Fetching Prices Using Rpc

If your requirements for calculating asset prices require a high grade of verifiability and leaves little room for client side calculation errors. You can fetch the prices for assets using the following on-chain rpc calls.

危险

These calls are currently not working on our mainnet and testnet, but will be supported in the 0.3.9 node release.

swaps.getSpotPrice()

This method fetches the current spot price given an assetIn and and assetOut at a given block(default is current block).

(
  poolId: u128 | Number | Uint8Array,
  assetIn: ZeitgeistPrimitivesAsset | AssetId | string | Uint8Array,
  assetOut: ZeitgeistPrimitivesAsset | AssetId | string | Uint8Array,
  withFees: bool | boolean | Uint8Array,
  at: Option<BlockHash> | null | Uint8Array | string,
) => Promise<u128>

Example

Here we are fetching the price for the AssetId { CategoricalOutcome: [0, 0] } in *ZTG at the current best block not including the swap fees.

const sdk: Sdk<RpcContext> = await create(localhostRpc());

const price = await sdk.api.rpc.swaps.getSpotPrice(
  0,
  { Ztg: null },
  { CategoricalOutcome: [0, 0] },
  false,
  null
);

console.log(new Decimal(price.toNumber()).div(ZTG).toNumber());

Full code snippet.

swaps.getSpotPrices()

This method fetches the spot prices given an assetIn and and assetOut for a range of blocks.

Usefull when you need a graph of prices over a range of blocks.

(
  poolId: u128 | Number | Uint8Array,
  assetIn: ZeitgeistPrimitivesAsset | AssetId | string | Uint8Array,
  assetOut: ZeitgeistPrimitivesAsset | AssetId | string | Uint8Array,
  withFees: bool | boolean | Uint8Array,
  blocks: Vec<u128> | Array<u128 | Number | Uint8Array>,
) => Promise<Vec<Balance>>

Example

Here we are fetching the price for the AssetId { CategoricalOutcome: [0, 0] } in *ZTG for the blocks 55, 56 and 57 not including the swap fees.

const sdk: Sdk<RpcContext> = await create(localhostRpc());

const prices = await sdk.api.rpc.swaps.getSpotPrices(
  0,
  { Ztg: null },
  { CategoricalOutcome: [0, 0] },
  false,
  [55, 56, 57]
);

prices.forEach((price) => {
  console.log(new Decimal(price.toNumber()).div(ZTG).toNumber());
});

Full code snippet.