Welcome to the AWS Code Examples Repository. This repo contains code examples used in the AWS documentation, AWS SDK Developer Guides, and more. For more information, see the Readme.md file below.
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//snippet-sourcedescription:[query_items.cpp demonstrates how to perfrom Query operation and retrieve items from an Amazon DynamoDB table.]
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//snippet-keyword:[AWS SDK for C++]
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//snippet-keyword:[Code Sample]
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//snippet-service:[Amazon DynamoDB]
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//snippet-sourcetype:[full-example]
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//snippet-sourcedate:[11/30/2021]
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//snippet-sourceauthor:[scmacdon - aws]
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/*
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Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
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SPDX-License-Identifier: Apache-2.0
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*/
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//snippet-start:[dynamodb.cpp.query_items.inc]
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#include <aws/core/Aws.h>
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#include <aws/core/utils/Outcome.h>
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#include <aws/dynamodb/DynamoDBClient.h>
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#include <aws/dynamodb/model/AttributeDefinition.h>
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#include <aws/dynamodb/model/QueryRequest.h>
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#include <iostream>
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//snippet-end:[dynamodb.cpp.query_items.inc]
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/**
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Perform query on a DynamoDB Table and retrieve item(s).
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The partition key attribute is searched with the specified value. By default, all fields and values
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contained in the item are returned. If an optional projection expression is
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specified on the command line, only the specified fields and values are
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returned.
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To run this C++ code example, ensure that you have setup your development environment, including your credentials.
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For information, see this documentation topic:
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https://docs.aws.amazon.com/sdk-for-cpp/v1/developer-guide/getting-started.html
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*/
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int main(int argc, char** argv)
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{
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const std::string USAGE = "\n" \
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"Usage:\n"
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" query_items <table> <partitionKeyAttributeName>=<partitionKeyValue> [projection_expression]\n\n"
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"Where:\n"
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" table - the table to get an item from.\n"
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" partitionKeyAttributeName - Partition Key attribute of the table.\n"
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" partitionKeyValue - Partition Key value to query.\n\n"
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"Example:\n"
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" query_items HelloTable Name=Namaste\n"
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" query_items Players FirstName=Mike\n"
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" query_items SiteColors Background=white \"default, bold\"\n";
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if (argc < 2)
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{
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std::cout << USAGE;
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return 1;
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}
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Aws::SDKOptions options;
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Aws::InitAPI(options);
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{
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const Aws::String table = (argv[1]);
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const Aws::String partitionKeyNameAndValue = (argv[2]);
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Aws::String partitionKeyAttributeName("");
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Aws::String partitionKeyAttributeValue("");
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// Split and get partitionKeyAttributeName and partitionKeyAttributeValue
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const Aws::Vector<Aws::String>& flds = Aws::Utils::StringUtils::Split(partitionKeyNameAndValue, '=');
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if (flds.size() == 2)
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{
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partitionKeyAttributeName = flds[0];
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partitionKeyAttributeValue = flds[1];
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}
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else
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{
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std::cout << "Invalid argument: " << partitionKeyNameAndValue << std::endl << USAGE;
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return 1;
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}
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const Aws::String projection(argc > 3 ? argv[3] : "");
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// snippet-start:[dynamodb.cpp.query_items.code]
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Aws::Client::ClientConfiguration clientConfig;
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Aws::DynamoDB::DynamoDBClient dynamoClient(clientConfig);
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Aws::DynamoDB::Model::QueryRequest req;
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req.SetTableName(table);
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// Set query key condition expression
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req.SetKeyConditionExpression(partitionKeyAttributeName + "= :valueToMatch");
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// Set Expression AttributeValues
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Aws::Map<Aws::String, Aws::DynamoDB::Model::AttributeValue> attributeValues;
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attributeValues.emplace(":valueToMatch", partitionKeyAttributeValue);
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req.SetExpressionAttributeValues(attributeValues);
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// Perform Query operation
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const Aws::DynamoDB::Model::QueryOutcome& result = dynamoClient.Query(req);
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if (result.IsSuccess())
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{
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// Reference the retrieved items
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const Aws::Vector<Aws::Map<Aws::String, Aws::DynamoDB::Model::AttributeValue>>& items = result.GetResult().GetItems();
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if(items.size() > 0)
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{
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std::cout << "Number of items retrieved from Query: " << items.size() << std::endl;
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//Iterate each item and print
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for(const auto &item: items)
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{
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std::cout << "******************************************************" << std::endl;
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// Output each retrieved field and its value
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for (const auto& i : item)
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std::cout << i.first << ": " << i.second.GetS() << std::endl;
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}
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}
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else
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{
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std::cout << "No item found in table: " << table << std::endl;
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}
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}
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else
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{
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std::cout << "Failed to Query items: " << result.GetError().GetMessage();
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}
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// snippet-end:[dynamodb.cpp.query_items.code]
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}
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Aws::ShutdownAPI(options);
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return 0;
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}
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