(Go) 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 Go Downloads Go Package for Windows, MacOS, Linux, Alpine Linux, Solaris

    rest := chilkat.NewRest()
    var success bool

    // 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 := chilkat.NewAuthAws()
    authAws.SetAccessKey("AWS_ACCESS_KEY")
    authAws.SetSecretKey("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.)
    authAws.SetRegion("us-west-2")
    authAws.SetServiceName("dynamodb")
    // SetAuthAws causes Chilkat to automatically add the following headers: Authorization, X-Amz-Date
    rest.SetAuthAws(authAws)

    // URL: https://dynamodb.us-west-2.amazonaws.com/
    bTls := true
    port := 443
    bAutoReconnect := true
    success = rest.Connect("dynamodb.us-west-2.amazonaws.com",port,bTls,bAutoReconnect)
    if success != true {
        fmt.Println("ConnectFailReason: ", rest.ConnectFailReason())
        fmt.Println(rest.LastErrorText())
        rest.DisposeRest()
        authAws.DisposeAuthAws()
        return
    }

    // 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 := chilkat.NewJsonObject()
    json.UpdateString("TableName","Reply")
    json.UpdateString("IndexName","PostedBy-Index")
    json.UpdateInt("Limit",3)
    json.UpdateBool("ConsistentRead",true)
    json.UpdateString("ProjectionExpression","Id, PostedBy, ReplyDateTime")
    json.UpdateString("KeyConditionExpression","Id = :v1 AND PostedBy BETWEEN :v2a AND :v2b")
    json.UpdateString("ExpressionAttributeValues.:v1.S","Amazon DynamoDB#DynamoDB Thread 1")
    json.UpdateString("ExpressionAttributeValues.:v2a.S","User A")
    json.UpdateString("ExpressionAttributeValues.:v2b.S","User C")
    json.UpdateString("ReturnConsumedCapacity","TOTAL")

    rest.AddHeader("Content-Type","application/x-amz-json-1.0")
    rest.AddHeader("X-Amz-Target","DynamoDB_20120810.Query")
    rest.AddHeader("Accept-Encoding","identity")

    sbRequestBody := chilkat.NewStringBuilder()
    json.EmitSb(sbRequestBody)
    sbResponseBody := chilkat.NewStringBuilder()
    success = rest.FullRequestSb("POST","/",sbRequestBody,sbResponseBody)
    if success != true {
        fmt.Println(rest.LastErrorText())
        rest.DisposeRest()
        authAws.DisposeAuthAws()
        json.DisposeJsonObject()
        sbRequestBody.DisposeStringBuilder()
        sbResponseBody.DisposeStringBuilder()
        return
    }

    respStatusCode := rest.ResponseStatusCode()
    fmt.Println("response status code = ", respStatusCode)
    if respStatusCode >= 400 {
        fmt.Println("Response Status Code = ", respStatusCode)
        fmt.Println("Response Header:")
        fmt.Println(rest.ResponseHeader())
        fmt.Println("Response Body:")
        fmt.Println(*sbResponseBody.GetAsString())
        rest.DisposeRest()
        authAws.DisposeAuthAws()
        json.DisposeJsonObject()
        sbRequestBody.DisposeStringBuilder()
        sbResponseBody.DisposeStringBuilder()
        return
    }

    jsonResponse := chilkat.NewJsonObject()
    jsonResponse.LoadSb(sbResponseBody)

    jsonResponse.SetEmitCompact(false)
    fmt.Println(*jsonResponse.Emit())

    // 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

    var ReplyDateTimeS *string = new(string)
    var PostedByS *string = new(string)
    var IdS *string = new(string)

    ConsumedCapacityCapacityUnits := jsonResponse.IntOf("ConsumedCapacity.CapacityUnits")
    ConsumedCapacityTableName := jsonResponse.StringOf("ConsumedCapacity.TableName")
    Count := jsonResponse.IntOf("Count")
    ScannedCount := jsonResponse.IntOf("ScannedCount")
    i := 0
    count_i := jsonResponse.SizeOfArray("Items")
    for i < count_i {
        jsonResponse.SetI(i)
        ReplyDateTimeS = jsonResponse.StringOf("Items[i].ReplyDateTime.S")
        PostedByS = jsonResponse.StringOf("Items[i].PostedBy.S")
        IdS = jsonResponse.StringOf("Items[i].Id.S")
        i = i + 1
    }


    rest.DisposeRest()
    authAws.DisposeAuthAws()
    json.DisposeJsonObject()
    sbRequestBody.DisposeStringBuilder()
    sbResponseBody.DisposeStringBuilder()
    jsonResponse.DisposeJsonObject()