feed

GTFS Realtime Feed

Module for working with GTFS Realtime feeds. Provides functions to decode and query realtime feed data.

Example

import gtfs/realtime/feed
import gleam/io

pub fn main() {
  // Decode a feed from bytes
  let assert Ok(feed_message) = feed.decode(my_protobuf_bytes)

  // Get all trip updates
  let updates = feed.get_trip_updates(feed_message)

  // Get all alerts
  let alerts = feed.get_alerts(feed_message)
}

Types

FetchError

</>

Error type for HTTP fetch operations

pub type FetchError {
  HttpError(String)
  StatusError(Int)
  DecodeError(protobin.ParseError)
}

Constructors

```
HttpError(String)
```
HTTP request failed
```
StatusError(Int)
```
Response was not successful (non-2xx status)
```
DecodeError(protobin.ParseError)
```
Protocol Buffer decoding failed

Values

alert_count

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pub fn alert_count(feed: types.FeedMessage) -> Int

Get count of alerts in the feed

decode

</>

pub fn decode(
  data: BitArray,
) -> Result(types.FeedMessage, protobin.ParseError)

Decode a GTFS Realtime feed from protobuf binary data

entity_count

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pub fn entity_count(feed: types.FeedMessage) -> Int

Get the total number of entities in the feed

fetch

</>

pub fn fetch(
  url: String,
) -> Result(types.FeedMessage, FetchError)

Fetch and decode a GTFS Realtime feed from a URL

Example

import gtfs/realtime/feed

pub fn main() {
  case feed.fetch("https://api.transit.example.com/gtfs-rt/vehiclepositions") {
    Ok(feed_message) -> {
      let vehicles = feed.get_vehicle_positions(feed_message)
      // Process vehicles...
    }
    Error(feed.HttpError(msg)) -> io.println("HTTP error: " <> msg)
    Error(feed.StatusError(code)) -> io.println("Bad status: " <> int.to_string(code))
    Error(feed.DecodeError(_)) -> io.println("Failed to decode protobuf")
  }
}

from_bytes

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pub fn from_bytes(
  data: BitArray,
) -> Result(types.FeedMessage, protobin.ParseError)

Decode a GTFS Realtime feed from raw bytes (alias for decode)

get_alerts

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pub fn get_alerts(feed: types.FeedMessage) -> List(types.Alert)

Get all alerts from a feed

get_alerts_for_route

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pub fn get_alerts_for_route(
  feed: types.FeedMessage,
  route_id: String,
) -> List(types.Alert)

Get all alerts affecting a specific route

get_alerts_for_stop

</>

pub fn get_alerts_for_stop(
  feed: types.FeedMessage,
  stop_id: String,
) -> List(types.Alert)

Get all alerts affecting a specific stop

get_entity

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pub fn get_entity(
  feed: types.FeedMessage,
  id: String,
) -> option.Option(types.FeedEntity)

Get a specific entity by ID

get_timestamp

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pub fn get_timestamp(
  feed: types.FeedMessage,
) -> option.Option(Int)

Get the feed timestamp (when the content was created)

get_trip_delay

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pub fn get_trip_delay(
  feed: types.FeedMessage,
  trip_id: String,
) -> option.Option(Int)

Get delay for a specific trip (in seconds, positive = late)

get_trip_update

</>

pub fn get_trip_update(
  feed: types.FeedMessage,
  trip_id: String,
) -> option.Option(types.TripUpdate)

Get trip update for a specific trip ID

get_trip_updates

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pub fn get_trip_updates(
  feed: types.FeedMessage,
) -> List(types.TripUpdate)

Get all trip updates from a feed

get_vehicle_position

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pub fn get_vehicle_position(
  feed: types.FeedMessage,
  vehicle_id: String,
) -> option.Option(types.VehiclePosition)

Get vehicle position for a specific vehicle ID

get_vehicle_positions

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pub fn get_vehicle_positions(
  feed: types.FeedMessage,
) -> List(types.VehiclePosition)

Get all vehicle positions from a feed

get_vehicles_on_route

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pub fn get_vehicles_on_route(
  feed: types.FeedMessage,
  route_id: String,
) -> List(types.VehiclePosition)

Get all vehicle positions for a specific route

get_version

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pub fn get_version(feed: types.FeedMessage) -> String

Get the GTFS Realtime version

is_full_dataset

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pub fn is_full_dataset(feed: types.FeedMessage) -> Bool

Check if the feed is a full dataset or differential update

trip_update_count

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pub fn trip_update_count(feed: types.FeedMessage) -> Int

Get count of trip updates in the feed

vehicle_position_count

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pub fn vehicle_position_count(feed: types.FeedMessage) -> Int

Get count of vehicle positions in the feed