2021-12-02 15:10:47 -05:00
// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0
2022-12-20 11:23:09 -05:00
/**
* Before running this C++ code example, set up your development environment, including your credentials.
*
* For more information, see the following documentation topic:
*
* https://docs.aws.amazon.com/sdk-for-cpp/v1/developer-guide/getting-started.html
*
* For information on the structure of the code examples and how to build and run the examples, see
* https://docs.aws.amazon.com/sdk-for-cpp/v1/developer-guide/getting-started-code-examples.html.
*
**/
2021-12-02 15:10:47 -05:00
# include <aws/core/Aws.h>
# include <aws/dynamodb/DynamoDBClient.h>
# include <aws/dynamodb/model/AttributeDefinition.h>
# include <aws/dynamodb/model/QueryRequest.h>
# include <iostream>
2022-12-20 11:23:09 -05:00
# include "dynamodb_samples.h"
// snippet-start:[dynamodb.cpp.query_items.code]
//! Perform a query on an Amazon DynamoDB Table and retrieve items.
/*!
\sa queryItem()
\param tableName: The table name.
\param partitionKey: The partition key.
\param partitionValue: The value for the partition key.
\param projectionExpression: The projections expression, which is ignored if empty.
\param clientConfiguration: AWS client configuration.
\return bool: Function succeeded.
*/
2021-12-02 15:10:47 -05:00
2022-12-20 11:23:09 -05:00
/*
* The partition key attribute is searched with the specified value. By default, all fields and values
* contained in the item are returned. If an optional projection expression is
* specified on the command line, only the specified fields and values are
* returned.
*/
bool AwsDoc : : DynamoDB : : queryItems ( const Aws : : String & tableName ,
const Aws : : String & partitionKey ,
const Aws : : String & partitionValue ,
const Aws : : String & projectionExpression ,
const Aws : : Client : : ClientConfiguration & clientConfiguration ) {
Aws : : DynamoDB : : DynamoDBClient dynamoClient ( clientConfiguration ) ;
Aws : : DynamoDB : : Model : : QueryRequest request ;
request . SetTableName ( tableName ) ;
if ( ! projectionExpression . empty ( ) ) {
request . SetProjectionExpression ( projectionExpression ) ;
}
2021-12-02 15:10:47 -05:00
2022-12-20 11:23:09 -05:00
// Set query key condition expression.
request . SetKeyConditionExpression ( partitionKey + " = :valueToMatch " ) ;
// Set Expression AttributeValues.
Aws : : Map < Aws : : String , Aws : : DynamoDB : : Model : : AttributeValue > attributeValues ;
attributeValues . emplace ( " :valueToMatch " , partitionValue ) ;
request . SetExpressionAttributeValues ( attributeValues ) ;
bool result = true ;
// "exclusiveStartKey" is used for pagination.
Aws : : Map < Aws : : String , Aws : : DynamoDB : : Model : : AttributeValue > exclusiveStartKey ;
do {
if ( ! exclusiveStartKey . empty ( ) ) {
request . SetExclusiveStartKey ( exclusiveStartKey ) ;
exclusiveStartKey . clear ( ) ;
}
// Perform Query operation.
const Aws : : DynamoDB : : Model : : QueryOutcome & outcome = dynamoClient . Query ( request ) ;
if ( outcome . IsSuccess ( ) ) {
// Reference the retrieved items.
const Aws : : Vector < Aws : : Map < Aws : : String , Aws : : DynamoDB : : Model : : AttributeValue > > & items = outcome . GetResult ( ) . GetItems ( ) ;
if ( ! items . empty ( ) ) {
std : : cout < < " Number of items retrieved from Query: " < < items . size ( )
< < std : : endl ;
// Iterate each item and print.
for ( const auto & item : items ) {
std : : cout
< < " ****************************************************** "
< < std : : endl ;
// Output each retrieved field and its value.
for ( const auto & i : item )
std : : cout < < i . first < < " : " < < i . second . GetS ( ) < < std : : endl ;
}
}
else {
std : : cout < < " No item found in table: " < < tableName < < std : : endl ;
}
exclusiveStartKey = outcome . GetResult ( ) . GetLastEvaluatedKey ( ) ;
}
else {
std : : cerr < < " Failed to Query items: " < < outcome . GetError ( ) . GetMessage ( ) ;
result = false ;
break ;
}
} while ( ! exclusiveStartKey . empty ( ) ) ;
return result ;
}
// snippet-end:[dynamodb.cpp.query_items.code]
/*
* main function
*
* Usage: 'run_query_items <table_name> <partition_key> <partition_value> [projection_expression]'
*
* Prerequisites: Create a pre-populated DynamoDB table.
*
* For instructions on populating a table with sample data, see
* https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/SampleData.html.
*
*/
# ifndef TESTING_BUILD
int main ( int argc , char * * argv ) {
if ( argc < 4 ) {
std : : cout < < R " (
Usage :
run_query_items < table_name > < partition_key > < partition_value > [ projection_expression ]
Where :
table_name - The table to get an item from .
partition_key - The partition key attribute of the table .
partition_value - The partition key value to query .
[ projection_expression ] - The projection expression .
) " ;
2021-12-02 15:10:47 -05:00
return 1 ;
}
Aws : : SDKOptions options ;
Aws : : InitAPI ( options ) ;
{
2022-12-20 11:23:09 -05:00
const Aws : : String tableName = ( argv [ 1 ] ) ;
const Aws : : String partitionKey = ( argv [ 2 ] ) ;
const Aws : : String partitionValue = ( argv [ 3 ] ) ;
2021-12-02 15:10:47 -05:00
2022-12-20 11:23:09 -05:00
const Aws : : String projection ( argc > 4 ? argv [ 4 ] : " " ) ;
2021-12-02 15:10:47 -05:00
Aws : : Client : : ClientConfiguration clientConfig ;
2022-12-20 11:23:09 -05:00
// Optional: Set to the AWS Region (overrides config file).
// clientConfig.region = "us-east-1";
2021-12-02 15:10:47 -05:00
2022-12-20 11:23:09 -05:00
AwsDoc : : DynamoDB : : queryItems ( tableName , partitionKey , partitionValue , projection ,
clientConfig ) ;
2021-12-02 15:10:47 -05:00
}
Aws : : ShutdownAPI ( options ) ;
return 0 ;
2022-12-20 11:23:09 -05:00
}
# endif // TESTING_BUILD
