Tcl

DynamoDB - GetItem

See more Amazon DynamoDB Examples

The GetItem operation returns a set of attributes for the item with the given primary key. If there is no matching item, GetItem does not return any data and there will be no Item element in the response. Tcl

load ./chilkat.dll

set success 0

set 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.GetItem" \
#   -d '{
#     "TableName": "Thread",
#     "Key": {
#         "ForumName": {
#             "S": "Amazon DynamoDB"
#         },
#         "Subject": {
#             "S": "How do I update multiple items?"
#         }
#     },
#     "ProjectionExpression":"LastPostDateTime, Message, Tags",
#     "ConsistentRead": true,
#     "ReturnConsumedCapacity": "TOTAL"
# }'

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

set authAws [new_CkAuthAws]

CkAuthAws_put_AccessKey $authAws "AWS_ACCESS_KEY"
CkAuthAws_put_SecretKey $authAws "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.)
CkAuthAws_put_Region $authAws "us-west-2"
CkAuthAws_put_ServiceName $authAws "dynamodb"
# SetAuthAws causes Chilkat to automatically add the following headers: Authorization, X-Amz-Date
CkRest_SetAuthAws $rest $authAws

# URL: https://dynamodb.us-west-2.amazonaws.com/
set bTls 1
set port 443
set bAutoReconnect 1
set success [CkRest_Connect $rest "dynamodb.us-west-2.amazonaws.com" $port $bTls $bAutoReconnect]
if {$success != 1} then {
    puts "ConnectFailReason: [CkRest_get_ConnectFailReason $rest]"
    puts [CkRest_lastErrorText $rest]
    delete_CkRest $rest
    delete_CkAuthAws $authAws
    exit
}

# 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?"
#     }
#   },
#   "ProjectionExpression": "LastPostDateTime, Message, Tags",
#   "ConsistentRead": true,
#   "ReturnConsumedCapacity": "TOTAL"
# }

set json [new_CkJsonObject]

CkJsonObject_UpdateString $json "TableName" "Thread"
CkJsonObject_UpdateString $json "Key.ForumName.S" "Amazon DynamoDB"
CkJsonObject_UpdateString $json "Key.Subject.S" "How do I update multiple items?"
CkJsonObject_UpdateString $json "ProjectionExpression" "LastPostDateTime, Message, Tags"
CkJsonObject_UpdateBool $json "ConsistentRead" 1
CkJsonObject_UpdateString $json "ReturnConsumedCapacity" "TOTAL"

CkRest_AddHeader $rest "Content-Type" "application/x-amz-json-1.0"
CkRest_AddHeader $rest "X-Amz-Target" "DynamoDB_20120810.GetItem"
CkRest_AddHeader $rest "Accept-Encoding" "identity"

set sbRequestBody [new_CkStringBuilder]

CkJsonObject_EmitSb $json $sbRequestBody
set sbResponseBody [new_CkStringBuilder]

set success [CkRest_FullRequestSb $rest "POST" "/" $sbRequestBody $sbResponseBody]
if {$success != 1} then {
    puts [CkRest_lastErrorText $rest]
    delete_CkRest $rest
    delete_CkAuthAws $authAws
    delete_CkJsonObject $json
    delete_CkStringBuilder $sbRequestBody
    delete_CkStringBuilder $sbResponseBody
    exit
}

set respStatusCode [CkRest_get_ResponseStatusCode $rest]
puts "response status code = $respStatusCode"
if {$respStatusCode >= 400} then {
    puts "Response Status Code = $respStatusCode"
    puts "Response Header:"
    puts [CkRest_responseHeader $rest]
    puts "Response Body:"
    puts [CkStringBuilder_getAsString $sbResponseBody]
    delete_CkRest $rest
    delete_CkAuthAws $authAws
    delete_CkJsonObject $json
    delete_CkStringBuilder $sbRequestBody
    delete_CkStringBuilder $sbResponseBody
    exit
}

set jsonResponse [new_CkJsonObject]

CkJsonObject_LoadSb $jsonResponse $sbResponseBody

CkJsonObject_put_EmitCompact $jsonResponse 0
puts [CkJsonObject_emit $jsonResponse]

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

# {
#   "ConsumedCapacity": {
#     "CapacityUnits": 1,
#     "TableName": "Thread"
#   },
#   "Item": {
#     "Tags": {
#       "SS": [
#         "Update",
#         "Multiple Items",
#         "HelpMe"
#       ]
#     },
#     "LastPostDateTime": {
#       "S": "201303190436"
#     },
#     "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

set ConsumedCapacityCapacityUnits [CkJsonObject_IntOf $jsonResponse "ConsumedCapacity.CapacityUnits"]
set ConsumedCapacityTableName [CkJsonObject_stringOf $jsonResponse "ConsumedCapacity.TableName"]
set ItemLastPostDateTimeS [CkJsonObject_stringOf $jsonResponse "Item.LastPostDateTime.S"]
set ItemMessageS [CkJsonObject_stringOf $jsonResponse "Item.Message.S"]
set i 0
set count_i [CkJsonObject_SizeOfArray $jsonResponse "Item.Tags.SS"]
while {$i < $count_i} {
    CkJsonObject_put_I $jsonResponse $i
    set strVal [CkJsonObject_stringOf $jsonResponse "Item.Tags.SS[i]"]
    set i [expr $i + 1]
}

delete_CkRest $rest
delete_CkAuthAws $authAws
delete_CkJsonObject $json
delete_CkStringBuilder $sbRequestBody
delete_CkStringBuilder $sbResponseBody
delete_CkJsonObject $jsonResponse