Tcl

DynamoDB - UpdateItem

See more Amazon DynamoDB Examples

Edits an existing item's attributes, or adds a new item to the table if it does not already exist. You can put, delete, or add attribute values. You can also perform a conditional update on an existing item (insert a new attribute name-value pair if it doesn't exist, or replace an existing name-value pair if it has certain expected attribute values). 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.UpdateItem" \
#   -d '{
#     "TableName": "Thread",
#     "Key": {
#         "ForumName": {
#             "S": "Amazon DynamoDB"
#         },
#         "Subject": {
#             "S": "Maximum number of items?"
#         }
#     },
#     "UpdateExpression": "set LastPostedBy = :val1",
#     "ConditionExpression": "LastPostedBy = :val2",
#     "ExpressionAttributeValues": {
#         ":val1": {"S": "alice@example.com"},
#         ":val2": {"S": "fred@example.com"}
#     },
#     "ReturnValues": "ALL_NEW"
# }'

# 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": "Maximum number of items?"
#     }
#   },
#   "UpdateExpression": "set LastPostedBy = :val1",
#   "ConditionExpression": "LastPostedBy = :val2",
#   "ExpressionAttributeValues": {
#     ":val1": {
#       "S": "alice@example.com"
#     },
#     ":val2": {
#       "S": "fred@example.com"
#     }
#   },
#   "ReturnValues": "ALL_NEW"
# }

set json [new_CkJsonObject]

CkJsonObject_UpdateString $json "TableName" "Thread"
CkJsonObject_UpdateString $json "Key.ForumName.S" "Amazon DynamoDB"
CkJsonObject_UpdateString $json "Key.Subject.S" "Maximum number of items?"
CkJsonObject_UpdateString $json "UpdateExpression" "set LastPostedBy = :val1"
CkJsonObject_UpdateString $json "ConditionExpression" "LastPostedBy = :val2"
CkJsonObject_UpdateString $json "ExpressionAttributeValues.:val1.S" "alice@example.com"
CkJsonObject_UpdateString $json "ExpressionAttributeValues.:val2.S" "fred@example.com"
CkJsonObject_UpdateString $json "ReturnValues" "ALL_NEW"

CkRest_AddHeader $rest "Content-Type" "application/x-amz-json-1.0"
CkRest_AddHeader $rest "X-Amz-Target" "DynamoDB_20120810.UpdateItem"
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)

# {
#   "Attributes": {
#     "LastPostedBy": {
#       "S": "alice@example.com"
#     },
#     "ForumName": {
#       "S": "Amazon DynamoDB"
#     },
#     "LastPostDateTime": {
#       "S": "20130320010350"
#     },
#     "Tags": {
#       "SS": [
#         "Update",
#         "Multiple Items",
#         "HelpMe"
#       ]
#     },
#     "Subject": {
#       "S": "Maximum number of items?"
#     },
#     "Views": {
#       "N": "5"
#     },
#     "Message": {
#       "S": "I want to put 10 million data items to an Amazon DynamoDB table.  Is there an upper limit?"
#     }
#   }
# }

# 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 AttributesLastPostedByS [CkJsonObject_stringOf $jsonResponse "Attributes.LastPostedBy.S"]
set AttributesForumNameS [CkJsonObject_stringOf $jsonResponse "Attributes.ForumName.S"]
set AttributesLastPostDateTimeS [CkJsonObject_stringOf $jsonResponse "Attributes.LastPostDateTime.S"]
set AttributesSubjectS [CkJsonObject_stringOf $jsonResponse "Attributes.Subject.S"]
set AttributesViewsN [CkJsonObject_stringOf $jsonResponse "Attributes.Views.N"]
set AttributesMessageS [CkJsonObject_stringOf $jsonResponse "Attributes.Message.S"]
set i 0
set count_i [CkJsonObject_SizeOfArray $jsonResponse "Attributes.Tags.SS"]
while {$i < $count_i} {
    CkJsonObject_put_I $jsonResponse $i
    set strVal [CkJsonObject_stringOf $jsonResponse "Attributes.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