(.NET Core C#) DynamoDB - UpdateItem

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).

For more information, see https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_UpdateItem.html

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Chilkat.Rest rest = new Chilkat.Rest();
bool success;

// 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

Chilkat.AuthAws authAws = new Chilkat.AuthAws();
authAws.AccessKey = "AWS_ACCESS_KEY";
authAws.SecretKey = "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.Region = "us-west-2";
authAws.ServiceName = "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("dynamodb.us-west-2.amazonaws.com",port,bTls,bAutoReconnect);
if (success != true) {
    Debug.WriteLine("ConnectFailReason: " + Convert.ToString(rest.ConnectFailReason));
    Debug.WriteLine(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"
// }

Chilkat.JsonObject json = new Chilkat.JsonObject();
json.UpdateString("TableName","Thread");
json.UpdateString("Key.ForumName.S","Amazon DynamoDB");
json.UpdateString("Key.Subject.S","Maximum number of items?");
json.UpdateString("UpdateExpression","set LastPostedBy = :val1");
json.UpdateString("ConditionExpression","LastPostedBy = :val2");
json.UpdateString("ExpressionAttributeValues.:val1.S","alice@example.com");
json.UpdateString("ExpressionAttributeValues.:val2.S","fred@example.com");
json.UpdateString("ReturnValues","ALL_NEW");

rest.AddHeader("Content-Type","application/x-amz-json-1.0");
rest.AddHeader("X-Amz-Target","DynamoDB_20120810.UpdateItem");
rest.AddHeader("Accept-Encoding","identity");

Chilkat.StringBuilder sbRequestBody = new Chilkat.StringBuilder();
json.EmitSb(sbRequestBody);
Chilkat.StringBuilder sbResponseBody = new Chilkat.StringBuilder();
success = rest.FullRequestSb("POST","/",sbRequestBody,sbResponseBody);
if (success != true) {
    Debug.WriteLine(rest.LastErrorText);
    return;
}

int respStatusCode = rest.ResponseStatusCode;
Debug.WriteLine("response status code = " + Convert.ToString(respStatusCode));
if (respStatusCode >= 400) {
    Debug.WriteLine("Response Status Code = " + Convert.ToString(respStatusCode));
    Debug.WriteLine("Response Header:");
    Debug.WriteLine(rest.ResponseHeader);
    Debug.WriteLine("Response Body:");
    Debug.WriteLine(sbResponseBody.GetAsString());
    return;
}

Chilkat.JsonObject jsonResponse = new Chilkat.JsonObject();
jsonResponse.LoadSb(sbResponseBody);

jsonResponse.EmitCompact = false;
Debug.WriteLine(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

string strVal;

string AttributesLastPostedByS = jsonResponse.StringOf("Attributes.LastPostedBy.S");
string AttributesForumNameS = jsonResponse.StringOf("Attributes.ForumName.S");
string AttributesLastPostDateTimeS = jsonResponse.StringOf("Attributes.LastPostDateTime.S");
string AttributesSubjectS = jsonResponse.StringOf("Attributes.Subject.S");
string AttributesViewsN = jsonResponse.StringOf("Attributes.Views.N");
string AttributesMessageS = jsonResponse.StringOf("Attributes.Message.S");
int i = 0;
int count_i = jsonResponse.SizeOfArray("Attributes.Tags.SS");
while (i < count_i) {
    jsonResponse.I = i;
    strVal = jsonResponse.StringOf("Attributes.Tags.SS[i]");
    i = i + 1;
}