botnaut/src/dynamodb/DynamoAttachmentCache.js

Facebook Messenger Chatbot Framework

/*
 * @author Václav Oborník
 */
'use strict';

const AWS = require('aws-sdk');

/**
 * Conversation DynamoDB state storage
 */
class DynamoAttachmentCache {

    /**
     * @param {AWS.DynamoDB} dynamoDb
     * @param {string} tableName
     */
    constructor (dynamoDb, tableName) {

        this._documentClient = new AWS.DynamoDB.DocumentClient({
            service: dynamoDb,
            convertEmptyValues: true
        });

        this._tableName = tableName;
    }

    findAttachmentByUrl (url) {
        return this._documentClient.get({
            TableName: this._tableName,
            Key: { url }
        })
            .promise()
            .then((data) => {
                if (!data.Item) {
                    return null;
                }

                return data.Item.attachmentId;
            });
    }

    saveAttachmentId (url, attachmentId) {
        return this._documentClient.put({
            TableName: this._tableName,
            Item: { url, attachmentId }
        }).promise();
    }

}

module.exports = DynamoAttachmentCache;