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While the SDK is fully self-contained, there are two cases where it needs on-chain data to function. This guide will detail both of these cases, and offer a sample that you can use to fetch this data.

Unsurprisingly, the SDK needs some notion of a fungible token to be able to function. This immediately raises the question of where data about tokens comes from.

As an example, let's try to represent USDT in a format the SDK can work with. To do so, we need at least 3 pieces of data: a chainId, a token address, and how many decimals the token has. We also may be interested in the symbol and/or name of the token.

Identifying Data

The first two pieces of data — chainId and token address — must be provided by us. Thinking about it, this makes sense, as there's really no other way to unambiguously identify a token.

So, in the case of USDT, we know that the chainId is 126 (we're on mainnet), and the token address is 0xe5df458e0bb7020247d5e8c4f5fda70adaccff5318bb456bad8f7c1e3d2bf744. Note that it's very important to externally verify token addresses. Don't use addresses from sources you don't trust!

Required Data

The next piece of data we need is decimals.

Provided by the User

One option here is to simply pass in the correct value, which we may know is 6. At this point, we're ready to represent USDT as a Token:

import { ChainId, Token } from '@razorlabs/swap-sdk-core'
 
const chainId = ChainId.MAINNET
const tokenAddress = '0xe5df458e0bb7020247d5e8c4f5fda70adaccff5318bb456bad8f7c1e3d2bf744'
const decimals = 6
const symbol = 'tUSDT'
 
const DAI = new Token(chainId, tokenAddress, decimals, symbol)

If we don't know or don't want to hardcode the value, we could look it up ourselves via any method of retrieving on-chain data in a function that looks something like:

import { ChainId } from '@razorlabs/swap-sdk-core'
import { Aptos, AptosConfig } from '@aptos-labs/ts-sdk'
 
export function getNetworkRPCUrl(chainId: ChainId) {
  switch (chainId) {
    case ChainId.BARDOCK_TESTNET:
      return 'https://aptos.testnet.bardock.movementlabs.xyz/v1'
    default:
      return 'https://mainnet.movementnetwork.xyz/v1'
  }
}
 
export function getNetworkIndexerUrl(chainId: ChainId) {
  switch (chainId) {
    case ChainId.BARDOCK_TESTNET:
      return 'https://indexer.mainnet.movementnetwork.xyz/v1/graphql'
    default:
      return 'https://indexer.testnet.movementnetwork.xyz/v1/graphql'
  }
}
 
export function getDefaultProvider(chainId: ChainId) {
  const config = new AptosConfig({
    fullnode: getNetworkRPCUrl(chainId),
    indexer: getNetworkIndexerUrl(chainId),
  })
  const provider = new Aptos(config)
  return provider
}
 
async function getDecimals(chainId: ChainId, address: string): Promise<number> {
  const provider = getDefaultProvider(chainId).fungibleAsset;
  const tokenMetadata = await provider.getFungibleAssetMetadataByAssetType({ 
    assetType: address 
  });
  return tokenMetadata.decimals
}

Optional Data

Finally, we can talk about projectLink and name. Because these fields aren't used anywhere in the SDK itself, they're optional, and can be provided if you want to use them in your application. However, the SDK will not fetch them for you, so you'll have to provide them:

import { ChainId, Token } from '@razorlabs/swap-sdk-core'
 
const USDT = new Token(
  ChainId.MAINNET, 
  '0xe5df458e0bb7020247d5e8c4f5fda70adaccff5318bb456bad8f7c1e3d2bf744', 
  6, 
  'tUSDT', 
  'Tether USD',
  'https://tether.to'
)

Now that we've explored how to define a token, let's talk about pairs. To read more about what Razor DEX pairs are, see Pair

As an example, let's try to represent the DAI-MOVE pair.

Identifying Data

Each pair consists of two tokens (see previous section).

Required Data

The data we need is the reserves of the pair. To read more about reserves, see getReserves.

Provided by the User

One option here is to simply pass in values which we've fetched ourselves to create a Pair. In this example we use ethers to fetch the data directly from the blockchain:

import { ChainId, Token, CurrencyAmount } from '@razorlabs/swap-sdk-core'
import { Pair, WMOVE } from '@razorlabs/amm-sdk'
 
const DAI = new Token(ChainId.MAINNET, '0xfdae7b1bf4b0009f2373ff9e2a636f04bcc8b2d82563de84f4b511f19278c417', 6, 'tDAI')
 
function createPair(): Pair {
  const tokens = [DAI, WMOVE[ChainId.MAINNET]]
  const [token0, token1] = tokens[0].sortsBefore(tokens[1]) ? tokens : [tokens[1], tokens[0]]
  const currencyAmount0 = CurrencyAmount.fromRawAmount(token0, 100000)
  const currencyAmount1 = CurrencyAmount.fromRawAmount(token1, 109)
 
  const pair = new Pair(currencyAmount0, currencyAmount1)
  return pair
}

Note that these values can change as frequently as every block, and should be kept up-to-date.