Data Sources

• Mainnet assets
  • L1 - etherscan
  • L2 - blockscout
• Testnet assets
  • Hard coded
• Prices and chart data
  • L1 - coingecko
    • map from etherscan to coin gecko token using token address
  • L2 - honey swap/coingecko
    • map from block scout to honey swap token using token address
    • map honey swap token to coin gecko token using token symbol
    • for some tokens, we get the usdBalance using the exchange rate API in the SDK
• Balances
  • Balance checker contracts
  • GitHub - wbobeirne/eth-balance-checker: Solidity contract to batch balance checks in one call
  • We deployed our own instances of this contract for each network and store the address of the deployed instance within the SDK
• Prepaid cards/depots/merchant safes
  • L1 - N/A
  • L2 - card pay SDK
• Collectibles
  • L1 - Opensea
  • L2 - N/A
• Transactions
  • L1 (main net) - Zerion
  • L1 (testnet) - Local storage
  • L2 - The graph
• Currency conversion rates
  • Fixer API and then stored in Redux
  • Coingecko automatically handles currency conversion for prices, but we use this when we need to manually do a conversion
  • cardwallet/useLoadCurrencyConversionRates.js at develop · cardstack/cardwallet · GitHub
• Historical pricing
  • cardwallet/historical-pricing-service.ts at develop · cardstack/cardwallet · GitHub
  • Used for historical transaction data on L2, Zerion handles this for us in L1
  • min-api
  • Implementing local caching so we never request the same historical price twice

---

In an ideal world, we’d be able to get all asset data on the list screen in a single GraphQL query and cache it using Apollo client, with built in loading/error handling. This could look something like the following:

model Price {
 tokenAddress: string;
 nativeCurrency: string;
 amount: number;
}

model Token {
  name: string;
  symbol: string;
  address: string;
  decimals: number;
  price: Price;
}

model Balance {
  accountAddress: string;
  account: Account;
  amount: number;
  tokenAddress: string;
  token: Token;
}

model PrepaidCard {
  id: string;
  balances: Balance[];
  ...
}

model Depot {
  id: string;
  balances: Balance[];
  ...
}

model MerchantSafe {
  id: string;
  balances: Balance[];
  ...
}

model Account {
  assetBalances: Balance[];
  prepaidCards: PrepaidCard[];
  depot: Depot;
  merchantSafes: MerchantSafe[];
}

account(address: $id, nativeCurrency: $nativeCurrency) {
  assetBalances {
    amount
    token {
      name
      symbol
      address
      price {
        amount
      }
    }
  }
  prepaidCards {
    id
    balances {
      amount
      token {
        name
        symbol
        address
        price {
          amount
        }
      }
    }
    ...
  }
  depot {
    id
    balances {
      amount
      token {
        name
        symbol
        address
        price {
          amount
        }
      }
    }
    ...
  }
  merchantSafe {
    id
    balances {
      amount
      token {
        name
        symbol
        address
        price {
          amount
        }
      }
    }
    ...
  }
}