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 using System;
  15 using System.Collections;
  16 using System.ComponentModel;
  17 using System.Runtime.InteropServices;
  18 using System.Runtime.Serialization;
  19
  20 namespace System.Data {
  21         [Serializable]
  22         internal delegate void DelegateConstraintNameChange (object sender, string newName);
  23
  24         [DefaultProperty ("ConstraintName")]
  25         [Serializable]
  26         [TypeConverterAttribute (typeof (ConstraintConverter))]
  27         public abstract class Constraint
  28         {
  29                 internal event DelegateConstraintNameChange BeforeConstraintNameChange;
  30
  31                 //if constraintName is not set then a name is
  32                 //created when it is added to
  33                 //the ConstraintCollection
  34                 //it can not be set to null, empty or duplicate
  35                 //once it has been added to the collection
  36                 private string _constraintName;
  37                 private PropertyCollection _properties;
  38
  39                 private Index _index;
  40
  41                 //Used for membership checking
  42                 private ConstraintCollection _constraintCollection;
  43
  44                 DataSet dataSet;
  45
  46                 protected Constraint ()
  47                 {
  48                         dataSet = null;
  49                         _properties = new PropertyCollection();
  50                 }
  51
  52                 protected internal virtual DataSet _DataSet {
  53                         get { return dataSet; }
  54                 }
  55
  56                 [DataCategory ("Data")]
  57                 [DataSysDescription ("Indicates the name of this constraint.")]
  58                 [DefaultValue ("")]
  59                 public virtual string ConstraintName {
  60                         get{ return "" + _constraintName; }
  61                         set{
  62                                 //This should only throw an exception when it
  63                                 //is a member of a ConstraintCollection which
  64                                 //means we should let the ConstraintCollection
  65                                 //handle exceptions when this value changes
  66                                 _onConstraintNameChange(value);
  67                                 _constraintName = value;
  68                         }
  69                 }
  70
  71                 [Browsable (false)]
  72                 [DataCategory ("Data")]
  73                 [DataSysDescription ("The collection that holds custom user information.")]
  74                 public PropertyCollection ExtendedProperties {
  75                         get { return _properties; }
  76                 }
  77
  78                 [DataSysDescription ("Indicates the table of this constraint.")]
  79                 public abstract DataTable Table {
  80                         get;
  81                 }
  82
  83                 internal ConstraintCollection ConstraintCollection {
  84                         get{ return _constraintCollection; }
  85                         set{ _constraintCollection = value; }
  86                 }
  87
  88                 private void _onConstraintNameChange (string newName)
  89                 {
  90                         if (null != BeforeConstraintNameChange)
  91                         {
  92                                 BeforeConstraintNameChange (this, newName);
  93                         }
  94                 }
  95
  96                 //call once before adding a constraint to a collection
  97                 //will throw an exception to prevent the add if a rule is broken
  98                 internal virtual void AddToConstraintCollectionSetup (ConstraintCollection collection)
  99                 {
 100                 }
 101
 102                 internal virtual void AssertConstraint ()
 103                 {
 104                 }
 105
 106                 internal virtual void AssertConstraint (DataRow row)
 107                 {
 108                 }
 109
 110                 internal virtual void RollbackAssert (DataRow row)
 111                 {
 112                 }
 113
 114                 //call once before removing a constraint to a collection
 115                 //can throw an exception to prevent the removal
 116                 internal virtual void RemoveFromConstraintCollectionCleanup (ConstraintCollection collection)
 117                 {
 118                 }
 119
 120                 [MonoTODO]
 121                 protected void CheckStateForProperty ()
 122                 {
 123                         throw new NotImplementedException ();
 124                 }
 125
 126                 protected internal void SetDataSet (DataSet dataSet)
 127                 {
 128                         this.dataSet = dataSet;
 129                 }
 130
 131                 internal Index Index
 132                 {
 133                         get {
 134                                 return _index;
 135                         }
 136                         set {
 137                                 _index = value;
 138                         }
 139                 }
 140
 141                 protected internal void UpdateIndex (DataRow row)
 142                 {
 143                         if (row.RowState == DataRowState.Detached || row.RowState == DataRowState.Unchanged)
 144                                 Index.Insert (new Node (row), DataRowVersion.Default);
 145                         else if ((row.RowState == DataRowState.Modified) || (row.RowState == DataRowState.Added)) {
 146                                 // first we check if the values of the key changed.
 147                                 bool keyChanged = false;
 148                                 for (int i = 0; i < Index.Columns.Length; i++) {
 149                                         if (row[Index.Columns[i], DataRowVersion.Default] != row[Index.Columns[i], DataRowVersion.Current]) {
 150                                                 keyChanged = true;
 151                                         }
 152                                 }
 153                                 // if key changed we first try to insert a new node
 154                                 // and,if succeded, we delete the row's old node.
 155                                 if (keyChanged)
 156                                 {
 157                                         // insert new node for the row
 158                                         // note : may throw if not succeded
 159                                         Index.Insert (new Node (row), DataRowVersion.Default);
 160
 161                                         // delete the row's node
 162                                         Index.Delete(row);
 163                                 }
 164                         }
 165                 }
 166
 167                 protected internal void RollbackIndex (DataRow row)
 168                 {
 169                         Node n = Index.Find(row, DataRowVersion.Default);
 170                         if ( n == null)
 171                                 throw new ConstraintException("Row was not found in constraint index");
 172
 173                         // first remove the node inserted as a result of last AssertConstraint on the row
 174                         Index.Delete(n);
 175
 176                         // if the row is not detached we should add back to the index
 177                         // node corresponding to row value before AssertConstraint was called
 178                         if(row.RowState != DataRowState.Detached){
 179                                 // since index before we updated index was ok, insert should always suceed
 180                                 // maybe we still need to try/catch here
 181                                 Index.Insert(new Node(row), DataRowVersion.Current);
 182                         }
 183                 }
 184
 185
 186                 /// <summary>
 187                 /// Gets the ConstraintName, if there is one, as a string.
 188                 /// </summary>
 189                 public override string ToString ()
 190                 {
 191                         return "" + _constraintName;
 192                 }
 193
 194         }
 195 }