(PureBasic) DynamoDB - Query

The Query operation finds items based on primary key values. You can query any table or secondary index that has a composite primary key (a partition key and a sort key).

For more information, see https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_Query.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.Query" \
    ;   -d '{
    ;     "TableName": "Reply",
    ;     "IndexName": "PostedBy-Index",
    ;     "Limit": 3,
    ;     "ConsistentRead": true,
    ;     "ProjectionExpression": "Id, PostedBy, ReplyDateTime",
    ;     "KeyConditionExpression": "Id = :v1 AND PostedBy BETWEEN :v2a AND :v2b",
    ;     "ExpressionAttributeValues": {
    ;         ":v1": {"S": "Amazon DynamoDB#DynamoDB Thread 1"},
    ;         ":v2a": {"S": "User A"},
    ;         ":v2b": {"S": "User C"}
    ;     },
    ;     "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": "Reply",
    ;   "IndexName": "PostedBy-Index",
    ;   "Limit": 3,
    ;   "ConsistentRead": true,
    ;   "ProjectionExpression": "Id, PostedBy, ReplyDateTime",
    ;   "KeyConditionExpression": "Id = :v1 AND PostedBy BETWEEN :v2a AND :v2b",
    ;   "ExpressionAttributeValues": {
    ;     ":v1": {
    ;       "S": "Amazon DynamoDB#DynamoDB Thread 1"
    ;     },
    ;     ":v2a": {
    ;       "S": "User A"
    ;     },
    ;     ":v2b": {
    ;       "S": "User C"
    ;     }
    ;   },
    ;   "ReturnConsumedCapacity": "TOTAL"
    ; }

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

    CkJsonObject::ckUpdateString(json,"TableName","Reply")
    CkJsonObject::ckUpdateString(json,"IndexName","PostedBy-Index")
    CkJsonObject::ckUpdateInt(json,"Limit",3)
    CkJsonObject::ckUpdateBool(json,"ConsistentRead",1)
    CkJsonObject::ckUpdateString(json,"ProjectionExpression","Id, PostedBy, ReplyDateTime")
    CkJsonObject::ckUpdateString(json,"KeyConditionExpression","Id = :v1 AND PostedBy BETWEEN :v2a AND :v2b")
    CkJsonObject::ckUpdateString(json,"ExpressionAttributeValues.:v1.S","Amazon DynamoDB#DynamoDB Thread 1")
    CkJsonObject::ckUpdateString(json,"ExpressionAttributeValues.:v2a.S","User A")
    CkJsonObject::ckUpdateString(json,"ExpressionAttributeValues.:v2b.S","User C")
    CkJsonObject::ckUpdateString(json,"ReturnConsumedCapacity","TOTAL")

    CkRest::ckAddHeader(rest,"Content-Type","application/x-amz-json-1.0")
    CkRest::ckAddHeader(rest,"X-Amz-Target","DynamoDB_20120810.Query")
    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": "Reply"
    ;   },
    ;   "Count": 2,
    ;   "Items": [
    ;     {
    ;       "ReplyDateTime": {
    ;         "S": "2015-02-18T20:27:36.165Z"
    ;       },
    ;       "PostedBy": {
    ;         "S": "User A"
    ;       },
    ;       "Id": {
    ;         "S": "Amazon DynamoDB#DynamoDB Thread 1"
    ;       }
    ;     },
    ;     {
    ;       "ReplyDateTime": {
    ;         "S": "2015-02-25T20:27:36.165Z"
    ;       },
    ;       "PostedBy": {
    ;         "S": "User B"
    ;       },
    ;       "Id": {
    ;         "S": "Amazon DynamoDB#DynamoDB Thread 1"
    ;       }
    ;     }
    ;   ],
    ;   "ScannedCount": 2
    ; }

    ; Sample code for parsing the JSON response...
    ; Use the following online tool to generate parsing code from sample JSON:
    ; Generate Parsing Code from JSON

    ReplyDateTimeS.s
    PostedByS.s
    IdS.s

    ConsumedCapacityCapacityUnits.i = CkJsonObject::ckIntOf(jsonResponse,"ConsumedCapacity.CapacityUnits")
    ConsumedCapacityTableName.s = CkJsonObject::ckStringOf(jsonResponse,"ConsumedCapacity.TableName")
    Count.i = CkJsonObject::ckIntOf(jsonResponse,"Count")
    ScannedCount.i = CkJsonObject::ckIntOf(jsonResponse,"ScannedCount")
    i.i = 0
    count_i.i = CkJsonObject::ckSizeOfArray(jsonResponse,"Items")
    While i < count_i
        CkJsonObject::setCkI(jsonResponse, i)
        ReplyDateTimeS = CkJsonObject::ckStringOf(jsonResponse,"Items[i].ReplyDateTime.S")
        PostedByS = CkJsonObject::ckStringOf(jsonResponse,"Items[i].PostedBy.S")
        IdS = CkJsonObject::ckStringOf(jsonResponse,"Items[i].Id.S")
        i = i + 1
    Wend


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


    ProcedureReturn
EndProcedure