Add a table

In this tutorial you add a table of historical counter values and the time in which the counter reached those values. For the sake of simplicity, we will implement this in the increment function rather than use a storage hook.

Setup

Create a new MUD application from the template.

Modify the MUD configuration file

1. In an editor, open packages/contracts/mud.config.ts and add a table definition for History.

   mud.config.ts

   import { mudConfig } from "@latticexyz/world/register";
    
   export default mudConfig({
     tables: {
       Counter: {
         keySchema: {},
         valueSchema: "uint32",
       },
       History: {
         keySchema: {
           counterValue: "uint32",
         },
         valueSchema: {
           blockNumber: "uint256",
           time: "uint256",
         },
       },
     },
   });

2. Run this command in packages/contracts to regenerate the table libraries.

   pnpm build:mud

Update IncrementSystem

1. In an editor, open packages/contracts/src/systems/IncrementSystem.sol.

   • Modify the second import line to import History.
   • Modify the increment function to also update History. To see the exact functions that are available, you can look at packages/contracts/src/codegen/tables/History.sol (that is the reason we ran pnpm build:mud to recreate it already).

// SPDX-License-Identifier: MIT
pragma solidity >=0.8.0;
 
import { System } from "@latticexyz/world/src/System.sol";
import { Counter, History, HistoryData } from "../codegen/index.sol";
 
contract IncrementSystem is System {
  function increment() public returns (uint32) {
    uint32 counter = Counter.get();
    uint32 newValue = counter + 1;
    Counter.set(newValue);
    History.set(newValue, block.number, block.timestamp);
    return newValue;
  }
}

import { Counter, History, HistoryData } from "../codegen/index.sol";

struct HistoryData {
  uint256 blockNumber;
  uint256 time;
}

History.set(newValue, block.number, block.timestamp);

2. Run this command in packages/contracts to rebuild everything this package produces.

   pnpm build

Update the user interface

You can already run the application and see in the MUD Dev Tools that there is a :History table and it gets updates when you click Increment. Click the Store data tab and select the table :History.

However, you can also add the history to the user interface. The directions here apply to the vanilla client template, if you use anything else you'll need to modify them as appropriate.

1. Edit packages/client/src/index.ts.

   • Import some additional definitions.
   • Use components.History.update$.subscribe to update the history.
   index.ts

   import { setup } from "./mud/setup";
   import mudConfig from "contracts/mud.config";
   import { encodeEntity, singletonEntity } from "@latticexyz/store-sync/recs";
   import { getComponentValue } from "@latticexyz/recs";
    
   const {
     components,
     systemCalls: { increment },
     network,
   } = await setup();
    
   // Components expose a stream that triggers when the component is updated.
   components.Counter.update$.subscribe((update) => {
     const [nextValue, prevValue] = update.value;
     console.log("Counter updated", update, { nextValue, prevValue });
     document.getElementById("counter")!.innerHTML = String(nextValue?.value ?? "unset");
   });
    
   components.History.update$.subscribe((update) => {
     const History = components.History;
     var table = "<tr><th>Counter</th><th>Block</th><th>Time</th></tr>";
     for (var i = 0; i <= getComponentValue(components.Counter, singletonEntity).value; i++) {
       const key = encodeEntity(History.metadata.keySchema, { counterValue: i });
       const value = getComponentValue(History, key);
       if (value)
         table +=
           `<tr><td>${i}</td><td>${value.blockNumber}</td>` + `<td>${new Date(Number(value.time) * 1000)}</td></tr>\n`;
     }
     document.getElementById("history")!.innerHTML = `<table border>${table}</table>`;
   });
    
   // Just for demonstration purposes: we create a global function that can be
   // called to invoke the Increment system contract via the world.
   // (See IncrementSystem.sol)
   (window as any).increment = async () => {
     console.log("new counter value:", await increment());
   };
    
   if (import.meta.env.DEV) {
     const { mount: mountDevTools } = await import("@latticexyz/dev-tools");
     mountDevTools({
       config: mudConfig,
       publicClient: network.publicClient,
       walletClient: network.walletClient,
       latestBlock$: network.latestBlock$,
       storedBlockLogs$: network.storedBlockLogs$,
       worldAddress: network.worldContract.address,
       worldAbi: network.worldContract.abi,
       write$: network.write$,
       recsWorld: network.world,
     });
   }

components.History.update$.subscribe((update) => {

  const History = components.History;
  var table = "<tr><th>Counter</th><th>Block</th><th>Time</th></tr>";
  for(var i=0; i<=getComponentValue(components.Counter,singletonEntity).value; i++) {

const key = encodeEntity(History.metadata.keySchema, { counterValue: i });
const value = getComponentValue(History, key);

if (value)
  table += `<tr><td>${i}</td><td>${value.blockNumber}</td>` + `<td>${new Date(Number(value.time) * 1000)}</td></tr>\n`;

  }
  document.getElementById("history")!.innerHTML = `<table border>${table}</table>`
});

2. Edit packages/clients/index.html to add a text area for the history.

   index.html

   <!doctype html>
   <html lang="en">
     <head>
       <meta charset="UTF-8" />
       <meta name="viewport" content="width=device-width, initial-scale=1.0" />
       <title>a minimal MUD client</title>
     </head>
     <body>
       <script type="module" src="/src/index.ts"></script>
       <div>Counter: <span id="counter">0</span></div>
       <button onclick="window.increment()">Increment</button>
       <hr />
       <h2>History</h2>
       <div id="history"></div>
     </body>
   </html>

3. Run pnpm dev in the application's root directory (or restart it if already running), browse to the app URL, and click Increment a few times. See that the history table gets populated.