Java

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). Chilkat2 Java

import com.chilkatsoft.chilkat2.AuthAws;
import com.chilkatsoft.chilkat2.ChilkatException;
import com.chilkatsoft.chilkat2.JsonObject;
import com.chilkatsoft.chilkat2.Rest;
import com.chilkatsoft.chilkat2.StringBuilder;

public class ChilkatExample {

    public static void main(String[] args) {
        Rest rest = new 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

        AuthAws authAws = new AuthAws();
        authAws.setAccessKey("AWS_ACCESS_KEY");
        authAws.setSecretKey("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.setRegion("us-west-2");
        authAws.setServiceName("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;
        try {
            rest.connect("dynamodb.us-west-2.amazonaws.com", port, bTls, bAutoReconnect);
        } catch (ChilkatException e) {
            System.out.println("ConnectFailReason: " + rest.getConnectFailReason());
            System.out.println(e.getLastErrorText());
            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"
        // }

        JsonObject json = new 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");

        StringBuilder sbRequestBody = new StringBuilder();
        json.emitSb(sbRequestBody);
        StringBuilder sbResponseBody = new StringBuilder();
        try {
            rest.fullRequestSb("POST", "/", sbRequestBody, sbResponseBody);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        int respStatusCode = rest.getResponseStatusCode();
        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.getResponseHeader());
            System.out.println("Response Body:");
            System.out.println(sbResponseBody.getAsString());
            return;
        }

        JsonObject jsonResponse = new JsonObject();
        jsonResponse.loadSb(sbResponseBody);

        jsonResponse.setEmitCompact(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.setI(i);
            strVal = jsonResponse.stringOf("Attributes.Tags.SS[i]");
            i = i + 1;
        }
    }
}