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). C++

#include <CkRest.h>
#include <CkAuthAws.h>
#include <CkJsonObject.h>
#include <CkStringBuilder.h>

void ChilkatSample(void)
    {
    bool success = false;

    CkRest 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

    CkAuthAws authAws;
    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/
    bool bTls = true;
    int port = 443;
    bool bAutoReconnect = true;
    success = rest.Connect("dynamodb.us-west-2.amazonaws.com",port,bTls,bAutoReconnect);
    if (success != true) {
        std::cout << "ConnectFailReason: " << rest.get_ConnectFailReason() << "\r\n";
        std::cout << rest.lastErrorText() << "\r\n";
        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;
    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;
    json.EmitSb(sbRequestBody);
    CkStringBuilder sbResponseBody;
    success = rest.FullRequestSb("POST","/",sbRequestBody,sbResponseBody);
    if (success != true) {
        std::cout << rest.lastErrorText() << "\r\n";
        return;
    }

    int respStatusCode = rest.get_ResponseStatusCode();
    std::cout << "response status code = " << respStatusCode << "\r\n";
    if (respStatusCode >= 400) {
        std::cout << "Response Status Code = " << respStatusCode << "\r\n";
        std::cout << "Response Header:" << "\r\n";
        std::cout << rest.responseHeader() << "\r\n";
        std::cout << "Response Body:" << "\r\n";
        std::cout << sbResponseBody.getAsString() << "\r\n";
        return;
    }

    CkJsonObject jsonResponse;
    jsonResponse.LoadSb(sbResponseBody);

    jsonResponse.put_EmitCompact(false);
    std::cout << jsonResponse.emit() << "\r\n";

    // 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 char *strVal = 0;

    const char *AttributesLastPostedByS = jsonResponse.stringOf("Attributes.LastPostedBy.S");
    const char *AttributesForumNameS = jsonResponse.stringOf("Attributes.ForumName.S");
    const char *AttributesLastPostDateTimeS = jsonResponse.stringOf("Attributes.LastPostDateTime.S");
    const char *AttributesSubjectS = jsonResponse.stringOf("Attributes.Subject.S");
    const char *AttributesViewsN = jsonResponse.stringOf("Attributes.Views.N");
    const char *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;
    }
    }