JavaScript

DynamoDB - Query

See more Amazon DynamoDB Examples

The Query operation finds items based on primary key values. You can query any table or secondary index that has a composite primary key (a partition key and a sort key). JavaScript

var success = false;

var rest = new CkRest();

// 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.Query" \
//   -d '{
//     "TableName": "Reply",
//     "IndexName": "PostedBy-Index",
//     "Limit": 3,
//     "ConsistentRead": true,
//     "ProjectionExpression": "Id, PostedBy, ReplyDateTime",
//     "KeyConditionExpression": "Id = :v1 AND PostedBy BETWEEN :v2a AND :v2b",
//     "ExpressionAttributeValues": {
//         ":v1": {"S": "Amazon DynamoDB#DynamoDB Thread 1"},
//         ":v2a": {"S": "User A"},
//         ":v2b": {"S": "User C"}
//     },
//     "ReturnConsumedCapacity": "TOTAL"
// }'

// Use the following online tool to generate REST code from a CURL command
// Convert a cURL Command to REST Source Code

var authAws = new CkAuthAws();
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/
var bTls = true;
var port = 443;
var bAutoReconnect = true;
success = rest.Connect("dynamodb.us-west-2.amazonaws.com",port,bTls,bAutoReconnect);
if (success !== true) {
    console.log("ConnectFailReason: " + rest.ConnectFailReason);
    console.log(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": "Reply",
//   "IndexName": "PostedBy-Index",
//   "Limit": 3,
//   "ConsistentRead": true,
//   "ProjectionExpression": "Id, PostedBy, ReplyDateTime",
//   "KeyConditionExpression": "Id = :v1 AND PostedBy BETWEEN :v2a AND :v2b",
//   "ExpressionAttributeValues": {
//     ":v1": {
//       "S": "Amazon DynamoDB#DynamoDB Thread 1"
//     },
//     ":v2a": {
//       "S": "User A"
//     },
//     ":v2b": {
//       "S": "User C"
//     }
//   },
//   "ReturnConsumedCapacity": "TOTAL"
// }

var json = new CkJsonObject();
json.UpdateString("TableName","Reply");
json.UpdateString("IndexName","PostedBy-Index");
json.UpdateInt("Limit",3);
json.UpdateBool("ConsistentRead",true);
json.UpdateString("ProjectionExpression","Id, PostedBy, ReplyDateTime");
json.UpdateString("KeyConditionExpression","Id = :v1 AND PostedBy BETWEEN :v2a AND :v2b");
json.UpdateString("ExpressionAttributeValues.:v1.S","Amazon DynamoDB#DynamoDB Thread 1");
json.UpdateString("ExpressionAttributeValues.:v2a.S","User A");
json.UpdateString("ExpressionAttributeValues.:v2b.S","User C");
json.UpdateString("ReturnConsumedCapacity","TOTAL");

rest.AddHeader("Content-Type","application/x-amz-json-1.0");
rest.AddHeader("X-Amz-Target","DynamoDB_20120810.Query");
rest.AddHeader("Accept-Encoding","identity");

var sbRequestBody = new CkStringBuilder();
json.EmitSb(sbRequestBody);
var sbResponseBody = new CkStringBuilder();
success = rest.FullRequestSb("POST","/",sbRequestBody,sbResponseBody);
if (success !== true) {
    console.log(rest.LastErrorText);
    return;
}

var respStatusCode = rest.ResponseStatusCode;
console.log("response status code = " + respStatusCode);
if (respStatusCode >= 400) {
    console.log("Response Status Code = " + respStatusCode);
    console.log("Response Header:");
    console.log(rest.ResponseHeader);
    console.log("Response Body:");
    console.log(sbResponseBody.GetAsString());
    return;
}

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

jsonResponse.EmitCompact = false;
console.log(jsonResponse.Emit());

// Sample JSON response:
// (Sample code for parsing the JSON response is shown below)

// {
//   "ConsumedCapacity": {
//     "CapacityUnits": 1,
//     "TableName": "Reply"
//   },
//   "Count": 2,
//   "Items": [
//     {
//       "ReplyDateTime": {
//         "S": "2015-02-18T20:27:36.165Z"
//       },
//       "PostedBy": {
//         "S": "User A"
//       },
//       "Id": {
//         "S": "Amazon DynamoDB#DynamoDB Thread 1"
//       }
//     },
//     {
//       "ReplyDateTime": {
//         "S": "2015-02-25T20:27:36.165Z"
//       },
//       "PostedBy": {
//         "S": "User B"
//       },
//       "Id": {
//         "S": "Amazon DynamoDB#DynamoDB Thread 1"
//       }
//     }
//   ],
//   "ScannedCount": 2
// }

// Sample code for parsing the JSON response...
// Use the following online tool to generate parsing code from sample JSON:
// Generate Parsing Code from JSON

var ReplyDateTimeS;
var PostedByS;
var IdS;

var ConsumedCapacityCapacityUnits = jsonResponse.IntOf("ConsumedCapacity.CapacityUnits");
var ConsumedCapacityTableName = jsonResponse.StringOf("ConsumedCapacity.TableName");
var Count = jsonResponse.IntOf("Count");
var ScannedCount = jsonResponse.IntOf("ScannedCount");
var i = 0;
var count_i = jsonResponse.SizeOfArray("Items");
while (i < count_i) {
    jsonResponse.I = i;
    ReplyDateTimeS = jsonResponse.StringOf("Items[i].ReplyDateTime.S");
    PostedByS = jsonResponse.StringOf("Items[i].PostedBy.S");
    IdS = jsonResponse.StringOf("Items[i].Id.S");
    i = i+1;
}