// // System.Data.ForeignKeyConstraint.cs // // Author: // Franklin Wise // Daniel Morgan // // (C) 2002 Franklin Wise // (C) 2002 Daniel Morgan // // // Copyright (C) 2004 Novell, Inc (http://www.novell.com) // // Permission is hereby granted, free of charge, to any person obtaining // a copy of this software and associated documentation files (the // "Software"), to deal in the Software without restriction, including // without limitation the rights to use, copy, modify, merge, publish, // distribute, sublicense, and/or sell copies of the Software, and to // permit persons to whom the Software is furnished to do so, subject to // the following conditions: // // The above copyright notice and this permission notice shall be // included in all copies or substantial portions of the Software. // // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. // using System; using System.Collections; using System.ComponentModel; using System.Runtime.InteropServices; namespace System.Data { [Editor] [DefaultProperty ("ConstraintName")] [Serializable] public class ForeignKeyConstraint : Constraint { private UniqueConstraint _parentUniqueConstraint; private DataColumn [] _parentColumns; private DataColumn [] _childColumns; private DataColumn [] _childColumnsExtended; private Rule _deleteRule = Rule.Cascade; private Rule _updateRule = Rule.Cascade; private AcceptRejectRule _acceptRejectRule = AcceptRejectRule.None; private string _parentTableName; private string _childTableName; private string [] _parentColumnNames; private string [] _childColumnNames; private bool _dataColsNotValidated = false; #region Constructors public ForeignKeyConstraint(DataColumn parentColumn, DataColumn childColumn) { if (null == parentColumn || null == childColumn) { throw new NullReferenceException("Neither parentColumn or" + " childColumn can be null."); } _foreignKeyConstraint(null, new DataColumn[] {parentColumn}, new DataColumn[] {childColumn}); } public ForeignKeyConstraint(DataColumn[] parentColumns, DataColumn[] childColumns) { _foreignKeyConstraint(null, parentColumns, childColumns); } public ForeignKeyConstraint(string constraintName, DataColumn parentColumn, DataColumn childColumn) { if (null == parentColumn || null == childColumn) { throw new NullReferenceException("Neither parentColumn or" + " childColumn can be null."); } _foreignKeyConstraint(constraintName, new DataColumn[] {parentColumn}, new DataColumn[] {childColumn}); } public ForeignKeyConstraint(string constraintName, DataColumn[] parentColumns, DataColumn[] childColumns) { _foreignKeyConstraint(constraintName, parentColumns, childColumns); } //special case [Browsable (false)] public ForeignKeyConstraint(string constraintName, string parentTableName, string[] parentColumnNames, string[] childColumnNames, AcceptRejectRule acceptRejectRule, Rule deleteRule, Rule updateRule) { _dataColsNotValidated = true; base.ConstraintName = constraintName; // "parentTableName" is searched in the "DataSet" to which the "DataTable" // from which AddRange() is called // childTable is the "DataTable" which calls AddRange() // Keep reference to parentTableName to resolve later _parentTableName = parentTableName; // Keep reference to parentColumnNames to resolve later _parentColumnNames = parentColumnNames; // Keep reference to childColumnNames to resolve later _childColumnNames = childColumnNames; _acceptRejectRule = acceptRejectRule; _deleteRule = deleteRule; _updateRule = updateRule; } internal void postAddRange (DataTable childTable) { // LAMESPEC - Does not say that this is mandatory // Check whether childTable belongs to a DataSet if (childTable.DataSet == null) throw new InvalidConstraintException ("ChildTable : " + childTable.TableName + " does not belong to any DataSet"); DataSet dataSet = childTable.DataSet; _childTableName = childTable.TableName; // Search for the parentTable in the childTable's DataSet if (!dataSet.Tables.Contains (_parentTableName)) throw new InvalidConstraintException ("Table : " + _parentTableName + "does not exist in DataSet : " + dataSet); // Keep reference to parentTable DataTable parentTable = dataSet.Tables [_parentTableName]; int i = 0, j = 0; // LAMESPEC - Does not say which Exception is thrown if (_parentColumnNames.Length < 0 || _childColumnNames.Length < 0) throw new InvalidConstraintException ("Neither parent nor child columns can be zero length"); // LAMESPEC - Does not say which Exception is thrown if (_parentColumnNames.Length != _childColumnNames.Length) throw new InvalidConstraintException ("Both parent and child columns must be of same length"); DataColumn []parentColumns = new DataColumn [_parentColumnNames.Length]; DataColumn []childColumns = new DataColumn [_childColumnNames.Length]; // Search for the parentColumns in parentTable foreach (string parentCol in _parentColumnNames){ if (!parentTable.Columns.Contains (parentCol)) throw new InvalidConstraintException ("Table : " + _parentTableName + "does not contain the column :" + parentCol); parentColumns [i++] = parentTable. Columns [parentCol]; } // Search for the childColumns in childTable foreach (string childCol in _childColumnNames){ if (!childTable.Columns.Contains (childCol)) throw new InvalidConstraintException ("Table : " + _childTableName + "does not contain the column : " + childCol); childColumns [j++] = childTable.Columns [childCol]; } _validateColumns (parentColumns, childColumns); _parentColumns = parentColumns; _childColumns = childColumns; } #if NET_2_0 [MonoTODO] public ForeignKeyConstraint (string constraintName, string parentTableName, string parentTableNamespace, string[] parentColumnNames, string[] childColumnNames, AcceptRejectRule acceptRejectRule, Rule deleteRule, Rule updateRule) { throw new NotImplementedException (); } #endif private void _foreignKeyConstraint(string constraintName, DataColumn[] parentColumns, DataColumn[] childColumns) { //Validate _validateColumns(parentColumns, childColumns); //Set Constraint Name base.ConstraintName = constraintName; //Keep reference to columns _parentColumns = parentColumns; _childColumns = childColumns; } #endregion // Constructors #region Helpers private void _validateColumns(DataColumn[] parentColumns, DataColumn[] childColumns) { //not null if (null == parentColumns || null == childColumns) throw new ArgumentNullException(); //at least one element in each array if (parentColumns.Length < 1 || childColumns.Length < 1) throw new ArgumentException("Neither ParentColumns or ChildColumns can't be" + " zero length."); //same size arrays if (parentColumns.Length != childColumns.Length) throw new ArgumentException("Parent columns and child columns must be the same length."); DataTable ptable = parentColumns[0].Table; DataTable ctable = childColumns[0].Table; for (int i = 0; i < parentColumns.Length; i++) { DataColumn pc = parentColumns[i]; DataColumn cc = childColumns[i]; //not null check if (null == pc.Table) throw new ArgumentException("All columns must belong to a table." + " ColumnName: " + pc.ColumnName + " does not belong to a table."); //All columns must belong to the same table if (ptable != pc.Table) throw new InvalidConstraintException("Parent columns must all belong to the same table."); //not null check if (null == cc.Table) throw new ArgumentException("All columns must belong to a table." + " ColumnName: " + pc.ColumnName + " does not belong to a table."); //All columns must belong to the same table. if (ctable != cc.Table) throw new InvalidConstraintException("Child columns must all belong to the same table."); } //Same dataset. If both are null it's ok if (ptable.DataSet != ctable.DataSet) { //LAMESPEC: spec says InvalidConstraintExceptoin // impl does InvalidOperationException throw new InvalidOperationException("Parent column and child column must belong to" + " tables that belong to the same DataSet."); } for (int i = 0; i < parentColumns.Length; i++) { DataColumn pc = parentColumns[i]; DataColumn cc = childColumns[i]; //Can't be the same column if (pc == cc) throw new InvalidOperationException("Parent and child columns can't be the same column."); if (! pc.DataType.Equals(cc.DataType)) { //LAMESPEC: spec says throw InvalidConstraintException // implementation throws InvalidOperationException throw new InvalidConstraintException("Parent column is not type compatible with it's child" + " column."); } } } private void _validateRemoveParentConstraint(ConstraintCollection sender, Constraint constraint, ref bool cancel, ref string failReason) { #if !NET_1_1 //if we hold a reference to the parent then cancel it if (constraint == _parentUniqueConstraint) { cancel = true; failReason = "Cannot remove UniqueConstraint because the" + " ForeignKeyConstraint " + this.ConstraintName + " exists."; } #endif } //Checks to see if a related unique constraint exists //if it doesn't then a unique constraint is created. //if a unique constraint can't be created an exception will be thrown private void _ensureUniqueConstraintExists(ConstraintCollection collection, DataColumn [] parentColumns) { //not null if (null == parentColumns) throw new ArgumentNullException( "ParentColumns can't be null"); UniqueConstraint uc = null; //see if unique constraint already exists //if not create unique constraint if(parentColumns[0] != null) uc = UniqueConstraint.GetUniqueConstraintForColumnSet(parentColumns[0].Table.Constraints, parentColumns); if (null == uc) { uc = new UniqueConstraint(parentColumns, false); //could throw parentColumns [0].Table.Constraints.Add (uc); } //keep reference _parentUniqueConstraint = uc; //parentColumns [0].Table.Constraints.Add (uc); //if this unique constraint is attempted to be removed before us //we can fail the validation //collection.ValidateRemoveConstraint += new DelegateValidateRemoveConstraint( // _validateRemoveParentConstraint); parentColumns [0].Table.Constraints.ValidateRemoveConstraint += new DelegateValidateRemoveConstraint( _validateRemoveParentConstraint); } #endregion //Helpers #region Properties [DataCategory ("Data")] [DataSysDescription ("For accept and reject changes, indicates what kind of cascading should take place across this relation.")] [DefaultValue (AcceptRejectRule.None)] public virtual AcceptRejectRule AcceptRejectRule { get { return _acceptRejectRule; } set { _acceptRejectRule = value; } } [DataCategory ("Data")] [DataSysDescription ("Indicates the child columns of this constraint.")] [ReadOnly (true)] public virtual DataColumn[] Columns { get { return _childColumns; } } [DataCategory ("Data")] [DataSysDescription ("For deletions, indicates what kind of cascading should take place across this relation.")] [DefaultValue (Rule.Cascade)] public virtual Rule DeleteRule { get { return _deleteRule; } set { _deleteRule = value; } } [DataCategory ("Data")] [DataSysDescription ("For updates, indicates what kind of cascading should take place across this relation.")] [DefaultValue (Rule.Cascade)] public virtual Rule UpdateRule { get { return _updateRule; } set { _updateRule = value; } } [DataCategory ("Data")] [DataSysDescription ("Indicates the parent columns of this constraint.")] [ReadOnly (true)] public virtual DataColumn[] RelatedColumns { get { return _parentColumns; } } [DataCategory ("Data")] [DataSysDescription ("Indicates the child table of this constraint.")] [ReadOnly (true)] public virtual DataTable RelatedTable { get { if (_parentColumns != null) if (_parentColumns.Length > 0) return _parentColumns[0].Table; throw new InvalidOperationException ("Property not accessible because 'Object reference not set to an instance of an object'"); } } [DataCategory ("Data")] [DataSysDescription ("Indicates the table of this constraint.")] [ReadOnly (true)] public override DataTable Table { get { if (_childColumns != null) if (_childColumns.Length > 0) return _childColumns[0].Table; throw new InvalidOperationException ("Property not accessible because 'Object reference not set to an instance of an object'"); } } internal bool DataColsNotValidated{ get{ return (_dataColsNotValidated); } } #endregion // Properties #region Methods public override bool Equals(object key) { ForeignKeyConstraint fkc = key as ForeignKeyConstraint; if (null == fkc) return false; //if the fk constrains the same columns then they are equal if (! DataColumn.AreColumnSetsTheSame( this.RelatedColumns, fkc.RelatedColumns)) return false; if (! DataColumn.AreColumnSetsTheSame( this.Columns, fkc.Columns) ) return false; return true; } public override int GetHashCode() { //initialize hash1 and hash2 with default hashes //any two DIFFERENT numbers will do here int hash1 = 32, hash2 = 88; int i; //derive the hash code from the columns that way //Equals and GetHashCode return Equal objects to be the //same //Get the first parent column hash if (this.Columns.Length > 0) hash1 ^= this.Columns[0].GetHashCode(); //get the rest of the parent column hashes if there any for (i = 1; i < this.Columns.Length; i++) { hash1 ^= this.Columns[1].GetHashCode(); } //Get the child column hash if (this.RelatedColumns.Length > 0) hash2 ^= this.Columns[0].GetHashCode(); for (i = 1; i < this.RelatedColumns.Length; i++) { hash2 ^= this.RelatedColumns[1].GetHashCode(); } //combine the two hashes return hash1 ^ hash2; } internal override void AddToConstraintCollectionSetup( ConstraintCollection collection) { if (collection.Table != Table) throw new InvalidConstraintException("This constraint cannot be added since ForeignKey doesn't belong to table " + RelatedTable.TableName + "."); //run Ctor rules again _validateColumns(_parentColumns, _childColumns); //we must have a unique constraint on the parent _ensureUniqueConstraintExists(collection, _parentColumns); //Make sure we can create this thing AssertConstraint(); //TODO:if this fails and we created a unique constraint //we should probably roll it back // and remove index form Table } [MonoTODO] internal override void RemoveFromConstraintCollectionCleanup( ConstraintCollection collection) { // this is not referncing the index anymore Index index = this.Index; this.Index = null; // drop the extended index on child table this.Table.DropIndex(index); } [MonoTODO] internal override void AssertConstraint() { //Constraint only works if both tables are part of the same dataset //if DataSet ... if (Table == null || RelatedTable == null) return; //TODO: Do we want this if (Table.DataSet == null || RelatedTable.DataSet == null) return; // try { foreach (DataRow row in Table.Rows) { // first we check if all values in _childColumns place are nulls. // if yes we return. if (row.IsNullColumns(_childColumns)) continue; // check whenever there is (at least one) parent row in RelatedTable if(!RelatedTable.RowsExist(_parentColumns,_childColumns,row)) { // if no parent row exists - constraint is violated string values = ""; for (int i = 0; i < _childColumns.Length; i++) { values += row[_childColumns[0]].ToString(); if (i != _childColumns.Length - 1) values += ","; } throw new InvalidConstraintException("ForeignKeyConstraint " + ConstraintName + " requires the child key values (" + values + ") to exist in the parent table."); } } } catch (InvalidConstraintException){ throw new ArgumentException("This constraint cannot be enabled as not all values have corresponding parent values."); } // Create or rebuild index on Table // We create index for FK only if PK on the Table exists // and extended index is created based on appending PK columns to the // FK columns if((this.Table.PrimaryKey != null) && (this.Table.PrimaryKey.Length > 0)) { // rebuild extended columns RebuildExtendedColumns(); if(this.Index == null) { this.Index = this.Table.CreateIndex(this.ConstraintName + "_index",_childColumnsExtended,false); } if(UniqueConstraint.GetUniqueConstraintForColumnSet(this.Table.Constraints,this.Index.Columns) == null) { this.Table.InitializeIndex(this.Index); } } } [MonoTODO] internal override void AssertConstraint(DataRow row) { // first we check if all values in _childColumns place are nulls. // if yes we return. if (row.IsNullColumns(_childColumns)) return; // check whenever there is (at least one) parent row in RelatedTable if(!RelatedTable.RowsExist(_parentColumns,_childColumns,row)) { // if no parent row exists - constraint is violated string values = ""; for (int i = 0; i < _childColumns.Length; i++) { values += row[_childColumns[0]].ToString(); if (i != _childColumns.Length - 1) values += ","; } throw new InvalidConstraintException("ForeignKeyConstraint " + ConstraintName + " requires the child key values (" + values + ") to exist in the parent table."); } // if row can be inserted - add it to constraint index // if there is no UniqueConstraint on the same columns if(this.Index != null && UniqueConstraint.GetUniqueConstraintForColumnSet(this.Table.Constraints,this.Index.Columns) == null) { UpdateIndex(row); } } internal override void RollbackAssert (DataRow row) { // first we check if all values in _childColumns place are DBNull. // if yes we return. if (row.IsNullColumns(_childColumns)) return; // if there is no UniqueConstraint on the same columns // we should rollback row from index if(this.Index != null && UniqueConstraint.GetUniqueConstraintForColumnSet(this.Table.Constraints,this.Index.Columns) == null) { RollbackIndex(row); } } internal void RebuildExtendedColumns() { DataColumn[] pkColumns = this.Table.PrimaryKey; if((pkColumns != null) && (pkColumns.Length > 0)) { _childColumnsExtended = new DataColumn[_childColumns.Length + pkColumns.Length]; Array.Copy(_childColumns,0,_childColumnsExtended,0,_childColumns.Length); Array.Copy(pkColumns,0,_childColumnsExtended,_childColumns.Length,pkColumns.Length); } else { throw new InvalidOperationException("Can not extend columns for foreign key"); } } internal bool Contains (DataColumn c, bool asParent) { DataColumn [] columns = asParent? RelatedColumns : Columns; foreach (DataColumn col in columns) if (col == c) return true; return false; } #endregion // Methods } }