Go

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). Go

    success := false

    rest := chilkat.NewRest()

    // 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

    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": "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"
    // }

    json := chilkat.NewJsonObject()
    json.UpdateString("TableName","Thread")
    json.UpdateString("Key.ForumName.S","Amazon DynamoDB")
    json.UpdateString("Key.Subject.S","Maximum number of items?")
    json.UpdateString("UpdateExpression","set LastPostedBy = :val1")
    json.UpdateString("ConditionExpression","LastPostedBy = :val2")
    json.UpdateString("ExpressionAttributeValues.:val1.S","alice@example.com")
    json.UpdateString("ExpressionAttributeValues.:val2.S","fred@example.com")
    json.UpdateString("ReturnValues","ALL_NEW")

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

    // {
    //   "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

    var strVal *string = new(string)

    AttributesLastPostedByS := jsonResponse.StringOf("Attributes.LastPostedBy.S")
    AttributesForumNameS := jsonResponse.StringOf("Attributes.ForumName.S")
    AttributesLastPostDateTimeS := jsonResponse.StringOf("Attributes.LastPostDateTime.S")
    AttributesSubjectS := jsonResponse.StringOf("Attributes.Subject.S")
    AttributesViewsN := jsonResponse.StringOf("Attributes.Views.N")
    AttributesMessageS := jsonResponse.StringOf("Attributes.Message.S")
    i := 0
    count_i := jsonResponse.SizeOfArray("Attributes.Tags.SS")
    for i < count_i {
        jsonResponse.SetI(i)
        strVal = jsonResponse.StringOf("Attributes.Tags.SS[i]")
        i = i + 1
    }


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