Opc.Ua.ContentFilter.RelatedTo C# (CSharp) Method

        private bool RelatedTo(FilterContext context, IFilterTarget target, ContentFilterElement element, NodeId intermediateNodeId)
        {
            // RelatedTo only supported in advanced filter targets.
            IAdvancedFilterTarget advancedTarget = target as IAdvancedFilterTarget;

            if (advancedTarget == null)
            {
                return false;
            }

            FilterOperand[] operands = GetOperands(element, 6);
            
            // get the type of the source.
            NodeId sourceTypeId = GetValue(context, operands[0], target) as NodeId;

            if (sourceTypeId == null)
            {
                return false;
            }
                        
            // get the type of reference to follow.
            NodeId referenceTypeId = GetValue(context, operands[2], target) as NodeId;

            if (referenceTypeId == null)
            {
                return false;
            }
            
            // get the number of hops
            int? hops = 1;

            object hopsValue = GetValue(context, operands[3], target);

            if (hopsValue != null)
            {
                hops = Cast(hopsValue, BuiltInType.Int32) as int?;

                if (hops == null)
                {
                    hops = 1;
                }
            }

            // get whether to include type definition subtypes.
            bool? includeTypeDefinitionSubtypes = true;

            object includeValue = GetValue(context, operands[4], target);

            if (includeValue != null)
            {
                includeTypeDefinitionSubtypes = Cast(includeValue, BuiltInType.Boolean) as bool?;

                if (includeTypeDefinitionSubtypes == null)
                {
                    includeTypeDefinitionSubtypes = true;
                }
            }

            // get whether to include reference type subtypes.
            bool? includeReferenceTypeSubtypes = true;

            includeValue = GetValue(context, operands[5], target);

            if (includeValue != null)
            {
                includeReferenceTypeSubtypes = Cast(includeValue, BuiltInType.Boolean) as bool?;

                if (includeReferenceTypeSubtypes == null)
                {
                    includeReferenceTypeSubtypes = true;
                }
            }

            NodeId targetTypeId = null;

            // check if elements are chained.
            ElementOperand chainedOperand = operands[1] as ElementOperand;

            if (chainedOperand != null)
            {
                if (chainedOperand.Index < 0 || chainedOperand.Index >= Elements.Count)
                {
                    return false;
                }

                ContentFilterElement chainedElement = Elements[(int)chainedOperand.Index];

                // get the target type from the first operand of the chained element.
                if (chainedElement.FilterOperator == FilterOperator.RelatedTo)
                {
                    FilterOperand nestedType = ExtensionObject.ToEncodeable(chainedElement.FilterOperands[0]) as FilterOperand;

                    targetTypeId = GetValue(context, nestedType, target) as NodeId;

                    if (targetTypeId == null)
                    {
                        return false;
                    }

                    // find the nodes that meet the criteria in the first link of the chain.
                    IList<NodeId> nodeIds = advancedTarget.GetRelatedNodes(
                        context,
                        intermediateNodeId,
                        sourceTypeId,
                        targetTypeId,
                        referenceTypeId,
                        hops.Value,
                        includeTypeDefinitionSubtypes.Value,
                        includeReferenceTypeSubtypes.Value);

                    if (nodeIds == null || nodeIds.Count == 0)
                    {
                        return false;
                    }
                    
                    // recursively follow the chain.
                    for (int ii = 0; ii < nodeIds.Count; ii++)
                    {
                        // one match is all that is required.
                        if (RelatedTo(context, target, chainedElement, nodeIds[ii]))
                        {
                            return true;
                        }
                    }

                    // no matches.
                    return false;
                }
            }
            
            // get the type of the target.
            if (targetTypeId == null)
            {
                targetTypeId = GetValue(context, operands[1], target) as NodeId;

                if (targetTypeId == null)
                {
                    return false;
                }
            }

            // check the target.            
            try
            {
                bool relatedTo = advancedTarget.IsRelatedTo(
                    context,
                    intermediateNodeId,
                    sourceTypeId,
                    targetTypeId,
                    referenceTypeId,
                    hops.Value,
                    includeTypeDefinitionSubtypes.Value,
                    includeReferenceTypeSubtypes.Value);

                return relatedTo;
            }
            catch
            {
                return false;
            }
        }
        #endregion