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batchWriteItemでデータ追加

Last updated at Posted at 2016-09-04

やりたいこと

DynamoDBに対してbatchWriteItemを使用して、データを追加。

注意点

1リクエストで25件まで
25件の登録の一部がスループットエラーの場合、UnprocessedItemsにエラーデータが格納されるのでリトライが必要。

実装

'use strict';

let util = require('util');
let aws = require('aws-sdk');

aws.config.loadFromPath('./config/credentials.json');
let dynamodb = new aws.DynamoDB({apiVersion: '2012-08-10'});

// 格納データ作成
let writeFuncs = new Array();
for (let i = 0; i < 5; i++) {
    let putRequests = [];
    for (let l = 0; l < 5; l++) {
        let id = (i + 1) * l;
        putRequests[l] = {
            PutRequest : {
                Item : {
                    'id' : {'S' : id.toString()},
                    'name' : {'S' : 'name' + id}
                }
            }
        }
    }

    function doWriteItemCall() {
        return doWriteItem({
                RequestItems : {
                    "users" : putRequests
                }
            });
    }

    writeFuncs[i] = doWriteItemCall;
}
writeFuncs[5] = function () {
    console.log('end');
}
// データ追加
console.log('start');
sequenceTasks(writeFuncs);

function doWriteItem(params) {
    console.log('doWriteItem call');

    return new Promise(function (resolve, reject) {
        let callback = batchWriteItemCallback.bind(null, resolve, reject);
        dynamodb
            .batchWriteItem(params)
            .on('complete', callback)
            .send();
    });
}


function batchWriteItemCallback(resolve, reject, response) {
    let error = response.error;
    let data = response.data;
    console.log(error, data);
    let callback = batchWriteItemCallback.bind(null, resolve,reject);

    if (error) {
        if (error.retryable) {
            dynamodb
                .batchWriteItem(response.request.param)
                .on('complete', callback)
                .send();
        } else {
            reject(error);
        }
    } else if('users' in data.UnprocessedItems) {
        let params = {};
        params.RequestItems = data.UnprocessedItems;
        dynamodb
            .batchWriteItem(params)
            .on('complete', callback)
            .send();
    } else {
        resolve();
    }
}

function sequenceTasks(tasks) {
    function recordValue(results, value) {
        results.push(value);
        return results;
    }
    // let pushValue = recordValue.bind(null, []);
    return tasks.reduce(function (promise, task) {
        console.log('reduce call');
        return promise
            .then(task)
            // .then(pushValue)
            ;
    }, Promise.resolve());
}

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