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@dhavaln /index.js
Last active Jul 5, 2018

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Text To Audio Lambda Function using Polly - For Serverless Web API Article
const AWS = require('aws-sdk');
const Stream = require('stream')
const Fs = require('fs');
const convertTextToVoice = function(data, callback){
const polly = new AWS.Polly();
var params = {
OutputFormat: "mp3",
SampleRate: "8000",
Text: data.text,
TextType: "text",
VoiceId: data.voice
};
polly.synthesizeSpeech(params, callback);
}
const saveToS3 = function(postId, filePath, callback){
const S3 = new AWS.S3();
const readStream = Fs.createReadStream(filePath);
var params = {
Bucket : process.env.BUCKET_NAME,
Key : postId + ".mp3",
Body : readStream,
ACL: "public-read"
};
S3.upload(params, callback);
}
const deleteSQSMessage = function(receiptHandle){
const sqs = new AWS.SQS();
sqs.deleteMessage({
QueueUrl: process.env.SQS_URL,
ReceiptHandle: receiptHandle
});
}
const updateRecord = function(postId, status, url, callback){
const docClient = new AWS.DynamoDB.DocumentClient();
const params = {
TableName: process.env.DB_TABLE_NAME,
Key: {
"id": postId
},
UpdateExpression: "set #statusAtt = :s, #urlAtt=:u",
ExpressionAttributeNames: {
"#statusAtt": "status",
"#urlAtt": "url"
},
ExpressionAttributeValues:{
":s": status,
":u": url
}
};
docClient.update(params, callback);
}
exports.handler = (event, context, callback) => {
var postId = event["Records"][0].body;
var receiptHandle= event["Records"][0].receiptHandle;
deleteSQSMessage(receiptHandle);
console.log('Converting Post', postId);
const docClient = new AWS.DynamoDB.DocumentClient();
const params = {
TableName: process.env.DB_TABLE_NAME,
Key: {
"id": postId
}
};
docClient.get(params, (err, data) => {
if(err){
context.succeed({success: false, error: err});
}else{
console.log('Converting Text', data.Item.text, 'to voice', data.Item.voice);
convertTextToVoice(data.Item, (err, data) => {
if(err){
context.succeed({success: false, error: err});
}else{
if (data.AudioStream instanceof Buffer) {
const filePath = "/tmp/" + postId + ".mp3";
Fs.writeFile(filePath, data.AudioStream, function(err) {
if (err) {
context.succeed({success: false, error: err});
}else{
console.log('File ready to upload', filePath);
saveToS3(postId, filePath, (err, data) => {
if(err){
context.succeed({success: false, error: err});
}else{
updateRecord(postId, 'READY', data.Location, (err, data) => {
if (err) {
context.succeed({success: false, error: err});
}else{
context.succeed({success: true, data: data});
}
})
}
});
}
})
}
}
});
}
});
};
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