C
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 C Downloads
#include <C_CkRest.h>
#include <C_CkAuthAws.h>
#include <C_CkJsonObject.h>
#include <C_CkStringBuilder.h>
void ChilkatSample(void)
{
BOOL success;
HCkRest rest;
HCkAuthAws authAws;
BOOL bTls;
int port;
BOOL bAutoReconnect;
HCkJsonObject json;
HCkStringBuilder sbRequestBody;
HCkStringBuilder sbResponseBody;
int respStatusCode;
HCkJsonObject jsonResponse;
const char *strVal;
const char *AttributesLastPostedByS;
const char *AttributesForumNameS;
const char *AttributesLastPostDateTimeS;
const char *AttributesSubjectS;
const char *AttributesViewsN;
const char *AttributesMessageS;
int i;
int count_i;
success = FALSE;
rest = CkRest_Create();
// 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
authAws = CkAuthAws_Create();
CkAuthAws_putAccessKey(authAws,"AWS_ACCESS_KEY");
CkAuthAws_putSecretKey(authAws,"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.)
CkAuthAws_putRegion(authAws,"us-west-2");
CkAuthAws_putServiceName(authAws,"dynamodb");
// SetAuthAws causes Chilkat to automatically add the following headers: Authorization, X-Amz-Date
CkRest_SetAuthAws(rest,authAws);
// URL: https://dynamodb.us-west-2.amazonaws.com/
bTls = TRUE;
port = 443;
bAutoReconnect = TRUE;
success = CkRest_Connect(rest,"dynamodb.us-west-2.amazonaws.com",port,bTls,bAutoReconnect);
if (success != TRUE) {
printf("ConnectFailReason: %d\n",CkRest_getConnectFailReason(rest));
printf("%s\n",CkRest_lastErrorText(rest));
CkRest_Dispose(rest);
CkAuthAws_Dispose(authAws);
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"
// }
json = CkJsonObject_Create();
CkJsonObject_UpdateString(json,"TableName","Thread");
CkJsonObject_UpdateString(json,"Key.ForumName.S","Amazon DynamoDB");
CkJsonObject_UpdateString(json,"Key.Subject.S","Maximum number of items?");
CkJsonObject_UpdateString(json,"UpdateExpression","set LastPostedBy = :val1");
CkJsonObject_UpdateString(json,"ConditionExpression","LastPostedBy = :val2");
CkJsonObject_UpdateString(json,"ExpressionAttributeValues.:val1.S","alice@example.com");
CkJsonObject_UpdateString(json,"ExpressionAttributeValues.:val2.S","fred@example.com");
CkJsonObject_UpdateString(json,"ReturnValues","ALL_NEW");
CkRest_AddHeader(rest,"Content-Type","application/x-amz-json-1.0");
CkRest_AddHeader(rest,"X-Amz-Target","DynamoDB_20120810.UpdateItem");
CkRest_AddHeader(rest,"Accept-Encoding","identity");
sbRequestBody = CkStringBuilder_Create();
CkJsonObject_EmitSb(json,sbRequestBody);
sbResponseBody = CkStringBuilder_Create();
success = CkRest_FullRequestSb(rest,"POST","/",sbRequestBody,sbResponseBody);
if (success != TRUE) {
printf("%s\n",CkRest_lastErrorText(rest));
CkRest_Dispose(rest);
CkAuthAws_Dispose(authAws);
CkJsonObject_Dispose(json);
CkStringBuilder_Dispose(sbRequestBody);
CkStringBuilder_Dispose(sbResponseBody);
return;
}
respStatusCode = CkRest_getResponseStatusCode(rest);
printf("response status code = %d\n",respStatusCode);
if (respStatusCode >= 400) {
printf("Response Status Code = %d\n",respStatusCode);
printf("Response Header:\n");
printf("%s\n",CkRest_responseHeader(rest));
printf("Response Body:\n");
printf("%s\n",CkStringBuilder_getAsString(sbResponseBody));
CkRest_Dispose(rest);
CkAuthAws_Dispose(authAws);
CkJsonObject_Dispose(json);
CkStringBuilder_Dispose(sbRequestBody);
CkStringBuilder_Dispose(sbResponseBody);
return;
}
jsonResponse = CkJsonObject_Create();
CkJsonObject_LoadSb(jsonResponse,sbResponseBody);
CkJsonObject_putEmitCompact(jsonResponse,FALSE);
printf("%s\n",CkJsonObject_emit(jsonResponse));
// 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
AttributesLastPostedByS = CkJsonObject_stringOf(jsonResponse,"Attributes.LastPostedBy.S");
AttributesForumNameS = CkJsonObject_stringOf(jsonResponse,"Attributes.ForumName.S");
AttributesLastPostDateTimeS = CkJsonObject_stringOf(jsonResponse,"Attributes.LastPostDateTime.S");
AttributesSubjectS = CkJsonObject_stringOf(jsonResponse,"Attributes.Subject.S");
AttributesViewsN = CkJsonObject_stringOf(jsonResponse,"Attributes.Views.N");
AttributesMessageS = CkJsonObject_stringOf(jsonResponse,"Attributes.Message.S");
i = 0;
count_i = CkJsonObject_SizeOfArray(jsonResponse,"Attributes.Tags.SS");
while (i < count_i) {
CkJsonObject_putI(jsonResponse,i);
strVal = CkJsonObject_stringOf(jsonResponse,"Attributes.Tags.SS[i]");
i = i + 1;
}
CkRest_Dispose(rest);
CkAuthAws_Dispose(authAws);
CkJsonObject_Dispose(json);
CkStringBuilder_Dispose(sbRequestBody);
CkStringBuilder_Dispose(sbResponseBody);
CkJsonObject_Dispose(jsonResponse);
}