carotte/publisher

Types

HeaderList

opaque </>

pub opaque type HeaderList

HeaderValue

</>

pub type HeaderValue {
  BoolHeader(Bool)
  FloatHeader(Float)
  IntHeader(Int)
  StringHeader(String)
  ListHeader(List(HeaderValue))
}

Constructors

```
BoolHeader(Bool)
```
```
FloatHeader(Float)
```
```
IntHeader(Int)
```
```
StringHeader(String)
```
```
ListHeader(List(HeaderValue))
```

PublishOption

</>

pub type PublishOption {
  Mandatory(Bool)
  ContentType(String)
  ContentEncoding(String)
  Headers(HeaderList)
  Persistent(Bool)
  CorrelationId(String)
  Priority(Int)
  ReplyTo(String)
  Expiration(String)
  MessageId(String)
  Timestamp(Int)
  Type(String)
  UserId(String)
  AppId(String)
}

Constructors

```
Mandatory(Bool)
```
If set, returns an error if the broker can’t route the message to a queue
```
ContentType(String)
```
MIME Content type
```
ContentEncoding(String)
```
MIME Content encoding
```
Headers(HeaderList)
```
Headers to attach to the message. Use headers_from_list to create headers for sending, and headers_to_list to read headers from received messages.
```
Persistent(Bool)
```
If set, uses persistent delivery mode. Messages marked as persistent that are delivered to durable queues will be logged to disk
```
CorrelationId(String)
```
Arbitrary application-specific message identifier
```
Priority(Int)
```
Message priority, ranging from 0 to 9
```
ReplyTo(String)
```
Name of the reply queue
```
Expiration(String)
```
How long the message is valid (in milliseconds)
```
MessageId(String)
```
Message identifier
```
Timestamp(Int)
```
timestamp associated with this message (epoch time)
```
Type(String)
```
Message type
```
UserId(String)
```
Creating user ID. RabbitMQ will validate this against the active connection user
```
AppId(String)
```
Application ID

Values

empty_headers

</>

pub fn empty_headers() -> HeaderList

Create an empty HeaderList. Useful for pattern matching or when no headers are needed.

headers_from_list

</>

pub fn headers_from_list(
  list: List(#(String, HeaderValue)),
) -> HeaderList

Create a HeaderList from a list of name-value pairs. Use this to construct headers for messages.

Example

let headers = headers_from_list([
  #("user_id", StringHeader("123")),
  #("retry_count", IntHeader(3)),
  #("is_test", BoolHeader(True)),
])

headers_to_list

</>

pub fn headers_to_list(
  headers: HeaderList,
) -> List(#(String, HeaderValue))

Convert a HeaderList back to a list of name-value pairs. Use this to read headers from received messages.

Example

case queue.subscribe(channel, "my_queue", fn(payload, _deliver) {
  let headers = publisher.headers_to_list(payload.headers)
  // headers: List(#(String, HeaderValue))
})

publish

</>

pub fn publish(
  channel channel: channel.Channel,
  exchange exchange: String,
  routing_key routing_key: String,
  payload payload: String,
  options options: List(PublishOption),
) -> Result(Nil, carotte.CarotteError)

Publish a message ‘payload’ to an exchange The routing_key is used to filter messages from the exchange The options are used to set message properties