Opc.Ua.FilterOperand.Validate C# (CSharp) Method

        public virtual ServiceResult Validate(FilterContext context, int index)
        {
            return ServiceResult.Create(StatusCodes.BadEventFilterInvalid, "A sub-class of FilterOperand must be specified.");
        }

        /// <summary>
        /// Validates the content filter element.
        /// </summary>
        /// <param name="context">The context.</param>
        /// <param name="index">The index.</param>
        /// <returns>The results of the validation.</returns>
        public virtual ContentFilter.ElementResult Validate(FilterContext context, int index)
        {
            ContentFilter.ElementResult result = new ContentFilter.ElementResult(null);

            // check the number of operands.
            int operandCount = -1;

            switch (m_filterOperator)
            {
            case FilterOperator.Not:
            case FilterOperator.IsNull:
            case FilterOperator.InView:
            case FilterOperator.OfType:
            {
                operandCount = 1;
                break;
            }

            case FilterOperator.And:
            case FilterOperator.Or:
            case FilterOperator.Equals:
            case FilterOperator.GreaterThan:
            case FilterOperator.GreaterThanOrEqual:
            case FilterOperator.LessThan:
            case FilterOperator.LessThanOrEqual:
            case FilterOperator.Like:
            case FilterOperator.Cast:
            {
                operandCount = 2;
                break;
            }

            case FilterOperator.Between:
            {
                operandCount = 3;
                break;
            }

            case FilterOperator.RelatedTo:
            {
                operandCount = 4;
                break;
            }

            case FilterOperator.InList:
            {
                operandCount = -1;
                break;
            }

            default:
            {
                break;
            }
            }

            if (operandCount != -1)
            {
                if (operandCount != m_filterOperands.Count)
                {
                    result.Status = ServiceResult.Create(
                        StatusCodes.BadEventFilterInvalid,
                        "ContentFilterElement does not have the correct number of operands (Operator={0} OperandCount={1}).",
                        m_filterOperator,
                        operandCount);

                    return(result);
                }
            }
            else
            {
                if (m_filterOperands.Count < 2)
                {
                    result.Status = ServiceResult.Create(
                        StatusCodes.BadEventFilterInvalid,
                        "ContentFilterElement does not have the correct number of operands (Operator={0} OperandCount={1}).",
                        m_filterOperator,
                        m_filterOperands.Count);

                    return(result);
                }
            }

            // validate the operands.
            bool error = false;

            for (int ii = 0; ii < m_filterOperands.Count; ii++)
            {
                ServiceResult operandResult = null;

                ExtensionObject operand = m_filterOperands[ii];

                // check for null.
                if (ExtensionObject.IsNull(operand))
                {
                    operandResult = ServiceResult.Create(
                        StatusCodes.BadEventFilterInvalid,
                        "The FilterOperand cannot be Null.");

                    result.OperandResults.Add(operandResult);
                    error = true;
                    continue;
                }

                // check that the extension object contains a filter operand.
                FilterOperand filterOperand = operand.Body  as FilterOperand;

                if (filterOperand == null)
                {
                    operandResult = ServiceResult.Create(
                        StatusCodes.BadEventFilterInvalid,
                        "The FilterOperand is not a supported type ({0}).",
                        filterOperand.GetType());

                    result.OperandResults.Add(operandResult);
                    error = true;
                    continue;
                }

                // validate the operand.
                filterOperand.Parent = this;
                operandResult        = filterOperand.Validate(context, index);

                if (ServiceResult.IsBad(operandResult))
                {
                    result.OperandResults.Add(operandResult);
                    error = true;
                    continue;
                }

                result.OperandResults.Add(null);
            }

            // ensure the global error code.
            if (error)
            {
                result.Status = StatusCodes.BadContentFilterInvalid;
            }
            else
            {
                result.OperandResults.Clear();
            }

            return(result);
        }