresponding parent values.");
 484                         }
 485                         //FIXME : if this fails and we created a unique constraint
 486                         //we should probably roll it back
 487                         // and remove index form Table
 488                 }
 489
 490                 internal override void RemoveFromConstraintCollectionCleanup(
 491                                 ConstraintCollection collection)
 492                 {
 493                         Index = null;
 494                 }
 495
 496                 internal override bool IsConstraintViolated()
 497                 {
 498                         if (Table.DataSet == null || RelatedTable.DataSet == null)
 499                                 return false;
 500
 501                         bool hasErrors = false;
 502                         foreach (DataRow row in Table.Rows) {
 503                                 // first we check if all values in _childColumns place are nulls.
 504                                 // if yes we return.
 505                                 if (row.IsNullColumns(_childColumns))
 506                                         continue;
 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                                         hasErrors = true;
 512                                         string[] values = new string[_childColumns.Length];
 513                                         for (int i = 0; i < _childColumns.Length; i++){
 514                                                 DataColumn col = _childColumns[i];
 515                                                 values[i] = row[col].ToString();
 516                                         }
 517
 518                                         row.RowError = String.Format("ForeignKeyConstraint {0} requires the child key values ({1}) to exist in the parent table.",
 519                                                 ConstraintName, String.Join(",", values));
 520                                 }
 521                         }
 522
 523                         if (hasErrors)
 524                                 //throw new ConstraintException("Failed to enable constraints. One or more rows contain values violating non-null, unique, or foreign-key constraints.");
 525                                 return true;
 526
 527                         return false;
 528                 }
 529
 530                 internal override void AssertConstraint(DataRow row)
 531                 {
 532                         // first we check if all values in _childColumns place are nulls.
 533                         // if yes we return.
 534                         if (row.IsNullColumns(_childColumns))
 535                                 return;
 536
 537                         // check whenever there is (at least one) parent row  in RelatedTable
 538                         if(!RelatedTable.RowsExist(_parentColumns,_childColumns,row)) {
 539                                 // if no parent row exists - constraint is violated
 540                                 throw new InvalidConstraintException(GetErrorMessage(row));
 541                         }
 542                 }
 543
 544                 internal override bool IsColumnContained(DataColumn column)
 545                 {
 546                         for (int i = 0; i < _parentColumns.Length; i++)
 547                                 if (column == _parentColumns[i])
 548                                         return true;
 549
 550                         for (int i = 0; i < _childColumns.Length; i++)
 551                                 if (column == _childColumns[i])
 552                                         return true;
 553
 554                         return false;
 555                 }
 556
 557                 internal override bool CanRemoveFromCollection(ConstraintCollection col, bool shouldThrow){
 558                         return true;
 559                 }
 560
 561                 private string GetErrorMessage(DataRow row)
 562                 {
 563                         System.Text.StringBuilder sb = new System.Text.StringBuilder();
 564                         for (int i = 0; i < _childColumns.Length; i++) {
 565                                 sb.Append(row[_childColumns[0]].ToString());
 566                                 if (i != _childColumns.Length - 1) {
 567                                         sb.Append(',');
 568                                 }
 569                         }
 570                         string valStr = sb.ToString();
 571                         return "ForeignKeyConstraint " + ConstraintName + " requires the child key values (" + valStr + ") to exist in the parent table.";
 572                 }
 573
 574                 #endregion // Methods
 575         }
 576
 577 }