Struct DeliveryTopic 

pub struct DeliveryTopic;

The key for MqttContext::topic.

It reads the topic borrowed through ctx.context(DeliveryTopic), and owned through the Ctx<DeliveryTopic> extractor, which is also what fixes a handler’s context type to MqttContext without a Context parameter.

Examples

use std::error::Error;

use ruststream::testing::TestApp;
use ruststream_rumqttc::prelude::*;
use serde::{Deserialize, Serialize};

#[derive(Deserialize, Serialize, Outgoing)]
struct Telemetry {
    temperature: f64,
}

#[derive(Debug, PartialEq, Deserialize, Serialize, Outgoing)]
#[outgoing(name = "alerts")]
struct Alert {
    topic: String,
}

#[subscriber(MqttFilter::new("devices/+/telemetry"))]
async fn watch(
    telemetry: &Telemetry,
    Ctx(topic): Ctx<DeliveryTopic>,
    Out(alerts): Out<impl Publisher>,
) -> HandlerOutcome {
    if telemetry.temperature <= 30.0 {
        return HandlerOutcome::ack();
    }
    if alerts.message(&Alert { topic }).publish().await.is_err() {
        return HandlerOutcome::retry();
    }
    HandlerOutcome::ack()
}

pub fn app() -> impl App {
    RustStream::new(AppInfo::new("telemetry", "0.1.0")).with_broker(
        MqttBroker::new("mqtt://localhost:1883", "telemetry-svc"),
        |b| {
            b.include(watch)
                .out(DefaultSlot, Publish::default())
                .out_retry(Publish::default())
                .to("devices/retry/telemetry")
                .build();
        },
    )
}

pub async fn an_alert_names_the_topic_not_the_filter() -> Result<(), Box<dyn Error>> {
    let tb = TestApp::start(app()).await?;

    tb.broker::<MqttBroker>()
        .message(&Telemetry { temperature: 31.5 })
        .to("devices/dev42/telemetry")
        .publish()
        .await?;

    tb.broker::<MqttBroker>()
        .published::<Alert>("alerts")
        .assert_called_once()
        .with(&Alert { topic: "devices/dev42/telemetry".to_owned() });
    tb.shutdown().await?;
    Ok(())
}

Trait Implementations

impl Clone for DeliveryTopic

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl ContextField for DeliveryTopic

type Context = MqttContext

The per-delivery context type this key reads from.

type Value = String

The owned value the key yields.

fn read(self, src: &MqttContext) -> String

Reads this key’s field out of src. Named apart from Field::get so a key implementing both traits stays unambiguous to call.

impl Copy for DeliveryTopic

impl Debug for DeliveryTopic

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for DeliveryTopic

fn default() -> Self

Returns the “default value” for a type.

impl Eq for DeliveryTopic

impl Field<MqttContext> for DeliveryTopic

type Value<'a> = &'a str

The value read through this key, borrowed from the source for 'a.

fn get(self, src: &MqttContext) -> &str

Reads this key’s field out of src.

impl PartialEq for DeliveryTopic

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for DeliveryTopic