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         [Serializable]
  46         public class ForeignKeyConstraint : Constraint
  47         {
  48                 private UniqueConstraint _parentUniqueConstraint;
  49                 //FIXME: create a class which will wrap this collection
  50                 private DataColumn [] _parentColumns;
  51                 //FIXME: create a class which will wrap this collection
  52                 private DataColumn [] _childColumns;
  53                 private Rule _deleteRule = Rule.Cascade;
  54                 private Rule _updateRule = Rule.Cascade;
  55                 private AcceptRejectRule _acceptRejectRule = AcceptRejectRule.None;
  56             private string _parentTableName;
  57         private string _childTableName;
  58                 //FIXME: remove those; and use only DataColumns[]
  59         private string [] _parentColumnNames;
  60         private string [] _childColumnNames;
  61         private bool _dataColsNotValidated = false;
  62
  63                 #region Constructors
  64
  65                 public ForeignKeyConstraint(DataColumn parentColumn, DataColumn childColumn)
  66                 {
  67                         if (null == parentColumn || null == childColumn) {
  68                                 throw new NullReferenceException("Neither parentColumn or" +
  69                                         " childColumn can be null.");
  70                         }
  71                         _foreignKeyConstraint(null, new DataColumn[] {parentColumn},
  72                                         new DataColumn[] {childColumn});
  73                 }
  74
  75                 public ForeignKeyConstraint(DataColumn[] parentColumns, DataColumn[] childColumns)
  76                 {
  77                         _foreignKeyConstraint(null, parentColumns, childColumns);
  78                 }
  79
  80                 public ForeignKeyConstraint(string constraintName, DataColumn parentColumn, DataColumn childColumn)
  81                 {
  82                         if (null == parentColumn || null == childColumn) {
  83                                 throw new NullReferenceException("Neither parentColumn or" +
  84                                         " childColumn can be null.");
  85                         }
  86
  87                         _foreignKeyConstraint(constraintName, new DataColumn[] {parentColumn},
  88                                         new DataColumn[] {childColumn});
  89                 }
  90
  91                 public ForeignKeyConstraint(string constraintName, DataColumn[] parentColumns, DataColumn[] childColumns)
  92                 {
  93                         _foreignKeyConstraint(constraintName, parentColumns, childColumns);
  94                 }
  95
  96                 //special case
  97                 [Browsable (false)]
  98                 public ForeignKeyConstraint(string constraintName, string parentTableName, string[] parentColumnNames, string[] childColumnNames, AcceptRejectRule acceptRejectRule, Rule deleteRule, Rule updateRule)
  99                 {
 100                         _dataColsNotValidated = true;
 101             base.ConstraintName = constraintName;
 102
 103             // "parentTableName" is searched in the "DataSet" to which the "DataTable"
 104             // from which AddRange() is called
 105             // childTable is the "DataTable" which calls AddRange()
 106
 107             // Keep reference to parentTableName to resolve later
 108             _parentTableName = parentTableName;
 109
 110             // Keep reference to parentColumnNames to resolve later
 111             _parentColumnNames = parentColumnNames;
 112
 113             // Keep reference to childColumnNames to resolve later
 114             _childColumnNames = childColumnNames;
 115
 116             _acceptRejectRule = acceptRejectRule;
 117             _deleteRule = deleteRule;
 118             _updateRule = updateRule;
 119
 120                 }
 121
 122                 internal void postAddRange (DataTable childTable)
 123         {
 124             // LAMESPEC - Does not say that this is mandatory
 125             // Check whether childTable belongs to a DataSet
 126             if (childTable.DataSet == null)
 127                     throw new InvalidConstraintException ("ChildTable : " + childTable.TableName + " does not belong to any DataSet");
 128             DataSet dataSet = childTable.DataSet;
 129             _childTableName = childTable.TableName;
 130             // Search for the parentTable in the childTable's DataSet
 131             if (!dataSet.Tables.Contains (_parentTableName))
 132                     throw new InvalidConstraintException ("Table : " + _parentTableName + "does not exist in DataSet : " + dataSet);
 133
 134             // Keep reference to parentTable
 135             DataTable parentTable = dataSet.Tables [_parentTableName];
 136
 137             int i = 0, j = 0;
 138
 139             // LAMESPEC - Does not say which Exception is thrown
 140             if (_parentColumnNames.Length < 0 || _childColumnNames.Length < 0)
 141                     throw new InvalidConstraintException ("Neither parent nor child columns can be zero length");
 142             // LAMESPEC - Does not say which Exception is thrown
 143             if (_parentColumnNames.Length != _childColumnNames.Length)
 144                                 throw new InvalidConstraintException ("Both parent and child columns must be of same length");
 145             DataColumn []parentColumns = new DataColumn [_parentColumnNames.Length];
 146             DataColumn []childColumns = new DataColumn [_childColumnNames.Length];
 147
 148             // Search for the parentColumns in parentTable
 149             foreach (string parentCol in _parentColumnNames){
 150                     if (!parentTable.Columns.Contains (parentCol))
 151                             throw new InvalidConstraintException ("Table : " + _parentTableName + "does not contain the column :" + parentCol);
 152                     parentColumns [i++] = parentTable. Columns [parentCol];
 153             }
 154             // Search for the childColumns in childTable
 155             foreach (string childCol in _childColumnNames){
 156                     if (!childTable.Columns.Contains (childCol))
 157                             throw new InvalidConstraintException ("Table : " + _childTableName + "does not contain the column : " + childCol);
 158                     childColumns [j++] = childTable.Columns [childCol];
 159             }
 160             _validateColumns (parentColumns, childColumns);
 161             _parentColumns = parentColumns;
 162             _childColumns = childColumns;
 163                 }
 164
 165 #if NET_2_0
 166                 [MonoTODO]
 167                 public ForeignKeyConstraint (string constraintName, string parentTableName, string parentTableNamespace, string[] parentColumnNames, string[] childColumnNames, AcceptRejectRule acceptRejectRule, Rule deleteRule, Rule updateRule)
 168                 {
 169                         throw new NotImplementedException ();
 170                 }
 171 #endif
 172
 173                 private void _foreignKeyConstraint(string constraintName, DataColumn[] parentColumns,
 174                                 DataColumn[] childColumns)
 175                 {
 176
 177                         //Validate
 178                         _validateColumns(parentColumns, childColumns);
 179
 180                         //Set Constraint Name
 181                         base.ConstraintName = constraintName;
 182
 183                         //Keep reference to columns
 184                         _parentColumns = parentColumns;
 185                         _childColumns = childColumns;
 186                 }
 187
 188                 #endregion // Constructors
 189
 190                 #region Helpers
 191
 192                 private void _validateColumns(DataColumn[] parentColumns, DataColumn[] childColumns)
 193                 {
 194                         //not null
 195                         if (null == parentColumns || null == childColumns)
 196                                 throw new ArgumentNullException();
 197
 198                         //at least one element in each array
 199                         if (parentColumns.Length < 1 || childColumns.Length < 1)
 200                                 throw new ArgumentException("Neither ParentColumns or ChildColumns can't be" +
 201                                                 " zero length.");
 202
 203                         //same size arrays
 204                         if (parentColumns.Length != childColumns.Length)
 205                                 throw new ArgumentException("Parent columns and child columns must be the same length.");
 206
 207
 208                         DataTable ptable = parentColumns[0].Table;
 209                         DataTable ctable = childColumns[0].Table;
 210
 211                         for (int i = 0; i < parentColumns.Length; i++) {
 212                                 DataColumn pc = parentColumns[i];
 213                                 DataColumn cc = childColumns[i];
 214
 215                                 //not null check
 216                                 if (null == pc.Table)
 217                                         throw new ArgumentException("All columns must belong to a table." +
 218                                                 " ColumnName: " + pc.ColumnName + " does not belong to a table.");
 219
 220                                 //All columns must belong to the same table
 221                                 if (ptable != pc.Table)
 222                                         throw new InvalidConstraintException("Parent columns must all belong to the same table.");
 223
 224                                 //not null check
 225                                 if (null == cc.Table)
 226                                         throw new ArgumentException("All columns must belong to a table." +
 227                                                 " ColumnName: " + pc.ColumnName + " does not belong to a table.");
 228
 229                                 //All columns must belong to the same table.
 230                                 if (ctable != cc.Table)
 231                                         throw new InvalidConstraintException("Child columns must all belong to the same table.");
 232
 233                                 if (pc.CompiledExpression != null)
 234                                         throw new ArgumentException(String.Format("Cannot create a constraint based on Expression column {0}.", pc.ColumnName));
 235
 236                                 if (cc.CompiledExpression != null)
 237                                         throw new ArgumentException(String.Format("Cannot create a constraint based on Expression column {0}.", cc.ColumnName));
 238
 239                         }
 240
 241                         //Same dataset.  If both are null it's ok
 242                         if (ptable.DataSet != ctable.DataSet)
 243                         {
 244                                 //LAMESPEC: spec says InvalidConstraintExceptoin
 245                                 //      impl does InvalidOperationException
 246                                 throw new InvalidOperationException("Parent column and child column must belong to" +
 247                                                 " tables that belong to the same DataSet.");
 248
 249                         }
 250
 251
 252                         for (int i = 0; i < parentColumns.Length; i++)
 253                         {
 254                                 DataColumn pc = parentColumns[i];
 255                                 DataColumn cc = childColumns[i];
 256
 257                                 //Can't be the same column
 258                                 if (pc == cc)
 259                                         throw new InvalidOperationException("Parent and child columns can't be the same column.");
 260
 261                                 if (! pc.DataType.Equals(cc.DataType))
 262                                 {
 263                                         //LAMESPEC: spec says throw InvalidConstraintException
 264                                         //              implementation throws InvalidOperationException
 265                                         throw new InvalidConstraintException("Parent column is not type compatible with it's child"
 266                                                 + " column.");
 267                                 }
 268
 269                         }
 270
 271                 }
 272
 273
 274
 275                 private void _validateRemoveParentConstraint(ConstraintCollection sender,
 276                                 Constraint constraint, ref bool cancel, ref string failReason)
 277                 {
 278 #if !NET_1_1
 279                         //if we hold a reference to the parent then cancel it
 280                         if (constraint == _parentUniqueConstraint)
 281                         {
 282                                 cancel = true;
 283                                 failReason = "Cannot remove UniqueConstraint because the"
 284                                         + " ForeignKeyConstraint " + this.ConstraintName + " exists.";
 285                         }
 286 #endif
 287                 }
 288
 289                 //Checks to see if a related unique constraint exists
 290                 //if it doesn't then a unique constraint is created.
 291                 //if a unique constraint can't be created an exception will be thrown
 292                 private void _ensureUniqueConstraintExists(ConstraintCollection collection,
 293                                 DataColumn [] parentColumns)
 294                 {
 295                         //not null
 296                         if (null == parentColumns) throw new ArgumentNullException(
 297                                         "ParentColumns can't be null");
 298
 299                         UniqueConstraint uc = null;
 300
 301                         //see if unique constraint already exists
 302                         //if not create unique constraint
 303                         if(parentColumns[0] != null)
 304                                 uc = UniqueConstraint.GetUniqueConstraintForColumnSet(parentColumns[0].Table.Constraints, parentColumns);
 305
 306                         if (null == uc) {
 307                                 uc = new UniqueConstraint(parentColumns, false); //could throw
 308                                 parentColumns [0].Table.Constraints.Add (uc);
 309                         }
 310
 311                         //keep reference
 312                         _parentUniqueConstraint = uc;
 313                         //parentColumns [0].Table.Constraints.Add (uc);
 314                         //if this unique constraint is attempted to be removed before us
 315                         //we can fail the validation
 316                         //collection.ValidateRemoveConstraint += new DelegateValidateRemoveConstraint(
 317                         //              _validateRemoveParentConstraint);
 318                 }
 319
 320
 321                 #endregion //Helpers
 322
 323                 #region Properties
 324
 325                 [DataCategory ("Data")]
 326                 [DataSysDescription ("For accept and reject changes, indicates what kind of cascading should take place across this relation.")]
 327                 [DefaultValue (AcceptRejectRule.None)]
 328                 public virtual AcceptRejectRule AcceptRejectRule {
 329                         get { return _acceptRejectRule; }
 330                         set { _acceptRejectRule = value; }
 331                 }
 332
 333                 [DataCategory ("Data")]
 334                 [DataSysDescription ("Indicates the child columns of this constraint.")]
 335                 [ReadOnly (true)]
 336                 public virtual DataColumn[] Columns {
 337                         get { return _childColumns; }
 338                 }
 339
 340                 [DataCategory ("Data")]
 341                 [DataSysDescription ("For deletions, indicates what kind of cascading should take place across this relation.")]
 342                 [DefaultValue (Rule.Cascade)]
 343                 public virtual Rule DeleteRule {
 344                         get { return _deleteRule; }
 345                         set { _deleteRule = value; }
 346                 }
 347
 348                 [DataCategory ("Data")]
 349                 [DataSysDescription ("For updates, indicates what kind of cascading should take place across this relation.")]
 350                 [DefaultValue (Rule.Cascade)]
 351                 public virtual Rule UpdateRule {
 352                         get { return _updateRule; }
 353                         set { _updateRule = value; }
 354                 }
 355
 356                 [DataCategory ("Data")]
 357                 [DataSysDescription ("Indicates the parent columns of this constraint.")]
 358                 [ReadOnly (true)]
 359                 public virtual DataColumn[] RelatedColumns {
 360                         get { return _parentColumns; }
 361                 }
 362
 363                 [DataCategory ("Data")]
 364                 [DataSysDescription ("Indicates the child table of this constraint.")]
 365                 [ReadOnly (true)]
 366                 public virtual DataTable RelatedTable {
 367                         get {
 368                                 if (_parentColumns != null)
 369                                         if (_parentColumns.Length > 0)
 370                                                 return _parentColumns[0].Table;
 371
 372                                 throw new InvalidOperationException ("Property not accessible because 'Object reference not set to an instance of an object'");
 373                         }
 374                 }
 375
 376                 [DataCategory ("Data")]
 377                 [DataSysDescription ("Indicates the table of this constraint.")]
 378                 [ReadOnly (true)]
 379                 public override DataTable Table {
 380                         get {
 381                                 if (_childColumns != null)
 382                                         if (_childColumns.Length > 0)
 383                                                 return _childColumns[0].Table;
 384
 385                                 throw new InvalidOperationException ("Property not accessible because 'Object reference not set to an instance of an object'");
 386                         }
 387                 }
 388
 389                 internal bool DataColsNotValidated
 390                 {
 391             get {
 392                                 return (_dataColsNotValidated);
 393                         }
 394         }
 395
 396
 397                 #endregion // Properties
 398
 399                 #region Methods
 400
 401                 public override bool Equals(object key)
 402                 {
 403                         ForeignKeyConstraint fkc = key as ForeignKeyConstraint;
 404                         if (null == fkc) return false;
 405
 406                         //if the fk constrains the same columns then they are equal
 407                         if (! DataColumn.AreColumnSetsTheSame( this.RelatedColumns, fkc.RelatedColumns))
 408                                 return false;
 409                         if (! DataColumn.AreColumnSetsTheSame( this.Columns, fkc.Columns) )
 410                                 return false;
 411
 412                         return true;
 413                 }
 414
 415                 public override int GetHashCode()
 416                 {
 417                         //initialize hash1 and hash2 with default hashes
 418                         //any two DIFFERENT numbers will do here
 419                         int hash1 = 32, hash2 = 88;
 420                         int i;
 421
 422                         //derive the hash code from the columns that way
 423                         //Equals and GetHashCode return Equal objects to be the
 424                         //same
 425
 426                         //Get the first parent column hash
 427                         if (this.Columns.Length > 0)
 428                                 hash1 ^= this.Columns[0].GetHashCode();
 429
 430                         //get the rest of the parent column hashes if there any
 431                         for (i = 1; i < this.Columns.Length; i++)
 432                         {
 433                                 hash1 ^= this.Columns[1].GetHashCode();
 434
 435                         }
 436
 437                         //Get the child column hash
 438                         if (this.RelatedColumns.Length > 0)
 439                                 hash2 ^= this.Columns[0].GetHashCode();
 440
 441                         for (i = 1; i < this.RelatedColumns.Length; i++)
 442                         {
 443                                 hash2 ^= this.RelatedColumns[1].GetHashCode();
 444                         }
 445
 446                         //combine the two hashes
 447                         return hash1 ^ hash2;
 448                 }
 449
 450                 internal override void AddToConstraintCollectionSetup(
 451                                 ConstraintCollection collection)
 452                 {
 453                         if (collection.Table != Table)
 454                                 throw new InvalidConstraintException("This constraint cannot be added since ForeignKey doesn't belong to table " + RelatedTable.TableName + ".");
 455
 456                         //run Ctor rules again
 457                         _validateColumns(_parentColumns, _childColumns);
 458
 459                         //we must have a unique constraint on the parent
 460                         _ensureUniqueConstraintExists(collection, _parentColumns);
 461
 462                         //Make sure we can create this thing
 463                         //AssertConstraint();
 464                         if ( (Table.DataSet != null && Table.DataSet.EnforceConstraints)
 465                              || (Table.DataSet == null && Table.EnforceConstraints)) {
 466                                 if (IsConstraintViolated())
 467                                         throw new ArgumentException("This constraint cannot be enabled as not all values have corresponding parent values.");
 468                         }
 469                         //FIXME : if this fails and we created a unique constraint
 470                         //we should probably roll it back
 471                         // and remove index form Table
 472                 }
 473
 474                 internal override void RemoveFromConstraintCollectionCleanup(
 475                                 ConstraintCollection collection)
 476                 {
 477                         Index = null;
 478                 }
 479
 480                 internal override bool IsConstraintViolated()
 481                 {
 482                         if (Table.DataSet == null || RelatedTable.DataSet == null)
 483                                 return false;
 484
 485                         bool hasErrors = false;
 486                         foreach (DataRow row in Table.Rows) {
 487                                 // first we check if all values in _childColumns place are nulls.
 488                                 // if yes we return.
 489                                 if (row.IsNullColumns(_childColumns))
 490                                         continue;
 491
 492                                 // check whenever there is (at least one) parent row  in RelatedTable
 493                                 if(!RelatedTable.RowsExist(_parentColumns,_childColumns,row)) {
 494                                         // if no parent row exists - constraint is violated
 495                                         hasErrors = true;
 496                                         string[] values = new string[_childColumns.Length];
 497                                         for (int i = 0; i < _childColumns.Length; i++){
 498                                                 DataColumn col = _childColumns[i];
 499                                                 values[i] = row[col].ToString();
 500                                         }
 501
 502                                         row.RowError = String.Format("ForeignKeyConstraint {0} requires the child key values ({1}) to exist in the parent table.",
 503                                                 ConstraintName, String.Join(",", values));
 504                                 }
 505                         }
 506
 507                         if (hasErrors)
 508                                 //throw new ConstraintException("Failed to enable constraints. One or more rows contain values violating non-null, unique, or foreign-key constraints.");
 509                                 return true;
 510
 511                         return false;
 512                 }
 513
 514                 internal override void AssertConstraint(DataRow row)
 515                 {
 516                         // first we check if all values in _childColumns place are nulls.
 517                         // if yes we return.
 518                         if (row.IsNullColumns(_childColumns))
 519                                 return;
 520
 521                         // check whenever there is (at least one) parent row  in RelatedTable
 522                         if(!RelatedTable.RowsExist(_parentColumns,_childColumns,row)) {
 523                                 // if no parent row exists - constraint is violated
 524                                 throw new InvalidConstraintException(GetErrorMessage(row));
 525                         }
 526                 }
 527
 528                 internal override bool IsColumnContained(DataColumn column)
 529                 {
 530                         for (int i = 0; i < _parentColumns.Length; i++)
 531                                 if (column == _parentColumns[i])
 532                                         return true;
 533
 534                         for (int i = 0; i < _childColumns.Length; i++)
 535                                 if (column == _childColumns[i])
 536                                         return true;
 537
 538                         return false;
 539                 }
 540
 541                 internal override bool CanRemoveFromCollection(ConstraintCollection col, bool shouldThrow){
 542                         return true;
 543                 }
 544
 545                 private string GetErrorMessage(DataRow row)
 546                 {
 547                         System.Text.StringBuilder sb = new System.Text.StringBuilder();
 548                         for (int i = 0; i < _childColumns.Length; i++) {
 549                                 sb.Append(row[_childColumns[0]].ToString());
 550                                 if (i != _childColumns.Length - 1) {
 551                                         sb.Append(',');
 552                                 }
 553                         }
 554                         string valStr = sb.ToString();
 555                         return "ForeignKeyConstraint " + ConstraintName + " requires the child key values (" + valStr + ") to exist in the parent table.";
 556                 }
 557
 558                 #endregion // Methods
 559         }
 560
 561 }