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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).

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llSuccess = .F.

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.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

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": "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"
// }

loJson = createobject("CkJsonObject")
loJson.UpdateString("TableName","Thread")
loJson.UpdateString("Key.ForumName.S","Amazon DynamoDB")
loJson.UpdateString("Key.Subject.S","Maximum number of items?")
loJson.UpdateString("UpdateExpression","set LastPostedBy = :val1")
loJson.UpdateString("ConditionExpression","LastPostedBy = :val2")
loJson.UpdateString("ExpressionAttributeValues.:val1.S","alice@example.com")
loJson.UpdateString("ExpressionAttributeValues.:val2.S","fred@example.com")
loJson.UpdateString("ReturnValues","ALL_NEW")

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

// {
//   "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

lcAttributesLastPostedByS = loJsonResponse.StringOf("Attributes.LastPostedBy.S")
lcAttributesForumNameS = loJsonResponse.StringOf("Attributes.ForumName.S")
lcAttributesLastPostDateTimeS = loJsonResponse.StringOf("Attributes.LastPostDateTime.S")
lcAttributesSubjectS = loJsonResponse.StringOf("Attributes.Subject.S")
lcAttributesViewsN = loJsonResponse.StringOf("Attributes.Views.N")
lcAttributesMessageS = loJsonResponse.StringOf("Attributes.Message.S")
i = 0
lnCount_i = loJsonResponse.SizeOfArray("Attributes.Tags.SS")
do while i < lnCount_i
    loJsonResponse.I = i
    lcStrVal = loJsonResponse.StringOf("Attributes.Tags.SS[i]")
    i = i + 1
enddo


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