다음 C# 코드 예제는 Amazon DynamoDB 항목에 대한 CRUD 작업을 보여줍니다. 여기 예제에서는 항목을 ProductCatalog 테이블에 추가하고, 항목을 가져오고, 다수의 업데이트를 실행하고, 그리고 마지막으로 항목을 삭제합니다. 이 테이블을 만들지 않은 경우 프로그래밍 방식으로 만들 수도 있습니다. 자세한 내용은 AWS SDK for .NET를 사용한 예시 테이블 생성 및 데이터 업로드 단원을 참조하십시오.
다음 샘플을 테스트하기 위한 단계별 지침은 .NET 코드 예시 섹션을 참조하세요.
예
using System;
using System.Collections.Generic;
using Amazon.DynamoDBv2;
using Amazon.DynamoDBv2.Model;
using Amazon.Runtime;
using Amazon.SecurityToken;
namespace com.amazonaws.codesamples
{
class LowLevelItemCRUDExample
{
private static string tableName = "ProductCatalog";
private static AmazonDynamoDBClient client = new AmazonDynamoDBClient();
static void Main(string[] args)
{
try
{
CreateItem();
RetrieveItem();
// Perform various updates.
UpdateMultipleAttributes();
UpdateExistingAttributeConditionally();
// Delete item.
DeleteItem();
Console.WriteLine("To continue, press Enter");
Console.ReadLine();
}
catch (Exception e)
{
Console.WriteLine(e.Message);
Console.WriteLine("To continue, press Enter");
Console.ReadLine();
}
}
private static void CreateItem()
{
var request = new PutItemRequest
{
TableName = tableName,
Item = new Dictionary<string, AttributeValue>()
{
{ "Id", new AttributeValue {
N = "1000"
}},
{ "Title", new AttributeValue {
S = "Book 201 Title"
}},
{ "ISBN", new AttributeValue {
S = "11-11-11-11"
}},
{ "Authors", new AttributeValue {
SS = new List<string>{"Author1", "Author2" }
}},
{ "Price", new AttributeValue {
N = "20.00"
}},
{ "Dimensions", new AttributeValue {
S = "8.5x11.0x.75"
}},
{ "InPublication", new AttributeValue {
BOOL = false
} }
}
};
client.PutItem(request);
}
private static void RetrieveItem()
{
var request = new GetItemRequest
{
TableName = tableName,
Key = new Dictionary<string, AttributeValue>()
{
{ "Id", new AttributeValue {
N = "1000"
} }
},
ProjectionExpression = "Id, ISBN, Title, Authors",
ConsistentRead = true
};
var response = client.GetItem(request);
// Check the response.
var attributeList = response.Item; // attribute list in the response.
Console.WriteLine("\nPrinting item after retrieving it ............");
PrintItem(attributeList);
}
private static void UpdateMultipleAttributes()
{
var request = new UpdateItemRequest
{
Key = new Dictionary<string, AttributeValue>()
{
{ "Id", new AttributeValue {
N = "1000"
} }
},
// Perform the following updates:
// 1) Add two new authors to the list
// 1) Set a new attribute
// 2) Remove the ISBN attribute
ExpressionAttributeNames = new Dictionary<string, string>()
{
{"#A","Authors"},
{"#NA","NewAttribute"},
{"#I","ISBN"}
},
ExpressionAttributeValues = new Dictionary<string, AttributeValue>()
{
{":auth",new AttributeValue {
SS = {"Author YY", "Author ZZ"}
}},
{":new",new AttributeValue {
S = "New Value"
}}
},
UpdateExpression = "ADD #A :auth SET #NA = :new REMOVE #I",
TableName = tableName,
ReturnValues = "ALL_NEW" // Give me all attributes of the updated item.
};
var response = client.UpdateItem(request);
// Check the response.
var attributeList = response.Attributes; // attribute list in the response.
// print attributeList.
Console.WriteLine("\nPrinting item after multiple attribute update ............");
PrintItem(attributeList);
}
private static void UpdateExistingAttributeConditionally()
{
var request = new UpdateItemRequest
{
Key = new Dictionary<string, AttributeValue>()
{
{ "Id", new AttributeValue {
N = "1000"
} }
},
ExpressionAttributeNames = new Dictionary<string, string>()
{
{"#P", "Price"}
},
ExpressionAttributeValues = new Dictionary<string, AttributeValue>()
{
{":newprice",new AttributeValue {
N = "22.00"
}},
{":currprice",new AttributeValue {
N = "20.00"
}}
},
// This updates price only if current price is 20.00.
UpdateExpression = "SET #P = :newprice",
ConditionExpression = "#P = :currprice",
TableName = tableName,
ReturnValues = "ALL_NEW" // Give me all attributes of the updated item.
};
var response = client.UpdateItem(request);
// Check the response.
var attributeList = response.Attributes; // attribute list in the response.
Console.WriteLine("\nPrinting item after updating price value conditionally ............");
PrintItem(attributeList);
}
private static void DeleteItem()
{
var request = new DeleteItemRequest
{
TableName = tableName,
Key = new Dictionary<string, AttributeValue>()
{
{ "Id", new AttributeValue {
N = "1000"
} }
},
// Return the entire item as it appeared before the update.
ReturnValues = "ALL_OLD",
ExpressionAttributeNames = new Dictionary<string, string>()
{
{"#IP", "InPublication"}
},
ExpressionAttributeValues = new Dictionary<string, AttributeValue>()
{
{":inpub",new AttributeValue {
BOOL = false
}}
},
ConditionExpression = "#IP = :inpub"
};
var response = client.DeleteItem(request);
// Check the response.
var attributeList = response.Attributes; // Attribute list in the response.
// Print item.
Console.WriteLine("\nPrinting item that was just deleted ............");
PrintItem(attributeList);
}
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("************************************************");
}
}
}
