Betting pallet

Overview

This pallet implements a basic protocol for decentralized betting.

Every account can create a match where rest of the users can bet. To create a match it is needed to place a deposit that will be returned after distribute the prizes.

The number of bets a user can create now are limited to 1.

Everyone can bet in the match, for a basic result: victory team 1, draw or victory team 2.

When the match is over a user with SUDO priviliges can set the result of the match.

A diagram:

⚠️ It is not a production-ready pallet, but a sample built for learning purposes. It is discouraged to use this code 'as-is' in a production runtime.

Configuration

Types

• RuntimeEvent – The overarching event type.
• Currency – The currency type.
• WeightInfo – Information on runtime weights.

Constants

• PalletId – Pallet ID. Used for account derivation.
• MaxTeamNameLength – Maximum length for team names.
• MatchDeposit - Deposite needed to create a match
• MaxBetsPerMatch – Maximum number of bets per match.

Extrinsics

create_match_to_bet

Creates a match to bet on. This function must be dispatched by a signed extrinsic. Emit an event on success: MatchCreated.

Parameters:

• origin – Origin for the call. Must be signed.
• team1 – Name of the first team.
• team2 – Name of the second team.
• start – Time when the match starts and a bet can not be placed (in blocks).
• lenght – Duration of the match (in blocks).

Errors:

• MatchAlreadyExists – A match for the specified values already exists.
• OriginHasAlreadyOpenMatch – An origin can only have one match open.
• TimeMatchOver – The match is created when the match time is over.

bet

Create bet for a match. Emit an event on success: BetPlaced.

Parameters:

• origin – Origin for the call. Must be signed.
• match_id – Id of the match, in our case the creator of the bet accountId.
• amount_to_bet – Amount placed for the bet.
• result – The result for the bet.

Errors:

• MatchDoesNotExist – A match selected for the bet doesn't exist.
• OriginHasAlreadyOpenMatch – If the match has started, betting is not allowed.
• TimeMatchOver – The match is created when the match time is over.
• MaxBets – The match has reach its betting limit.
• AlreadyBet – You already place the same bet in that match.

set_result

Notify the result of an existing match. The dispatch origin for this call must be Root. Emit an event on success: MatchResult.

Parameters:

• origin – Origin for the call. Must be signed.
• match_id – Id of the match, in our case the creator of the bet accountId.
• result – The result of the match.

Errors:

• MatchDoesNotExist – A match selected for the bet doesn't exist.
• TimeMatchNotOver – If the match is not over, set the result is not allowed.

distribute_winnings

When a match ends someone the owner of the match can distribute the money from the winers and delete the match. Distribute winnings: take all the prizes on the pot and distribute the prizes evenly.

Example:

Person A bets 10 UNITS on team1.

Person B bets 10 UNITS on team2.

Person C bets 30 UNITS on team1.

The total Pot is 50 UNITS.

If team1 is the winner, with weighted distribution the person A have to receive the 25% of the pot and the person C the 75%. The maths for this weighted distribution are simple: the amount that one deposit / the total amount of the winners deposit in the case of Person A = 10/40 = 0.25

Parameters:

• origin – Origin for the call. Must be signed.

Errors:

• MatchDoesNotExist – A match selected for the bet doesn't exist.
• MatchNotResult – The match still has not a result.

RPC

betting_getMatch

Get a match stored.

Parameters:

• match_id – ID of the match to retrieve (accountId of the creator).

How to add pallet-betting to a node

ℹ️ The pallet is compatible with Substrate version polkadot-v0.9.35.

ℹ️ This section is based on Substrate node template. Integrating pallet-betting with another node might look slightly different.

Runtime's Cargo.toml

Add pallet-betting, and the RPC runtime API, to dependencies.

[dependencies.pallet-betting]
version = "0.0.3"
default-features = false
git = "https://github.com/AlexD10S/substrate-betting.git"
branch = "main"

[dependencies.pallet-betting-rpc-runtime-api]
version = "0.0.1"
default-features = false
git = "https://github.com/AlexD10S/substrate-betting.git"
branch = "main"

Update the runtime's std feature:

std = [
    # --snip--
    "pallet-betting/std",
    "pallet-betting-rpc-runtime-api/std",
    # --snip--
]

Node's Cargo.toml

Add pallet-betting-rpc to dependencies.

[dependencies.pallet-betting-rpc]
version = "0.0.1"
default-features = false
git = "https://github.com/AlexD10S/substrate-betting.git"
branch = "main"

Runtime's lib.rs

Configure the betting pallet.

parameter_types! {
    pub const MatchDeposit: u64 = 10;
    pub const BettingPalletId: PalletId = PalletId(*b"py/betts");
}

impl pallet_betting::Config for Runtime {
    type RuntimeEvent = RuntimeEvent;
    type PalletId = BettingPalletId;
    type Currency = Balances;
    type MaxTeamNameLength = ConstU32<64>;
    type MaxBetsPerMatch = ConstU32<10>;
	  type MatchDeposit = MatchDeposit;
    type WeightInfo = pallet_betting::weights::SubstrateWeight<Runtime>;
}

Add configured pallets to the construct_runtime macro call.

construct_runtime!(
    pub enum Runtime where
        // --snip--
    {
        // --snip---
        Betting: pallet_betting,
        // --snip---
    }
);

Add the RPC implementation.

pub type TeamName = BoundedVec<u8, ConstU32<64>>;
pub type Bet = pallet_betting::Bet<AccountId, pallet_betting::MatchResult, Balance>;
pub type Match = pallet_betting::Match<BlockNumber, TeamName, BoundedVec<Bet, ConstU32<10>>, Balance>;

impl_runtime_apis! {
		impl pallet_betting_rpc_runtime_api::BettingApi<Block, AccountId, Match> for Runtime {
			fn get_match(match_id: AccountId) -> pallet_betting_rpc_runtime_api::RpcResult<Match>
			{
			  Betting::get_match(match_id)
			}
	}

Node's rpc.rs

Instantiate the RPC extension and merge it into the RPC module.

pub fn create_full<C, P>(
    deps: FullDeps<C, P>,
) -> Result<RpcModule<()>, Box<dyn std::error::Error + Send + Sync>>
where
    // --snip--
    C::Api: pallet_betting_rpc::BettingRuntimeApi<Block, Balance>,
{
    use pallet_betting_rpc::{Betting, BettingApiServer};
    // --snip--
    module.merge(Betting::new(client).into_rpc())?;
    Ok(module)
}