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Tournament Live Updates

Tournament and match live updates use Rails ActionCable at /cable.

Use these channels for website pages and beamer pages that need automatic updates when:

match scores change
match state changes
match positions change
group scores change
stages change
playoff matches are populated
follower-sync imports update a read-only follower tournament

This is websocket push, not webhook callback.

Transport

websocket endpoint: GET /cable
protocol: ActionCable
no auth token is required for read subscriptions
write operations still go through HTTP APIs

Frontend should:

Load initial state with HTTP.
Subscribe to relevant ActionCable channel.
Treat incoming websocket payloads as replacement snapshots.
Continue sending mutations through HTTP only.

Channels

TournamentChannel

Use this when page needs full tournament structure:

stages
groups
group scores
group matches
playoff stages
playoff matches
teams and advancing flags
timer fields
team action lists

Subscription identifier:

{
  "channel": "TournamentChannel",
  "tournament_id": 123
}

Payload:

{
  "type": "tournament.updated",
  "tournament_id": 123,
  "tournament": {
    "id": 123,
    "name": "Summer Cup",
    "code": "abc123",
    "public": true,
    "description": "Example tournament",
    "playoff_teams_amount": 4,
    "instant_finalists_amount": 4,
    "intermediate_round_participants_amount": 0,
    "timestamp": null,
    "timer_mode": null,
    "timer_reason": null,
    "timer_reason_text": null,
    "owner_username": "owner",
    "stages": [],
    "teams": [],
    "team_action_lists": []
  }
}

The nested tournament object has same public shape as:

GET /tournaments/:id

Frontend can replace cached tournament state with payload.tournament.

TournamentMatchesChannel

Use this when page only needs match cards/list updates:

match id
position
state
group identity
stage identity
teams
score rows

Subscription identifier for all matches:

{
  "channel": "TournamentMatchesChannel",
  "tournament_id": 123
}

Optional state filter:

{
  "channel": "TournamentMatchesChannel",
  "tournament_id": 123,
  "state": "in_progress"
}

Supported state values:

omitted / null: all matches
upcoming
single_team
not_ready
not_started
in_progress
finished
undecided

Payload:

{
  "type": "tournament_matches.updated",
  "tournament_id": 123,
  "state": null,
  "matches": [
    {
      "id": 456,
      "position": 0,
      "state": "in_progress",
      "group": {
        "id": 44,
        "number": 1
      },
      "stage": {
        "id": 33,
        "level": -1,
        "state": "in_progress"
      },
      "teams": [
        {
          "id": 10,
          "name": "Team A"
        },
        {
          "id": 11,
          "name": "Team B"
        }
      ],
      "match_scores": [
        {
          "id": 900,
          "points": 12,
          "hidden_points": 0,
          "team": {
            "id": 10,
            "name": "Team A"
          }
        },
        {
          "id": 901,
          "points": 8,
          "hidden_points": 0,
          "team": {
            "id": 11,
            "name": "Team B"
          }
        }
      ]
    }
  ]
}

The matches array has same shape as:

GET /tournaments/:id/matches
GET /tournaments/:id/matches?state=:state

Frontend can replace cached match list for that filter with payload.matches.

Initial Snapshot

Both channels transmit current snapshot immediately after subscription.

This means frontend can safely:

fetch over HTTP first, then subscribe
or subscribe and use first websocket message as live refresh

HTTP first is still recommended because it gives normal request/error/loading behavior.

Broadcast Sources

Broadcasts happen after successful backend writes/imports.

Covered direct HTTP mutations:

PATCH /match_scores/:id
PATCH /matches/:id
PATCH /matches/:id/swap
POST /groups/:group_id/matches
PATCH /stages/:id

Covered follower-sync mutation:

PATCH /tournaments/:id/sync_state

Practical effects:

score update broadcasts updated matches and updated group scores
finishing group stage broadcasts new playoff stages/matches
playoff match finish broadcasts populated next match
follower tournament subscribers get same updates after source sync import

Frontend Integration

Recommended tournament page flow:

Fetch GET /tournaments/:id.
Render tournament.
Subscribe to TournamentChannel.
On tournament.updated, replace tournament state with payload.tournament.
Keep writes as HTTP requests.

Recommended match-list/beamer flow:

Fetch GET /tournaments/:id/matches or state-filtered matches endpoint.
Render matches.
Subscribe to TournamentMatchesChannel with same state filter.
On tournament_matches.updated, replace that match list with payload.matches.
For multiple tabs/lists, use one subscription per filter you need.

Recommended update handling:

do not patch a single nested field from websocket payload
replace the full snapshot for that channel/filter
use match.id, group.id, stage.id, team.id, and match_score.id as stable keys
tolerate duplicate payloads
tolerate fast sequences like score update followed by match finish

ActionCable Message Example

Raw subscribe message:

{
  "command": "subscribe",
  "identifier": "{\"channel\":\"TournamentMatchesChannel\",\"tournament_id\":123,\"state\":\"in_progress\"}"
}

ActionCable wraps server payloads under message. Client libraries usually unwrap this for you.

Raw received frame shape:

{
  "identifier": "{\"channel\":\"TournamentMatchesChannel\",\"tournament_id\":123,\"state\":\"in_progress\"}",
  "message": {
    "type": "tournament_matches.updated",
    "tournament_id": 123,
    "state": "in_progress",
    "matches": []
  }
}

Relationship To Other Live Channels

Other specialized channels still exist:

TournamentTimersChannel: timer-only payloads
TournamentBeamersChannel: beamer display config payloads
TournamentTeamActionListsChannel: team action list payloads

Use TournamentChannel when full tournament state is needed. Use specialized channels when frontend wants smaller, focused payloads.

Tests

Covered by:

6.6 KiB Raw Blame History