Unicode C++
Unicode C++
DynamoDB - UpdateItem
See more Amazon DynamoDB Examples
Edits an existing item's attributes, or adds a new item to the table if it does not already exist. You can put, delete, or add attribute values. You can also perform a conditional update on an existing item (insert a new attribute name-value pair if it doesn't exist, or replace an existing name-value pair if it has certain expected attribute values).Chilkat Unicode C++ Downloads
#include <CkRestW.h>
#include <CkAuthAwsW.h>
#include <CkJsonObjectW.h>
#include <CkStringBuilderW.h>
void ChilkatSample(void)
{
bool success = false;
CkRestW rest;
// Implements the following CURL command:
// curl -X POST https://dynamodb.us-west-2.amazonaws.com/ \
// -H "Accept-Encoding: identity" \
// -H "Content-Type: application/x-amz-json-1.0" \
// -H "Authorization: AWS4-HMAC-SHA256 Credential=<Credential>, SignedHeaders=<Headers>, Signature=<Signature>" \
// -H "X-Amz-Date: <Date>" \
// -H "X-Amz-Target: DynamoDB_20120810.UpdateItem" \
// -d '{
// "TableName": "Thread",
// "Key": {
// "ForumName": {
// "S": "Amazon DynamoDB"
// },
// "Subject": {
// "S": "Maximum number of items?"
// }
// },
// "UpdateExpression": "set LastPostedBy = :val1",
// "ConditionExpression": "LastPostedBy = :val2",
// "ExpressionAttributeValues": {
// ":val1": {"S": "alice@example.com"},
// ":val2": {"S": "fred@example.com"}
// },
// "ReturnValues": "ALL_NEW"
// }'
// Use the following online tool to generate REST code from a CURL command
// Convert a cURL Command to REST Source Code
CkAuthAwsW authAws;
authAws.put_AccessKey(L"AWS_ACCESS_KEY");
authAws.put_SecretKey(L"AWS_SECRET_KEY");
// Don't forget to change the region to your particular region. (Also make the same change in the call to Connect below.)
authAws.put_Region(L"us-west-2");
authAws.put_ServiceName(L"dynamodb");
// SetAuthAws causes Chilkat to automatically add the following headers: Authorization, X-Amz-Date
rest.SetAuthAws(authAws);
// URL: https://dynamodb.us-west-2.amazonaws.com/
bool bTls = true;
int port = 443;
bool bAutoReconnect = true;
success = rest.Connect(L"dynamodb.us-west-2.amazonaws.com",port,bTls,bAutoReconnect);
if (success != true) {
wprintf(L"ConnectFailReason: %d\n",rest.get_ConnectFailReason());
wprintf(L"%s\n",rest.lastErrorText());
return;
}
// Note: The above code does not need to be repeatedly called for each REST request.
// The rest object can be setup once, and then many requests can be sent. Chilkat will automatically
// reconnect within a FullRequest* method as needed. It is only the very first connection that is explicitly
// made via the Connect method.
// Use this online tool to generate code from sample JSON:
// Generate Code to Create JSON
// The following JSON is sent in the request body.
// {
// "TableName": "Thread",
// "Key": {
// "ForumName": {
// "S": "Amazon DynamoDB"
// },
// "Subject": {
// "S": "Maximum number of items?"
// }
// },
// "UpdateExpression": "set LastPostedBy = :val1",
// "ConditionExpression": "LastPostedBy = :val2",
// "ExpressionAttributeValues": {
// ":val1": {
// "S": "alice@example.com"
// },
// ":val2": {
// "S": "fred@example.com"
// }
// },
// "ReturnValues": "ALL_NEW"
// }
CkJsonObjectW json;
json.UpdateString(L"TableName",L"Thread");
json.UpdateString(L"Key.ForumName.S",L"Amazon DynamoDB");
json.UpdateString(L"Key.Subject.S",L"Maximum number of items?");
json.UpdateString(L"UpdateExpression",L"set LastPostedBy = :val1");
json.UpdateString(L"ConditionExpression",L"LastPostedBy = :val2");
json.UpdateString(L"ExpressionAttributeValues.:val1.S",L"alice@example.com");
json.UpdateString(L"ExpressionAttributeValues.:val2.S",L"fred@example.com");
json.UpdateString(L"ReturnValues",L"ALL_NEW");
rest.AddHeader(L"Content-Type",L"application/x-amz-json-1.0");
rest.AddHeader(L"X-Amz-Target",L"DynamoDB_20120810.UpdateItem");
rest.AddHeader(L"Accept-Encoding",L"identity");
CkStringBuilderW sbRequestBody;
json.EmitSb(sbRequestBody);
CkStringBuilderW sbResponseBody;
success = rest.FullRequestSb(L"POST",L"/",sbRequestBody,sbResponseBody);
if (success != true) {
wprintf(L"%s\n",rest.lastErrorText());
return;
}
int respStatusCode = rest.get_ResponseStatusCode();
wprintf(L"response status code = %d\n",respStatusCode);
if (respStatusCode >= 400) {
wprintf(L"Response Status Code = %d\n",respStatusCode);
wprintf(L"Response Header:\n");
wprintf(L"%s\n",rest.responseHeader());
wprintf(L"Response Body:\n");
wprintf(L"%s\n",sbResponseBody.getAsString());
return;
}
CkJsonObjectW jsonResponse;
jsonResponse.LoadSb(sbResponseBody);
jsonResponse.put_EmitCompact(false);
wprintf(L"%s\n",jsonResponse.emit());
// Sample JSON response:
// (Sample code for parsing the JSON response is shown below)
// {
// "Attributes": {
// "LastPostedBy": {
// "S": "alice@example.com"
// },
// "ForumName": {
// "S": "Amazon DynamoDB"
// },
// "LastPostDateTime": {
// "S": "20130320010350"
// },
// "Tags": {
// "SS": [
// "Update",
// "Multiple Items",
// "HelpMe"
// ]
// },
// "Subject": {
// "S": "Maximum number of items?"
// },
// "Views": {
// "N": "5"
// },
// "Message": {
// "S": "I want to put 10 million data items to an Amazon DynamoDB table. Is there an upper limit?"
// }
// }
// }
// Sample code for parsing the JSON response...
// Use the following online tool to generate parsing code from sample JSON:
// Generate Parsing Code from JSON
const wchar_t *strVal = 0;
const wchar_t *AttributesLastPostedByS = jsonResponse.stringOf(L"Attributes.LastPostedBy.S");
const wchar_t *AttributesForumNameS = jsonResponse.stringOf(L"Attributes.ForumName.S");
const wchar_t *AttributesLastPostDateTimeS = jsonResponse.stringOf(L"Attributes.LastPostDateTime.S");
const wchar_t *AttributesSubjectS = jsonResponse.stringOf(L"Attributes.Subject.S");
const wchar_t *AttributesViewsN = jsonResponse.stringOf(L"Attributes.Views.N");
const wchar_t *AttributesMessageS = jsonResponse.stringOf(L"Attributes.Message.S");
int i = 0;
int count_i = jsonResponse.SizeOfArray(L"Attributes.Tags.SS");
while (i < count_i) {
jsonResponse.put_I(i);
strVal = jsonResponse.stringOf(L"Attributes.Tags.SS[i]");
i = i + 1;
}
}