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. Use the vanilla template.

pnpm create mud@latest tutorial --template vanilla
cd tutorial

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 { defineWorld } from "@latticexyz/world";
    
   export default defineWorld({
     namespace: "app",
     tables: {
       Counter: {
         schema: {
           value: "uint32",
         },
         key: [],
       },
       History: {
         schema: {
           counterValue: "uint32",
           blockNumber: "uint256",
           time: "uint256",
         },
         key: ["counterValue"],
       },
     },
   });

2. Run this command to regenerate the table libraries.

   (cd packages/contracts; pnpm mud tablegen)

Update IncrementSystem

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 to recreate it already).

// SPDX-License-Identifier: MIT
pragma solidity >=0.8.0;
 
import { System } from "@latticexyz/world/src/System.sol";
import { Counter, History } 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 } from "../codegen/index.sol";

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

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 updated when you click Increment. Click the Components tab and select the History component.

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>`;
   });
    
   // Attach the increment function to the html element with ID `incrementButton` (if it exists)
   document.querySelector("#incrementButton")?.addEventListener("click", 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 id="incrementButton">Increment</button>
       <hr />
       <h2>History</h2>
       <div id="history"></div>
     </body>
   </html>

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