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Bank module

This module keeps track of different accounts' balances (in-memory only) and facilitates transactions between those accounts.

Usage

Step 1: Setup

Edit your genesis.json file (default location ~/.cometbft/config/genesis.json) to update the app_state with initial account balances. This is a simple hash map of account IDs to balances (where each balance is a map of denomination and amount). Here's an example genesis.json file:

{
  "app_state": {
    "cosmos12xpmzmfpf7tn57xg93rne2hc2q26lcfql5efws": {
      "basecoin": "0x1000",
      "othercoin": "0x1000"
    },
    "cosmos1t2e0nyjhwn3revunvf2uperhftvhzu4euuzva9": {
      "basecoin": "0x250",
      "othercoin": "0x5000"
    },
    "cosmos1uawm90a5xm36kjmaazv89nxmfr8s8cyzkjqytd": {
      "acidcoin": "0x500"
    },
    "cosmos1ny9epydqnr7ymqhmgfvlshp3485cuqlmt7vsmf": {},
    "cosmos1xwgdxu4ahd9eevtfnq5f7w4td3rqnph4llnngw": {
      "acidcoin": "0x500",
      "basecoin": "0x0",
      "othercoin": "0x100"
    },
    "cosmos1mac8xqhun2c3y0njptdmmh3vy8nfjmtm6vua9u": {
      "basecoin": "0x1000"
    },
    "cosmos1wkvwnez6fkjn63xaz7nzpm4zxcd9cetqmyh2y8": {
      "basecoin": "0x1"
    },
    "cosmos166vcha998g7tl8j8cq0kwa8rfvm68cqmj88cff": {
      "basecoin": "0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF"
    }
  }
}

Step 2: Prepare a transfer transaction

We want to transfer some money from one of the accounts to the other. See tx.json for an example transaction that works with the above genesis app_state.

Step 3: Send the transaction

We will be sending our transaction via gaiad like so:

gaiad tx broadcast tests/fixtures/tx.json

Step 4: Query the account balances to ensure they've been updated

Query balance of receiver's account, i.e. cosmos1t2e0nyjhwn3revunvf2uperhftvhzu4euuzva9:

curl http://localhost:26657/abci_query?data=\"cosmos1t2e0nyjhwn3revunvf2uperhftvhzu4euuzva9\"
{
  "jsonrpc": "2.0",
  "id": -1,
  "result": {
    "response": {
      "code": 0,
      "log": "exists",
      "info": "",
      "index": "0",
      "key": "Y29zbW9zMXQyZTBueWpod24zcmV2dW52ZjJ1cGVyaGZ0dmh6dTRldXV6dmE5",
      "value": "eyJvdGhlcmNvaW4iOjYwMDAsImJhc2Vjb2luIjozNTB9",
      "proofOps": null,
      "height": "2",
      "codespace": ""
    }
  }
}

The value eyJvdGhlcmNvaW4iOjYwMDAsImJhc2Vjb2luIjozNTB9 is the base64-encoded string representation of the account's balance, which decodes to the string "{"othercoin":6000,"basecoin":350}" - this can be verified using echo "eyJvdGhlcmNvaW4iOjYwMDAsImJhc2Vjb2luIjozNTB9" | base64 -d.

Now, we query balance of sender's account (i.e. cosmos12xpmzmfpf7tn57xg93rne2hc2q26lcfql5efws):

curl http://localhost:26657/abci_query?data=\"cosmos12xpmzmfpf7tn57xg93rne2hc2q26lcfql5efws\"
{
  "jsonrpc": "2.0",
  "id": -1,
  "result": {
    "response": {
      "code": 0,
      "log": "exists",
      "info": "",
      "index": "0",
      "key": "Y29zbW9zMXNuZDVtNGgwd3Q1dXI1NWQ0N3ZweGxhMzg5cjJ4a2Y4ZGw2Zzl3",
      "value": "eyJiYXNlY29pbiI6OTAwLCJvdGhlcmNvaW4iOjB9",
      "proofOps": null,
      "height": "2",
      "codespace": ""
    }
  }
}

Just as before, value eyJiYXNlY29pbiI6OTAwLCJvdGhlcmNvaW4iOjB9 is the base64-encoded string representation of the account's balance, which decodes to the string "{"basecoin":900,"othercoin":0}".