Amazon.DynamoDBv2.DocumentModel.Table.UpdateHelper C# (CSharp) Метод

        internal Document UpdateHelper(Document doc, Key key, UpdateItemOperationConfig config, bool isAsync)
        {
            var currentConfig = config ?? new UpdateItemOperationConfig();

            // If the keys have been changed, treat entire document as having changed
            bool haveKeysChanged = HaveKeysChanged(doc);
            bool updateChangedAttributesOnly = !haveKeysChanged;

            var attributeUpdates = doc.ToAttributeUpdateMap(Conversion, updateChangedAttributesOnly);
            foreach (var keyName in this.KeyNames)
            {
                attributeUpdates.Remove(keyName);
            }

            UpdateItemRequest req = new UpdateItemRequest
            {
                TableName = TableName,
                Key = key,
                AttributeUpdates = attributeUpdates.Count == 0 ? null : attributeUpdates, // pass null if keys-only update
                ReturnValues = EnumMapper.Convert(currentConfig.ReturnValues)
            };


            ((Amazon.Runtime.Internal.IAmazonWebServiceRequest)req).AddBeforeRequestHandler(isAsync ?
                new RequestEventHandler(UserAgentRequestEventHandlerAsync) :
                new RequestEventHandler(UserAgentRequestEventHandlerSync)
                );

            ValidateConditional(currentConfig);

            if (currentConfig.Expected != null)
            {
                req.Expected = currentConfig.Expected.ToExpectedAttributeMap(Conversion);
            }
            else if (currentConfig.ExpectedState != null &&
                currentConfig.ExpectedState.ExpectedValues != null &&
                currentConfig.ExpectedState.ExpectedValues.Count > 0)
            {
                req.Expected = currentConfig.ExpectedState.ToExpectedAttributeMap(Conversion);
                if (req.Expected.Count > 1)
                    req.ConditionalOperator = EnumMapper.Convert(currentConfig.ExpectedState.ConditionalOperator);
            }
            else if (currentConfig.ConditionalExpression != null && currentConfig.ConditionalExpression.IsSet)
            {
                currentConfig.ConditionalExpression.ApplyExpression(req, this.Conversion);

                string statement;
                Dictionary<string, AttributeValue> expressionAttributeValues;
                Dictionary<string, string> expressionAttributeNames;
                Common.ConvertAttributeUpdatesToUpdateExpression(attributeUpdates, out statement, out expressionAttributeValues, out expressionAttributeNames);

                req.AttributeUpdates = null;
                req.UpdateExpression = statement;

                if (req.ExpressionAttributeValues == null)
                    req.ExpressionAttributeValues = expressionAttributeValues;
                else
                {
                    foreach (var kvp in expressionAttributeValues)
                        req.ExpressionAttributeValues.Add(kvp.Key, kvp.Value);
                }

                if (req.ExpressionAttributeNames == null)
                    req.ExpressionAttributeNames = expressionAttributeNames;
                else
                {
                    foreach (var kvp in expressionAttributeNames)
                        req.ExpressionAttributeNames.Add(kvp.Key, kvp.Value);
                }
            }

            var resp = DDBClient.UpdateItem(req);
            var returnedAttributes = resp.Attributes;
            doc.CommitChanges();

            Document ret = null;
            if (currentConfig.ReturnValues != ReturnValues.None)
            {
                ret = Document.FromAttributeMap(returnedAttributes);
            }
            return ret;
        }