Node module.export and recursion
I'm working on a node app, which is essentially a simple AWS SQS poller that has to sit and listen for new items in different queues.
Here is mine module.export
:
module.exports = {
readMessage: function(qParams, qType, tableName) {
logger.debug(qType);
SQS.receiveMessage(qParams, handleSqsResponse);
function handleSqsResponse (err, data) {
if(err) logger.error("handleSqsResponse error:" + err);
if (data && data.Messages) {
data.Messages.forEach(processMessage)
readMessage(); // continue reading until draining the queue (or UPTIME reached)
}
else{
logger.debug("no data in sqs.");
// process.exit();
}
}
// 'processing' is mainly writing to logs using winston. Could add here any transformations and transmission to remote systems
function processMessage(sqsMessage){
// Parse sqs messag
var msgObj = JSON.parse(sqsMessage.Body);
// Process
logger.info(msgObj.Message);
_.extend(qParams, { "ReceiptHandle": sqsMessage.ReceiptHandle });
dbMap[qType](msgObj, qParams, tableName);
}
}
}
The problem I am facing is trying to call again readMessage();
. I get an errorReferenceError: readMessage is not defined
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module.exports
is a simple object exposed to external modules that have a method readMessage
. readMessage()
should be module.exports.readMessage()
.
Also I would suggest creating a variable and then exporting it:
var obj = {
readMessage: function(qParams, qType, tableName) {
logger.debug(qType);
SQS.receiveMessage(qParams, handleSqsResponse);
function handleSqsResponse (err, data) {
if(err) logger.error("handleSqsResponse error:" + err);
if (data && data.Messages) {
data.Messages.forEach(processMessage)
obj.readMessage(); // continue reading until draining the queue (or UPTIME reached)
}
else{
logger.debug("no data in sqs.");
// process.exit();
}
}
// 'processing' is mainly writing to logs using winston. Could add here any transformations and transmission to remote systems
function processMessage(sqsMessage){
// Parse sqs messag
var msgObj = JSON.parse(sqsMessage.Body);
// Process
logger.info(msgObj.Message);
_.extend(qParams, { "ReceiptHandle": sqsMessage.ReceiptHandle });
dbMap[qType](msgObj, qParams, tableName);
}
}
}
module.exports = obj;
Please note that I only answered the question you asked. I have not taken into account any architectural issue related to the code.
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