Expression

string System.Data.DataColumn.Expression

getset

Definition at line 586 of file DataColumn.cs.

    {
        get
        {
            if (_expression != null)
            {
                return _expression.Expression;
            }
            return "";
        }
        [RequiresUnreferencedCode("Members from types used in the expressions may be trimmed if not referenced directly.")]
        [param: AllowNull]
        set
        {
            long scopeId = DataCommonEventSource.Log.EnterScope("<ds.DataColumn.set_Expression|API> {0}, '{1}'", ObjectID, value);
            if (value == null)
            {
                value = string.Empty;
            }
            try
            {
                DataExpression dataExpression = null;
                if (value.Length > 0)
                {
                    DataExpression dataExpression2 = new DataExpression(_table, value, _dataType);
                    if (dataExpression2.HasValue)
                    {
                        dataExpression = dataExpression2;
                    }
                }
                if (_expression == null && dataExpression != null)
                {
                    if (AutoIncrement || Unique)
                    {
                        throw ExceptionBuilder.ExpressionAndUnique();
                    }
                    if (_table != null)
                    {
                        for (int i = 0; i < _table.Constraints.Count; i++)
                        {
                            if (_table.Constraints[i].ContainsColumn(this))
                            {
                                throw ExceptionBuilder.ExpressionAndConstraint(this, _table.Constraints[i]);
                            }
                        }
                    }
                    bool readOnly = ReadOnly;
                    try
                    {
                        ReadOnly = true;
                    }
                    catch (ReadOnlyException e)
                    {
                        ExceptionBuilder.TraceExceptionForCapture(e);
                        ReadOnly = readOnly;
                        throw ExceptionBuilder.ExpressionAndReadOnly();
                    }
                }
                if (_table != null)
                {
                    if (dataExpression != null && dataExpression.DependsOn(this))
                    {
                        throw ExceptionBuilder.ExpressionCircular();
                    }
                    HandleDependentColumnList(_expression, dataExpression);
                    DataExpression expression = _expression;
                    _expression = dataExpression;
                    try
                    {
                        if (dataExpression == null)
                        {
                            for (int j = 0; j < _table.RecordCapacity; j++)
                            {
                                InitializeRecord(j);
                            }
                        }
                        else
                        {
                            _table.EvaluateExpressions(this);
                        }
                        _table.ResetInternalIndexes(this);
                        _table.EvaluateDependentExpressions(this);
                        return;
                    }
                    catch (Exception e2) when (ADP.IsCatchableExceptionType(e2))
                    {
                        ExceptionBuilder.TraceExceptionForCapture(e2);
                        try
                        {
                            _expression = expression;
                            HandleDependentColumnList(dataExpression, _expression);
                            if (expression == null)
                            {
                                for (int k = 0; k < _table.RecordCapacity; k++)
                                {
                                    InitializeRecord(k);
                                }
                            }
                            else
                            {
                                _table.EvaluateExpressions(this);
                            }
                            _table.ResetInternalIndexes(this);
                            _table.EvaluateDependentExpressions(this);
                        }
                        catch (Exception e3) when (ADP.IsCatchableExceptionType(e3))
                        {
                            ExceptionBuilder.TraceExceptionWithoutRethrow(e3);
                        }
                        throw;
                    }
                }
                _expression = dataExpression;
            }
            finally
            {
                DataCommonEventSource.Log.ExitScope(scopeId);
            }
        }
    }

Referenced by System.Data.DataColumn.DataColumn(), System.Data.DataColumn.CopyExpressionFrom(), System.Data.Common.DataColumnMapping.GetDataColumnBySchemaAction(), System.Data.DataTableReader.GetSchemaTableFromDataTable(), and System.Data.DataColumn.ToString().