[feature] default values for fields

[Sofianel5]

Databases and ORMs generally allow fields to be defined with a default value. Doing this now in ponder is a little janky. For example, I have a schema where I want to keep track of points users accrue (all users start at 0).

Current Implementation

In order to implement this right now, I need to either explicitly set points to 0 whenever I create a new user or set points to be an optional value. The former would be extremely tedious as I create new accounts in many different watchers, and its much cleaner to just do

await Account.upsert({
    id: event.args.from,
});

then explicitly set points to 0 across all watchers that create accounts but have nothing to do with points. However the latter requires consumers of the indexer to explicitly cast null to 0 on the points field of accounts. Currently, my has to do this.

// schema.ponder.ts
export default createSchema((p) => ({
  Account: p.createTable({
    id: p.hex(),
    tokens: p.many("TokenBalance.ownerId"),
    points: p.bigint().optional(),
    transferFromEvents: p.many("TransferEvent.fromId"),
    transferToEvents: p.many("TransferEvent.toId"),
  }),
}));

// Contract.ts
ponder.on("Contract:PointEarned", async ({ event, context }) => {
  const { Account } = context.db;

  await Account.upsert({
    id: event.args.user,
    update: ({ current }) => ({
      points: (current.points ?? 0n) + 1n,
    }),
  });
});

Usage Example

Here's an example of what this might look like in ponder.schema.ts with the requested feature.

import { createSchema } from "@ponder/core";

export default createSchema((p) => ({
  Account: p.createTable({
    id: p.hex(),
    tokens: p.many("TokenBalance.ownerId"),
    points: p.bigint(0n), // Set a default value of 0 for points
    transferFromEvents: p.many("TransferEvent.fromId"),
    transferToEvents: p.many("TransferEvent.toId"),
  }),
}));

Then I don't need to change anything about my indexer code except increment the points counter.

ponder.on("Contract:PointEarned", async ({ event, context }) => {
  const { Account } = context.db;

  await Account.upsert({
    id: event.args.user,
    update: ({ current }) => ({
      points: current.points + 1n,
    }),
  });
});

[0xOlias]

Great idea, this would be a nice quality of life improvement. I propose a slightly different API:

import { createSchema } from "@ponder/core";

export default createSchema((p) => ({
  Account: p.createTable({
    id: p.hex(),
    tokens: p.many("TokenBalance.ownerId"),
    points: p.bigint().default(0n), // Set a default value of 0 for points
    // ...
  }),
}));

which would align better with the existing .optional() and .references(...) builder pattern we have.

Implementation-wise, we should be able to use a SQL DEFAULT for both SQLite and Postgres. At a type level, adding .default(...) would make the column optional on insert, but required on select.

Thoughts @Sofianel5 ?

[Sofianel5]

My initial thought to just supply it as a value to the type function made more sense to me initially, but with the optional() and .references() builder pattern I'd agree that a .default(x) would fit better within the system.