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Events and metadata: how markets are assembled into matches ​

A single real-world match is usually several markets: "who wins", "total kills", "first Roshan". On chain these are independent pm_market_objects, but the client (Forecaster) shows them as one event card with bets on outcomes and a "N more lines" link. The grouping happens through metadata only — there are no special "parent" objects in consensus, and that is deliberate: the protocol stays minimal, while the grouping is set by the market creator at creation time.

The short model ​

  • Every market carries a free-form text field metadata (a JSON string in pm_create_market).
  • The node parses a whitelist of keys out of it and builds indexes; everything else is ignored.
  • Markets with the same event are "one event". A market without child is the front (parent) one, a market with child: 1 is a child line (a prop).
  • Forecaster: the "Events" tab groups active markets by event, shows the winner-line market as the front one, hides the children from the general feeds and reveals them on the event page.

The metadata keys the node indexes ​

The node extracts only these fields from metadata (other keys are not indexed, but remain in the raw JSON — clients can read them themselves):

KeyTypeWhat for
titlestringThe human-readable question of the market (the card headline).
categorystringThe listing section (esports, sports, crypto…) — the by_category index.
subcategorystringA refinement of the section (optional).
tagsarray or CSVTags for filters; the client reads the array market.metadata.tags, which the node rebuilds itself.
imagestring (URL)The card cover (a link, not hosted on chain).
descriptionstringShort resolution rules — "how the oracle will decide the outcome".
eventstring (slug)The event grouping key. All markets of one match set the same event.
event_titlestringThe human-readable name of the event ("Dota 2: MOUZ vs Vici — TI 2026").
child1 / trueA child line (a prop). Hidden from the category/tag feeds; visible on the event page.
banned_jurisdictionsarray or CSVThe jurisdiction filter for clients.
condition_idstringThe source's dedup identifier (for mirroring parsers).

Parsing rules: metadata must be a valid JSON object (non-JSON is simply not indexed); tags/banned_jurisdictions are accepted both as an array and as a CSV string; child is accepted as true, 1 or "1". Tags are matched case-insensitively.

How to designate the "parent" market ​

The parent is not designated explicitly — it is derived from the absence of child:

  1. Give all the markets of the match the same event (a stable slug: latin letters, hyphens — for example dota2-mouz-vg-2026-07-12) and the same event_title.
  2. For the main market of the match ("who wins" / moneyline) — do not set child. That is the parent: it stays visible in all feeds and becomes the face of the event card.
  3. For all the other lines (totals, handicaps, special markets) — child: 1. They disappear from the general feeds (no noise in the categories), but remain fully available on the event page and by direct link.

A minimal metadata example for three markets of one match:

json
// Parent (winner line) — WITHOUT child
{"title":"Will MOUZ beat Vici Gaming?","category":"esports","tags":["dota-2"],
 "event":"dota2-mouz-vg-2026-07-12","event_title":"Dota 2: MOUZ vs Vici Gaming"}

// Child line 1
{"title":"Total kills over 45.5 (map 1)?","category":"esports","tags":["dota-2"],
 "event":"dota2-mouz-vg-2026-07-12","event_title":"Dota 2: MOUZ vs Vici Gaming","child":1}

// Child line 2
{"title":"First Roshan — MOUZ?","category":"esports","tags":["dota-2"],
 "event":"dota2-mouz-vg-2026-07-12","event_title":"Dota 2: MOUZ vs Vici Gaming","child":1}

Important: event is immutable in practice — clients group by an exact string match, so pick the key before creating the markets and use it identically across all the lines of the match (case and hyphens matter).

What the node does ​

  • Builds the market's meta object (pm_market_meta) with the parsed fields and indexes: by category, by tags and by event (by_meta_event); the meta goes into the snapshot.
  • list_markets_by_category(...) hides children by default (hide_children = true, the 8th argument) — the feeds show only parents; pass false to see all the lines.
  • list_markets_by_event(event, from, limit) returns all the markets of the event — the parent and the children, with no filter. This is the API of the event page.
  • In listing rows event_title is returned at the top level, in the full market card — inside metadata; tags are rebuilt into an array by the node.

What Forecaster does with it ​

  • The "Events" tab (the sports-book view): active markets are grouped by event; the front market is the one whose headline looks like a winner line (winner / moneyline / to win), otherwise the first binary one; the card shows the outcomes with the current odds (a tap adds a leg to the coupon) and a "N more lines" link.
  • The event page #/event/<key> — all the lines of the match in one list (list_markets_by_event).
  • Cards show event_title above the question; the "Category › tags" breadcrumbs lead to the listings.
  • Category/tag feeds do not show child markets — the props live behind the event card.

The practical takeaway for a creator: correctly set event/event_title/child is the difference between "ten scattered markets making noise in the feed" and "one tidy match card with all the lines inside". Get the event key wrong and the lines will not group; forget child and the props will clutter the general feeds.

See also ​

VIZ Ledger