(PureBasic) DynamoDB - GetItem

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.

For more information, see https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_GetItem.html

Chilkat PureBasic Module Download Chilkat PureBasic Module

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

Procedure ChilkatExample()

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

    success.i

    ; 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

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

    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,"ProjectionExpression","LastPostDateTime, Message, Tags")
    CkJsonObject::ckUpdateBool(json,"ConsistentRead",1)
    CkJsonObject::ckUpdateString(json,"ReturnConsumedCapacity","TOTAL")

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

    ; {
    ;   "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

    strVal.s

    ConsumedCapacityCapacityUnits.i = CkJsonObject::ckIntOf(jsonResponse,"ConsumedCapacity.CapacityUnits")
    ConsumedCapacityTableName.s = CkJsonObject::ckStringOf(jsonResponse,"ConsumedCapacity.TableName")
    ItemLastPostDateTimeS.s = CkJsonObject::ckStringOf(jsonResponse,"Item.LastPostDateTime.S")
    ItemMessageS.s = CkJsonObject::ckStringOf(jsonResponse,"Item.Message.S")
    i.i = 0
    count_i.i = CkJsonObject::ckSizeOfArray(jsonResponse,"Item.Tags.SS")
    While i < count_i
        CkJsonObject::setCkI(jsonResponse, i)
        strVal = CkJsonObject::ckStringOf(jsonResponse,"Item.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