Objective-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). Objective-C

#import <CkoRest.h>
#import <CkoAuthAws.h>
#import <CkoJsonObject.h>
#import <CkoStringBuilder.h>
#import <NSString.h>

BOOL success = NO;

CkoRest *rest = [[CkoRest alloc] init];

//  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

CkoAuthAws *authAws = [[CkoAuthAws alloc] init];
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 = YES;
int port = 443;
BOOL bAutoReconnect = YES;
success = [rest Connect: @"dynamodb.us-west-2.amazonaws.com" port: [NSNumber numberWithInt: port] tls: bTls autoReconnect: bAutoReconnect];
if (success != YES) {
    NSLog(@"%@%d",@"ConnectFailReason: ",[rest.ConnectFailReason intValue]);
    NSLog(@"%@",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"
//  }

CkoJsonObject *json = [[CkoJsonObject alloc] init];
[json UpdateString: @"TableName" value: @"Thread"];
[json UpdateString: @"Key.ForumName.S" value: @"Amazon DynamoDB"];
[json UpdateString: @"Key.Subject.S" value: @"Maximum number of items?"];
[json UpdateString: @"UpdateExpression" value: @"set LastPostedBy = :val1"];
[json UpdateString: @"ConditionExpression" value: @"LastPostedBy = :val2"];
[json UpdateString: @"ExpressionAttributeValues.:val1.S" value: @"alice@example.com"];
[json UpdateString: @"ExpressionAttributeValues.:val2.S" value: @"fred@example.com"];
[json UpdateString: @"ReturnValues" value: @"ALL_NEW"];

[rest AddHeader: @"Content-Type" value: @"application/x-amz-json-1.0"];
[rest AddHeader: @"X-Amz-Target" value: @"DynamoDB_20120810.UpdateItem"];
[rest AddHeader: @"Accept-Encoding" value: @"identity"];

CkoStringBuilder *sbRequestBody = [[CkoStringBuilder alloc] init];
[json EmitSb: sbRequestBody];
CkoStringBuilder *sbResponseBody = [[CkoStringBuilder alloc] init];
success = [rest FullRequestSb: @"POST" uriPath: @"/" requestBody: sbRequestBody responseBody: sbResponseBody];
if (success != YES) {
    NSLog(@"%@",rest.LastErrorText);
    return;
}

int respStatusCode = [rest.ResponseStatusCode intValue];
NSLog(@"%@%d",@"response status code = ",respStatusCode);
if (respStatusCode >= 400) {
    NSLog(@"%@%d",@"Response Status Code = ",respStatusCode);
    NSLog(@"%@",@"Response Header:");
    NSLog(@"%@",rest.ResponseHeader);
    NSLog(@"%@",@"Response Body:");
    NSLog(@"%@",[sbResponseBody GetAsString]);
    return;
}

CkoJsonObject *jsonResponse = [[CkoJsonObject alloc] init];
[jsonResponse LoadSb: sbResponseBody];

jsonResponse.EmitCompact = NO;
NSLog(@"%@",[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

NSString *strVal = 0;

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