(Java) 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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import com.chilkatsoft.*;

public class ChilkatExample {

  static {
    try {
        System.loadLibrary("chilkat");
    } catch (UnsatisfiedLinkError e) {
      System.err.println("Native code library failed to load.\n" + e);
      System.exit(1);
    }
  }

  public static void main(String argv[])
  {
    CkRest rest = new CkRest();
    boolean 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

    CkAuthAws authAws = new CkAuthAws();
    authAws.put_AccessKey("AWS_ACCESS_KEY");
    authAws.put_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.put_Region("us-west-2");
    authAws.put_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/
    boolean bTls = true;
    int port = 443;
    boolean bAutoReconnect = true;
    success = rest.Connect("dynamodb.us-west-2.amazonaws.com",port,bTls,bAutoReconnect);
    if (success != true) {
        System.out.println("ConnectFailReason: " + rest.get_ConnectFailReason());
        System.out.println(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"
    // }

    CkJsonObject json = new CkJsonObject();
    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");

    CkStringBuilder sbRequestBody = new CkStringBuilder();
    json.EmitSb(sbRequestBody);
    CkStringBuilder sbResponseBody = new CkStringBuilder();
    success = rest.FullRequestSb("POST","/",sbRequestBody,sbResponseBody);
    if (success != true) {
        System.out.println(rest.lastErrorText());
        return;
        }

    int respStatusCode = rest.get_ResponseStatusCode();
    System.out.println("response status code = " + respStatusCode);
    if (respStatusCode >= 400) {
        System.out.println("Response Status Code = " + respStatusCode);
        System.out.println("Response Header:");
        System.out.println(rest.responseHeader());
        System.out.println("Response Body:");
        System.out.println(sbResponseBody.getAsString());
        return;
        }

    CkJsonObject jsonResponse = new CkJsonObject();
    jsonResponse.LoadSb(sbResponseBody);

    jsonResponse.put_EmitCompact(false);
    System.out.println(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.put_I(i);
        strVal = jsonResponse.stringOf("Attributes.Tags.SS[i]");
        i = i+1;
        }
  }
}