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feat: preUnsubscribe handler #605

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feat: preUnsubscribe handler #605

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6 changes: 6 additions & 0 deletions aedes.js
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,7 @@ const defaultOptions = {
authorizePublish: defaultAuthorizePublish,
authorizeSubscribe: defaultAuthorizeSubscribe,
authorizeForward: defaultAuthorizeForward,
preUnsubscribe: defaultPreUnsubscribe,
published: defaultPublished,
trustProxy: false,
trustedProxies: [],
Expand Down Expand Up @@ -69,6 +70,7 @@ function Aedes (opts) {
this.authorizePublish = opts.authorizePublish
this.authorizeSubscribe = opts.authorizeSubscribe
this.authorizeForward = opts.authorizeForward
this.preUnsubscribe = opts.preUnsubscribe
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@robertsLando robertsLando Apr 1, 2021

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You should add a defaultPreSubscribe function and add it to defaultOptions

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@chfritz chfritz Apr 1, 2021

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Ah, yes, good point. Thanks, done.

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@robertsLando robertsLando Apr 1, 2021

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Should that allow some async stuff like the others do? maybe adding a callbackk to it?

this.published = opts.published

this.decodeProtocol = opts.decodeProtocol
Expand Down Expand Up @@ -337,6 +339,10 @@ function defaultAuthorizeForward (client, packet) {
return packet
}

function defaultPreUnsubscribe (client, packet, callback) {
callback(client, packet)
}

function defaultPublished (packet, client, callback) {
callback(null)
}
Expand Down
27 changes: 27 additions & 0 deletions docs/Aedes.md
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Expand Up @@ -29,6 +29,7 @@
- [Handler: authorizePublish (client, packet, callback)](#handler-authorizepublish-client-packet-callback)
- [Handler: authorizeSubscribe (client, subscription, callback)](#handler-authorizesubscribe-client-subscription-callback)
- [Handler: authorizeForward (client, packet)](#handler-authorizeforward-client-packet)
- [Handler: preUnsubscribe (client, packet, callback)](#handler-preunsubscribe-client-packet-callback)
- [Handler: published (packet, client, callback)](#handler-published-packet-client-callback)

## new Aedes([options]) / new Aedes.Server([options])
Expand Down Expand Up @@ -386,6 +387,31 @@ aedes.authorizeForward = function (client, packet) {
}
```

## Handler: preUnsubscribe (client, packet, callback)

- client: [`<Client>`](./Client.md)
- packet: `<aedes-packet>` & [`UNSUBSCRIBE`][UNSUBSCRIBE]
- callback: `<Function>`

Invoked when a client unsubscribes from topics. Just like
[`authorizeSubscribe`](#handler-authorizesubscribe-client-subscription-callback), this function allows modifying the topics before executing the unsubscribe. This may be needed in cases where topics were modified in `authorizeSubscribe`. For example:

```js
aedes.authorizeSubscribe = (client, subscription, callback) => {
// overwrite subscription: force client to its namespace
subscription.topic = `/${client.id}/${subscription.topic}`;
callback(null, subscription);
}

aedes.preUnsubscribe = (client, packet, callback) => {
// overwrite unsubscriptions: force client to its namespace
for (let i in packet.unsubscriptions) {
packet.unsubscriptions[i] = `/${client.id}/${packet.unsubscriptions[i]}`;
}
callback(packet, client)
}
```

## Handler: published (packet, client, callback)

- packet: `<aedes-packet>` & [`PUBLISH`][PUBLISH]
Expand All @@ -397,6 +423,7 @@ same as [`Event: publish`](#event-publish), but provides a backpressure function
[CONNECT]: https://github.com/mqttjs/mqtt-packet#connect
[CONNACK]: https://github.com/mqttjs/mqtt-packet#connack
[SUBSCRIBE]: https://github.com/mqttjs/mqtt-packet#subscribe
[UNSUBSCRIBE]: https://github.com/mqttjs/mqtt-packet#unsubscribe
[PINGREQ]: https://github.com/mqttjs/mqtt-packet#pingreq
[PUBLISH]: https://github.com/mqttjs/mqtt-packet#publish
[PUBREL]: https://github.com/mqttjs/mqtt-packet#pubrel
8 changes: 7 additions & 1 deletion lib/handlers/unsubscribe.js
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Expand Up @@ -14,8 +14,14 @@ function UnsubscribeState (client, packet, finish) {
this.finish = finish
}

function preUnsubscribe (client, packet, done) {
client.broker.preUnsubscribe(client, packet, (c, p) =>
handleUnsubscribe(c, p, done))
}

function handleUnsubscribe (client, packet, done) {
const broker = client.broker

const unsubscriptions = packet.unsubscriptions
let err

Expand Down Expand Up @@ -101,4 +107,4 @@ function completeUnsubscribe (err) {

function noop () {}

module.exports = handleUnsubscribe
module.exports = preUnsubscribe