(Objective-C) DynamoDB - DeleteItem

Deletes a single item in a table by primary key. You can perform a conditional delete operation that deletes the item if it exists, or if it has an expected attribute value.

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

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

CkoRest *rest = [[CkoRest alloc] init];
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.DeleteItem" \
//   -d '{
//     "TableName": "Thread",
//     "Key": {
//         "ForumName": {
//             "S": "Amazon DynamoDB"
//         },
//         "Subject": {
//             "S": "How do I update multiple items?"
//         }
//     },
//     "ConditionExpression": "attribute_not_exists(Replies)",
//     "ReturnValues": "ALL_OLD"
// }'

// 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": "How do I update multiple items?"
//     }
//   },
//   "ConditionExpression": "attribute_not_exists(Replies)",
//   "ReturnValues": "ALL_OLD"
// }

CkoJsonObject *json = [[CkoJsonObject alloc] init];
[json UpdateString: @"TableName" value: @"Thread"];
[json UpdateString: @"Key.ForumName.S" value: @"Amazon DynamoDB"];
[json UpdateString: @"Key.Subject.S" value: @"How do I update multiple items?"];
[json UpdateString: @"ConditionExpression" value: @"attribute_not_exists(Replies)"];
[json UpdateString: @"ReturnValues" value: @"ALL_OLD"];

[rest AddHeader: @"Content-Type" value: @"application/x-amz-json-1.0"];
[rest AddHeader: @"X-Amz-Target" value: @"DynamoDB_20120810.DeleteItem"];
[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": "fred@example.com"
//     },
//     "ForumName": {
//       "S": "Amazon DynamoDB"
//     },
//     "LastPostDateTime": {
//       "S": "201303201023"
//     },
//     "Tags": {
//       "SS": [
//         "Update",
//         "Multiple Items",
//         "HelpMe"
//       ]
//     },
//     "Subject": {
//       "S": "How do I update multiple items?"
//     },
//     "Message": {
//       "S": "I want to update multiple items in a single call. What's the best way to do that?"
//     }
//   }
// }

// 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 *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;
}