mcs/class/System.Data/System.Data/Constraint.cs

   1 //
   2 // System.Data.Constraint.cs
   3 //
   4 // Author:
   5 //      Franklin Wise <gracenote@earthlink.net>
   6 //      Daniel Morgan
   7 //      Tim Coleman (tim@timcoleman.com)
   8 //
   9 //
  10 // (C) Ximian, Inc. 2002
  11 // Copyright (C) Tim Coleman, 2002
  12 //
  13
  14 //
  15 // Copyright (C) 2004 Novell, Inc (http://www.novell.com)
  16 //
  17 // Permission is hereby granted, free of charge, to any person obtaining
  18 // a copy of this software and associated documentation files (the
  19 // "Software"), to deal in the Software without restriction, including
  20 // without limitation the rights to use, copy, modify, merge, publish,
  21 // distribute, sublicense, and/or sell copies of the Software, and to
  22 // permit persons to whom the Software is furnished to do so, subject to
  23 // the following conditions:
  24 //
  25 // The above copyright notice and this permission notice shall be
  26 // included in all copies or substantial portions of the Software.
  27 //
  28 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  29 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  30 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  31 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  32 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  33 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  34 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  35 //
  36
  37 using System;
  38 using System.Collections;
  39 using System.ComponentModel;
  40 using System.Runtime.InteropServices;
  41 using System.Runtime.Serialization;
  42
  43 namespace System.Data {
  44         [Serializable]
  45         internal delegate void DelegateConstraintNameChange (object sender, string newName);
  46
  47         [DefaultProperty ("ConstraintName")]
  48         [Serializable]
  49         [TypeConverterAttribute (typeof (ConstraintConverter))]
  50         public abstract class Constraint
  51         {
  52                 internal event DelegateConstraintNameChange BeforeConstraintNameChange;
  53
  54                 //if constraintName is not set then a name is
  55                 //created when it is added to
  56                 //the ConstraintCollection
  57                 //it can not be set to null, empty or duplicate
  58                 //once it has been added to the collection
  59                 private string _constraintName;
  60                 private PropertyCollection _properties;
  61
  62                 private Index _index;
  63
  64                 //Used for membership checking
  65                 private ConstraintCollection _constraintCollection;
  66
  67                 DataSet dataSet;
  68
  69                 protected Constraint ()
  70                 {
  71                         dataSet = null;
  72                         _properties = new PropertyCollection();
  73                 }
  74
  75                 [CLSCompliant (false)]
  76                 protected internal virtual DataSet _DataSet {
  77                         get { return dataSet; }
  78                 }
  79
  80                 [DataCategory ("Data")]
  81                 [DataSysDescription ("Indicates the name of this constraint.")]
  82                 [DefaultValue ("")]
  83                 public virtual string ConstraintName {
  84                         get{ return _constraintName == null ? "" : _constraintName; }
  85                         set{
  86                                 //This should only throw an exception when it
  87                                 //is a member of a ConstraintCollection which
  88                                 //means we should let the ConstraintCollection
  89                                 //handle exceptions when this value changes
  90                                 _onConstraintNameChange(value);
  91                                 _constraintName = value;
  92                         }
  93                 }
  94
  95                 [Browsable (false)]
  96                 [DataCategory ("Data")]
  97                 [DataSysDescription ("The collection that holds custom user information.")]
  98                 public PropertyCollection ExtendedProperties {
  99                         get { return _properties; }
 100                 }
 101
 102                 [DataSysDescription ("Indicates the table of this constraint.")]
 103                 public abstract DataTable Table {
 104                         get;
 105                 }
 106
 107                 internal ConstraintCollection ConstraintCollection {
 108                         get{ return _constraintCollection; }
 109                         set{ _constraintCollection = value; }
 110                 }
 111
 112                 private void _onConstraintNameChange (string newName)
 113                 {
 114                         if (null != BeforeConstraintNameChange)
 115                         {
 116                                 BeforeConstraintNameChange (this, newName);
 117                         }
 118                 }
 119
 120                 //call once before adding a constraint to a collection
 121                 //will throw an exception to prevent the add if a rule is broken
 122                 internal virtual void AddToConstraintCollectionSetup (ConstraintCollection collection)
 123                 {
 124                 }
 125
 126                 internal virtual void AssertConstraint ()
 127                 {
 128                 }
 129
 130                 internal virtual void AssertConstraint (DataRow row)
 131                 {
 132                 }
 133
 134                 internal virtual void RollbackAssert (DataRow row)
 135                 {
 136                 }
 137
 138                 //call once before removing a constraint to a collection
 139                 //can throw an exception to prevent the removal
 140                 internal virtual void RemoveFromConstraintCollectionCleanup (ConstraintCollection collection)
 141                 {
 142                 }
 143
 144                 [MonoTODO]
 145                 protected void CheckStateForProperty ()
 146                 {
 147                         throw new NotImplementedException ();
 148                 }
 149
 150                 protected internal void SetDataSet (DataSet dataSet)
 151                 {
 152                         this.dataSet = dataSet;
 153                 }
 154
 155                 internal Index Index
 156                 {
 157                         get {
 158                                 return _index;
 159                         }
 160                         set {
 161                                 _index = value;
 162                         }
 163                 }
 164
 165                 internal void UpdateIndex (DataRow row)
 166                 {
 167                         if (row.RowState == DataRowState.Detached || row.RowState == DataRowState.Unchanged)
 168                                 Index.Insert (new Node (row), DataRowVersion.Default);
 169                         else if ((row.RowState == DataRowState.Modified) || (row.RowState == DataRowState.Added)) {
 170                                 // first we check if the values of the key changed.
 171                                 bool keyChanged = false;
 172                                 for (int i = 0; i < Index.Columns.Length; i++) {
 173                                         if (row[Index.Columns[i], DataRowVersion.Default] != row[Index.Columns[i], DataRowVersion.Current]) {
 174                                                 keyChanged = true;
 175                                         }
 176                                 }
 177                                 // if key changed we first try to insert a new node
 178                                 // and,if succeded, we delete the row's old node.
 179                                 if (keyChanged)
 180                                 {
 181                                         // insert new node for the row
 182                                         // note : may throw if not succeded
 183                                         Index.Insert (new Node (row), DataRowVersion.Default);
 184
 185                                         // delete the row's node
 186                                         Index.Delete(row);
 187                                 }
 188                         }
 189                 }
 190
 191                 internal void RollbackIndex (DataRow row)
 192                 {
 193                         Node n = Index.Find(row, DataRowVersion.Default);
 194                         if ( n == null)
 195                                 throw new ConstraintException("Row was not found in constraint index");
 196
 197                         // first remove the node inserted as a result of last AssertConstraint on the row
 198                         Index.Delete(n);
 199
 200                         // if the row is not detached we should add back to the index
 201                         // node corresponding to row value before AssertConstraint was called
 202                         if(row.RowState != DataRowState.Detached){
 203                                 // since index before we updated index was ok, insert should always suceed
 204                                 // maybe we still need to try/catch here
 205                                 Index.Insert(new Node(row), DataRowVersion.Current);
 206                         }
 207                 }
 208
 209
 210                 /// <summary>
 211                 /// Gets the ConstraintName, if there is one, as a string.
 212                 /// </summary>
 213                 public override string ToString ()
 214                 {
 215                         return _constraintName == null ? "" : _constraintName;
 216                 }
 217
 218         }
 219 }