(Lianja) DynamoDB - Query

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).

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

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loRest = createobject("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

loAuthAws = createobject("CkAuthAws")
loAuthAws.AccessKey = "AWS_ACCESS_KEY"
loAuthAws.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.)
loAuthAws.Region = "us-west-2"
loAuthAws.ServiceName = "dynamodb"
// SetAuthAws causes Chilkat to automatically add the following headers: Authorization, X-Amz-Date
loRest.SetAuthAws(loAuthAws)

// URL: https://dynamodb.us-west-2.amazonaws.com/
llBTls = .T.
lnPort = 443
llBAutoReconnect = .T.
llSuccess = loRest.Connect("dynamodb.us-west-2.amazonaws.com",lnPort,llBTls,llBAutoReconnect)
if (llSuccess <> .T.) then
    ? "ConnectFailReason: " + str(loRest.ConnectFailReason)
    ? loRest.LastErrorText
    release loRest
    release loAuthAws
    return
endif

// 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"
// }

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

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

loSbRequestBody = createobject("CkStringBuilder")
loJson.EmitSb(loSbRequestBody)
loSbResponseBody = createobject("CkStringBuilder")
llSuccess = loRest.FullRequestSb("POST","/",loSbRequestBody,loSbResponseBody)
if (llSuccess <> .T.) then
    ? loRest.LastErrorText
    release loRest
    release loAuthAws
    release loJson
    release loSbRequestBody
    release loSbResponseBody
    return
endif

lnRespStatusCode = loRest.ResponseStatusCode
? "response status code = " + str(lnRespStatusCode)
if (lnRespStatusCode >= 400) then
    ? "Response Status Code = " + str(lnRespStatusCode)
    ? "Response Header:"
    ? loRest.ResponseHeader
    ? "Response Body:"
    ? loSbResponseBody.GetAsString()
    release loRest
    release loAuthAws
    release loJson
    release loSbRequestBody
    release loSbResponseBody
    return
endif

loJsonResponse = createobject("CkJsonObject")
loJsonResponse.LoadSb(loSbResponseBody)

loJsonResponse.EmitCompact = .F.
? loJsonResponse.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

lnConsumedCapacityCapacityUnits = loJsonResponse.IntOf("ConsumedCapacity.CapacityUnits")
lcConsumedCapacityTableName = loJsonResponse.StringOf("ConsumedCapacity.TableName")
lnCount = loJsonResponse.IntOf("Count")
lnScannedCount = loJsonResponse.IntOf("ScannedCount")
i = 0
lnCount_i = loJsonResponse.SizeOfArray("Items")
do while i < lnCount_i
    loJsonResponse.I = i
    lcReplyDateTimeS = loJsonResponse.StringOf("Items[i].ReplyDateTime.S")
    lcPostedByS = loJsonResponse.StringOf("Items[i].PostedBy.S")
    lcIdS = loJsonResponse.StringOf("Items[i].Id.S")
    i = i + 1
enddo


release loRest
release loAuthAws
release loJson
release loSbRequestBody
release loSbResponseBody
release loJsonResponse