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LowLevelQuery.cs

/** * Copyright 2010-2019 Amazon.com, Inc. or its affiliates. All Rights Reserved. * * This file is licensed under the Apache License, Version 2.0 (the "License"). * You may not use this file except in compliance with the License. A copy of * the License is located at * * http://aws.amazon.com/apache2.0/ * * This file is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR * CONDITIONS OF ANY KIND, either express or implied. See the License for the * specific language governing permissions and limitations under the License. */ using System; using System.Collections.Generic; using Amazon.DynamoDBv2; using Amazon.DynamoDBv2.Model; using Amazon.Runtime; using Amazon.Util; namespace com.amazonaws.codesamples { class LowLevelQuery { private static AmazonDynamoDBClient client = new AmazonDynamoDBClient(); static void Main(string[] args) { try { // Query a specific forum and thread. string forumName = "Amazon DynamoDB"; string threadSubject = "DynamoDB Thread 1"; FindRepliesForAThread(forumName, threadSubject); FindRepliesForAThreadSpecifyOptionalLimit(forumName, threadSubject); FindRepliesInLast15DaysWithConfig(forumName, threadSubject); FindRepliesPostedWithinTimePeriod(forumName, threadSubject); Console.WriteLine("Example complete. To continue, press Enter"); Console.ReadLine(); } catch (AmazonDynamoDBException e) { Console.WriteLine(e.Message); Console.ReadLine(); } catch (AmazonServiceException e) { Console.WriteLine(e.Message); Console.ReadLine(); } catch (Exception e) { Console.WriteLine(e.Message); Console.ReadLine(); } } private static void FindRepliesPostedWithinTimePeriod(string forumName, string threadSubject) { Console.WriteLine("*** Executing FindRepliesPostedWithinTimePeriod() ***"); string replyId = forumName + "#" + threadSubject; // You must provide date value based on your test data. DateTime startDate = DateTime.UtcNow - TimeSpan.FromDays(21); string start = startDate.ToString(AWSSDKUtils.ISO8601DateFormat); // You provide date value based on your test data. DateTime endDate = DateTime.UtcNow - TimeSpan.FromDays(5); string end = endDate.ToString(AWSSDKUtils.ISO8601DateFormat); var request = new QueryRequest { TableName = "Reply", ReturnConsumedCapacity = "TOTAL", KeyConditionExpression = "Id = :v_replyId and ReplyDateTime between :v_start and :v_end", ExpressionAttributeValues = new Dictionary<string, AttributeValue> { {":v_replyId", new AttributeValue { S = replyId }}, {":v_start", new AttributeValue { S = start }}, {":v_end", new AttributeValue { S = end }} } }; var response = client.Query(request); Console.WriteLine("\nNo. of reads used (by query in FindRepliesPostedWithinTimePeriod) {0}", response.ConsumedCapacity.CapacityUnits); foreach (Dictionary<string, AttributeValue> item in response.Items) { PrintItem(item); } Console.WriteLine("To continue, press Enter"); Console.ReadLine(); } private static void FindRepliesInLast15DaysWithConfig(string forumName, string threadSubject) { Console.WriteLine("*** Executing FindRepliesInLast15DaysWithConfig() ***"); string replyId = forumName + "#" + threadSubject; DateTime twoWeeksAgoDate = DateTime.UtcNow - TimeSpan.FromDays(15); string twoWeeksAgoString = twoWeeksAgoDate.ToString(AWSSDKUtils.ISO8601DateFormat); var request = new QueryRequest { TableName = "Reply", ReturnConsumedCapacity = "TOTAL", KeyConditionExpression = "Id = :v_replyId and ReplyDateTime > :v_interval", ExpressionAttributeValues = new Dictionary<string, AttributeValue> { {":v_replyId", new AttributeValue { S = replyId }}, {":v_interval", new AttributeValue { S = twoWeeksAgoString }} }, // Optional parameter. ProjectionExpression = "Id, ReplyDateTime, PostedBy", // Optional parameter. ConsistentRead = true }; var response = client.Query(request); Console.WriteLine("No. of reads used (by query in FindRepliesInLast15DaysWithConfig) {0}", response.ConsumedCapacity.CapacityUnits); foreach (Dictionary<string, AttributeValue> item in response.Items) { PrintItem(item); } Console.WriteLine("To continue, press Enter"); Console.ReadLine(); } private static void FindRepliesForAThreadSpecifyOptionalLimit(string forumName, string threadSubject) { Console.WriteLine("*** Executing FindRepliesForAThreadSpecifyOptionalLimit() ***"); string replyId = forumName + "#" + threadSubject; Dictionary<string, AttributeValue> lastKeyEvaluated = null; do { var request = new QueryRequest { TableName = "Reply", ReturnConsumedCapacity = "TOTAL", KeyConditionExpression = "Id = :v_replyId", ExpressionAttributeValues = new Dictionary<string, AttributeValue> { {":v_replyId", new AttributeValue { S = replyId }} }, Limit = 2, // The Reply table has only a few sample items. So the page size is smaller. ExclusiveStartKey = lastKeyEvaluated }; var response = client.Query(request); Console.WriteLine("No. of reads used (by query in FindRepliesForAThreadSpecifyLimit) {0}\n", response.ConsumedCapacity.CapacityUnits); foreach (Dictionary<string, AttributeValue> item in response.Items) { PrintItem(item); } lastKeyEvaluated = response.LastEvaluatedKey; } while (lastKeyEvaluated != null && lastKeyEvaluated.Count != 0); Console.WriteLine("To continue, press Enter"); Console.ReadLine(); } private static void FindRepliesForAThread(string forumName, string threadSubject) { Console.WriteLine("*** Executing FindRepliesForAThread() ***"); string replyId = forumName + "#" + threadSubject; var request = new QueryRequest { TableName = "Reply", ReturnConsumedCapacity = "TOTAL", KeyConditionExpression = "Id = :v_replyId", ExpressionAttributeValues = new Dictionary<string, AttributeValue> { {":v_replyId", new AttributeValue { S = replyId }} } }; var response = client.Query(request); Console.WriteLine("No. of reads used (by query in FindRepliesForAThread) {0}\n", response.ConsumedCapacity.CapacityUnits); foreach (Dictionary<string, AttributeValue> item in response.Items) { PrintItem(item); } Console.WriteLine("To continue, press Enter"); Console.ReadLine(); } private static void PrintItem( Dictionary<string, AttributeValue> attributeList) { foreach (KeyValuePair<string, AttributeValue> kvp in attributeList) { string attributeName = kvp.Key; AttributeValue value = kvp.Value; Console.WriteLine( attributeName + " " + (value.S == null ? "" : "S=[" + value.S + "]") + (value.N == null ? "" : "N=[" + value.N + "]") + (value.SS == null ? "" : "SS=[" + string.Join(",", value.SS.ToArray()) + "]") + (value.NS == null ? "" : "NS=[" + string.Join(",", value.NS.ToArray()) + "]") ); } Console.WriteLine("************************************************"); } } }

Sample Details

Service: dynamodb

Last tested:

Author: AWS

Type: full-example

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