Best practice to store "callbacks" in database?

For example, let's say I have a JS interface for game achievement:

type Achievement = {
  title: string;

  // based on user's game data, return whether the criteria of this achievement is met or not
  isCriteriaMet: (ctx: UserGameData) => boolean;
  
  // if criteria is met, reward user by running this function to mutate user's data
  reward: () => void;
}

type Achievement = {
  title: string;

  // based on user's game data, return whether the criteria of this achievement is met or not
  isCriteriaMet: (ctx: UserGameData) => boolean;
  
  // if criteria is met, reward user by running this function to mutate user's data
  reward: () => void;
}

What is the best practice to represent this in Convex DB? Or in any DB? My thought is to store reference to a query function (in my code) in isCriteriaMet field; store reference to a mutation function in reward field. Or maybe just references to helper functions with context? If implemented this way, is there a Convex internal API where I can sync the list of query/mutation functions I defined in my code to the Convex DB, so I can safely reference them in another table?

2 Replies

Convex Bot•4mo ago

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erquhart•4mo ago

Welcome! Apart from the specific approach you’ve outlined, this is a pretty simple use case - you would determine if criteria is met at runtime in your Convex function. Here's a contrived mutation that depicts what I think you're going for:

const createAchievement = mutation({
  args: {
    achievementId: v.id("achievements"),
  },
  handler: async (ctx, args) => {
    const userId = await getAuthUserId(ctx);
    if (!userId) {
      throw new Error("User not found");
    }
    // Check for existing achievement
    const existingAchievement = await ctx.db
      .query("user_achievements")
      .withIndex("by_user_achievement", (q) =>
        q.eq("userId", userId).eq("achievementId", args.achievementId),
      )
      .first();
    if (existingAchievement) {
      return;
    }
    // Add logic here to determine if criteria is met
    // This includes running any necessary queries
    // If criteria is not met, return early

    // Create user achievement
    await ctx.db.insert("user_achievements", {
      userId,
      achievementId: args.achievementId,
    });
  },
});

const createAchievement = mutation({
  args: {
    achievementId: v.id("achievements"),
  },
  handler: async (ctx, args) => {
    const userId = await getAuthUserId(ctx);
    if (!userId) {
      throw new Error("User not found");
    }
    // Check for existing achievement
    const existingAchievement = await ctx.db
      .query("user_achievements")
      .withIndex("by_user_achievement", (q) =>
        q.eq("userId", userId).eq("achievementId", args.achievementId),
      )
      .first();
    if (existingAchievement) {
      return;
    }
    // Add logic here to determine if criteria is met
    // This includes running any necessary queries
    // If criteria is not met, return early

    // Create user achievement
    await ctx.db.insert("user_achievements", {
      userId,
      achievementId: args.achievementId,
    });
  },
});

Best practice to store "callbacks" in database?

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