116 lines
2.6 KiB
Markdown
116 lines
2.6 KiB
Markdown
# After [![Build Status][1]][2]
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Invoke callback after n calls
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## Status: production ready
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## Example
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```js
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var after = require("after")
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var db = require("./db") // some db.
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var updateUser = function (req, res) {
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// use after to run two tasks in parallel,
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// namely get request body and get session
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// then run updateUser with the results
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var next = after(2, updateUser)
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var results = {}
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getJSONBody(req, res, function (err, body) {
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if (err) return next(err)
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results.body = body
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next(null, results)
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})
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getSessionUser(req, res, function (err, user) {
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if (err) return next(err)
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results.user = user
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next(null, results)
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})
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// now do the thing!
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function updateUser(err, result) {
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if (err) {
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res.statusCode = 500
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return res.end("Unexpected Error")
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}
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if (!result.user || result.user.role !== "admin") {
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res.statusCode = 403
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return res.end("Permission Denied")
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}
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db.put("users:" + req.params.userId, result.body, function (err) {
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if (err) {
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res.statusCode = 500
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return res.end("Unexpected Error")
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}
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res.statusCode = 200
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res.end("Ok")
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})
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}
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}
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```
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## Naive Example
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```js
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var after = require("after")
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, next = after(3, logItWorks)
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next()
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next()
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next() // it works
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function logItWorks() {
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console.log("it works!")
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}
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```
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## Example with error handling
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```js
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var after = require("after")
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, next = after(3, logError)
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next()
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next(new Error("oops")) // logs oops
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next() // does nothing
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// This callback is only called once.
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// If there is an error the callback gets called immediately
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// this avoids the situation where errors get lost.
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function logError(err) {
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console.log(err)
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}
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```
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## Installation
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`npm install after`
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## Tests
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`npm test`
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## Contributors
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- Raynos
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- defunctzombie
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## MIT Licenced
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[1]: https://secure.travis-ci.org/Raynos/after.png
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[2]: http://travis-ci.org/Raynos/after
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[3]: http://raynos.org/blog/2/Flow-control-in-node.js
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[4]: http://stackoverflow.com/questions/6852059/determining-the-end-of-asynchronous-operations-javascript/6852307#6852307
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[5]: http://stackoverflow.com/questions/6869872/in-javascript-what-are-best-practices-for-executing-multiple-asynchronous-functi/6870031#6870031
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[6]: http://stackoverflow.com/questions/6864397/javascript-performance-long-running-tasks/6889419#6889419
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[7]: http://stackoverflow.com/questions/6597493/synchronous-database-queries-with-node-js/6620091#6620091
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[8]: http://github.com/Raynos/iterators
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[9]: http://github.com/Raynos/composite
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