PureBasic

DynamoDB - DeleteItem

See more Amazon DynamoDB Examples

Deletes a single item in a table by primary key. You can perform a conditional delete operation that deletes the item if it exists, or if it has an expected attribute value. PureBasic

IncludeFile "CkStringBuilder.pb"
IncludeFile "CkAuthAws.pb"
IncludeFile "CkJsonObject.pb"
IncludeFile "CkRest.pb"

Procedure ChilkatExample()

    success.i = 0

    rest.i = CkRest::ckCreate()
    If rest.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; 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.DeleteItem" \
    ;   -d '{
    ;     "TableName": "Thread",
    ;     "Key": {
    ;         "ForumName": {
    ;             "S": "Amazon DynamoDB"
    ;         },
    ;         "Subject": {
    ;             "S": "How do I update multiple items?"
    ;         }
    ;     },
    ;     "ConditionExpression": "attribute_not_exists(Replies)",
    ;     "ReturnValues": "ALL_OLD"
    ; }'

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

    authAws.i = CkAuthAws::ckCreate()
    If authAws.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkAuthAws::setCkAccessKey(authAws, "AWS_ACCESS_KEY")
    CkAuthAws::setCkSecretKey(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::setCkRegion(authAws, "us-west-2")
    CkAuthAws::setCkServiceName(authAws, "dynamodb")
    ; SetAuthAws causes Chilkat to automatically add the following headers: Authorization, X-Amz-Date
    CkRest::ckSetAuthAws(rest,authAws)

    ; URL: https://dynamodb.us-west-2.amazonaws.com/
    bTls.i = 1
    port.i = 443
    bAutoReconnect.i = 1
    success = CkRest::ckConnect(rest,"dynamodb.us-west-2.amazonaws.com",port,bTls,bAutoReconnect)
    If success <> 1
        Debug "ConnectFailReason: " + Str(CkRest::ckConnectFailReason(rest))
        Debug CkRest::ckLastErrorText(rest)
        CkRest::ckDispose(rest)
        CkAuthAws::ckDispose(authAws)
        ProcedureReturn
    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": "How do I update multiple items?"
    ;     }
    ;   },
    ;   "ConditionExpression": "attribute_not_exists(Replies)",
    ;   "ReturnValues": "ALL_OLD"
    ; }

    json.i = CkJsonObject::ckCreate()
    If json.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkJsonObject::ckUpdateString(json,"TableName","Thread")
    CkJsonObject::ckUpdateString(json,"Key.ForumName.S","Amazon DynamoDB")
    CkJsonObject::ckUpdateString(json,"Key.Subject.S","How do I update multiple items?")
    CkJsonObject::ckUpdateString(json,"ConditionExpression","attribute_not_exists(Replies)")
    CkJsonObject::ckUpdateString(json,"ReturnValues","ALL_OLD")

    CkRest::ckAddHeader(rest,"Content-Type","application/x-amz-json-1.0")
    CkRest::ckAddHeader(rest,"X-Amz-Target","DynamoDB_20120810.DeleteItem")
    CkRest::ckAddHeader(rest,"Accept-Encoding","identity")

    sbRequestBody.i = CkStringBuilder::ckCreate()
    If sbRequestBody.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkJsonObject::ckEmitSb(json,sbRequestBody)
    sbResponseBody.i = CkStringBuilder::ckCreate()
    If sbResponseBody.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkRest::ckFullRequestSb(rest,"POST","/",sbRequestBody,sbResponseBody)
    If success <> 1
        Debug CkRest::ckLastErrorText(rest)
        CkRest::ckDispose(rest)
        CkAuthAws::ckDispose(authAws)
        CkJsonObject::ckDispose(json)
        CkStringBuilder::ckDispose(sbRequestBody)
        CkStringBuilder::ckDispose(sbResponseBody)
        ProcedureReturn
    EndIf

    respStatusCode.i = CkRest::ckResponseStatusCode(rest)
    Debug "response status code = " + Str(respStatusCode)
    If respStatusCode >= 400
        Debug "Response Status Code = " + Str(respStatusCode)
        Debug "Response Header:"
        Debug CkRest::ckResponseHeader(rest)
        Debug "Response Body:"
        Debug CkStringBuilder::ckGetAsString(sbResponseBody)
        CkRest::ckDispose(rest)
        CkAuthAws::ckDispose(authAws)
        CkJsonObject::ckDispose(json)
        CkStringBuilder::ckDispose(sbRequestBody)
        CkStringBuilder::ckDispose(sbResponseBody)
        ProcedureReturn
    EndIf

    jsonResponse.i = CkJsonObject::ckCreate()
    If jsonResponse.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkJsonObject::ckLoadSb(jsonResponse,sbResponseBody)

    CkJsonObject::setCkEmitCompact(jsonResponse, 0)
    Debug CkJsonObject::ckEmit(jsonResponse)

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

    ; {
    ;   "Attributes": {
    ;     "LastPostedBy": {
    ;       "S": "fred@example.com"
    ;     },
    ;     "ForumName": {
    ;       "S": "Amazon DynamoDB"
    ;     },
    ;     "LastPostDateTime": {
    ;       "S": "201303201023"
    ;     },
    ;     "Tags": {
    ;       "SS": [
    ;         "Update",
    ;         "Multiple Items",
    ;         "HelpMe"
    ;       ]
    ;     },
    ;     "Subject": {
    ;       "S": "How do I update multiple items?"
    ;     },
    ;     "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

    strVal.s

    AttributesLastPostedByS.s = CkJsonObject::ckStringOf(jsonResponse,"Attributes.LastPostedBy.S")
    AttributesForumNameS.s = CkJsonObject::ckStringOf(jsonResponse,"Attributes.ForumName.S")
    AttributesLastPostDateTimeS.s = CkJsonObject::ckStringOf(jsonResponse,"Attributes.LastPostDateTime.S")
    AttributesSubjectS.s = CkJsonObject::ckStringOf(jsonResponse,"Attributes.Subject.S")
    AttributesMessageS.s = CkJsonObject::ckStringOf(jsonResponse,"Attributes.Message.S")
    i.i = 0
    count_i.i = CkJsonObject::ckSizeOfArray(jsonResponse,"Attributes.Tags.SS")
    While i < count_i
        CkJsonObject::setCkI(jsonResponse, i)
        strVal = CkJsonObject::ckStringOf(jsonResponse,"Attributes.Tags.SS[i]")
        i = i + 1
    Wend


    CkRest::ckDispose(rest)
    CkAuthAws::ckDispose(authAws)
    CkJsonObject::ckDispose(json)
    CkStringBuilder::ckDispose(sbRequestBody)
    CkStringBuilder::ckDispose(sbResponseBody)
    CkJsonObject::ckDispose(jsonResponse)


    ProcedureReturn
EndProcedure