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Visual FoxPro

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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LOCAL lnSuccess
LOCAL loRest
LOCAL loAuthAws
LOCAL lnBTls
LOCAL lnPort
LOCAL lnBAutoReconnect
LOCAL loJson
LOCAL loSbRequestBody
LOCAL loSbResponseBody
LOCAL lnRespStatusCode
LOCAL loJsonResponse
LOCAL lcStrVal
LOCAL lcAttributesLastPostedByS
LOCAL lcAttributesForumNameS
LOCAL lcAttributesLastPostDateTimeS
LOCAL lcAttributesSubjectS
LOCAL lcAttributesViewsN
LOCAL lcAttributesMessageS
LOCAL i
LOCAL lnCount_i

lnSuccess = 0

loRest = CreateObject('Chilkat.Rest')

* 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('Chilkat.AuthAws')
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/
lnBTls = 1
lnPort = 443
lnBAutoReconnect = 1
lnSuccess = loRest.Connect("dynamodb.us-west-2.amazonaws.com",lnPort,lnBTls,lnBAutoReconnect)
IF (lnSuccess <> 1) THEN
    ? "ConnectFailReason: " + STR(loRest.ConnectFailReason)
    ? loRest.LastErrorText
    RELEASE loRest
    RELEASE loAuthAws
    CANCEL
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('Chilkat.JsonObject')
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('Chilkat.StringBuilder')
loJson.EmitSb(loSbRequestBody)
loSbResponseBody = CreateObject('Chilkat.StringBuilder')
lnSuccess = loRest.FullRequestSb("POST","/",loSbRequestBody,loSbResponseBody)
IF (lnSuccess <> 1) THEN
    ? loRest.LastErrorText
    RELEASE loRest
    RELEASE loAuthAws
    RELEASE loJson
    RELEASE loSbRequestBody
    RELEASE loSbResponseBody
    CANCEL
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
    CANCEL
ENDIF

loJsonResponse = CreateObject('Chilkat.JsonObject')
loJsonResponse.LoadSb(loSbResponseBody)

loJsonResponse.EmitCompact = 0
? 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