(Ruby) 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

Chilkat Ruby Downloads install from rubygems.org gem install chilkat or download... Ruby Library for Windows, MacOS, Linux, Alpine Linux

require 'chilkat'

rest = Chilkat::CkRest.new()

# 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

authAws = Chilkat::CkAuthAws.new()
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/
bTls = true
port = 443
bAutoReconnect = true
success = rest.Connect("dynamodb.us-west-2.amazonaws.com",port,bTls,bAutoReconnect)
if (success != true)
    print "ConnectFailReason: " + rest.get_ConnectFailReason().to_s() + "\n";
    print rest.lastErrorText() + "\n";
    exit
end

# 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"
# }

json = Chilkat::CkJsonObject.new()
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")

sbRequestBody = Chilkat::CkStringBuilder.new()
json.EmitSb(sbRequestBody)
sbResponseBody = Chilkat::CkStringBuilder.new()
success = rest.FullRequestSb("POST","/",sbRequestBody,sbResponseBody)
if (success != true)
    print rest.lastErrorText() + "\n";
    exit
end

respStatusCode = rest.get_ResponseStatusCode()
print "response status code = " + respStatusCode.to_s() + "\n";
if (respStatusCode >= 400)
    print "Response Status Code = " + respStatusCode.to_s() + "\n";
    print "Response Header:" + "\n";
    print rest.responseHeader() + "\n";
    print "Response Body:" + "\n";
    print sbResponseBody.getAsString() + "\n";
    exit
end

jsonResponse = Chilkat::CkJsonObject.new()
jsonResponse.LoadSb(sbResponseBody)

jsonResponse.put_EmitCompact(false)
print jsonResponse.emit() + "\n";

# 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

ConsumedCapacityCapacityUnits = jsonResponse.IntOf("ConsumedCapacity.CapacityUnits")
ConsumedCapacityTableName = jsonResponse.stringOf("ConsumedCapacity.TableName")
Count = jsonResponse.IntOf("Count")
ScannedCount = jsonResponse.IntOf("ScannedCount")
i = 0
count_i = jsonResponse.SizeOfArray("Items")
while i < count_i
    jsonResponse.put_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
end