convex-helpers

convex-helpers

A collection of useful code to complement the official packages.

Table of contents:

• Custom Functions
• Relationship helpers
• Action retry wrapper
• Stateful migrations
• Sessions
• Row-level security
• Zod validation
• Hono for HTTP endpoints
• CRUD
• Validator utilities
• Filter db queries with JS

Custom Functions

Build your own customized versions of query, mutation, and action that define custom behavior, allowing you to:

• Run authentication logic before the request starts.
• Look up commonly used data and add it to the ctx argument.
• Replace a ctx or argument field with a different value, such as a version of db that runs custom functions on data access.
• Consume arguments from the client that are not passed to the action, such as taking in an authentication parameter like an API key or session ID. These arguments must be sent up by the client along with each request.

See the associated Stack Post

For example:

import { customQuery } from "convex-helpers/server/customFunctions.js";

const myQueryBuilder = customQuery(query, {
  args: { apiToken: v.id("api_tokens") },
  input: async (ctx, args) => {
    const apiUser = await getApiUser(args.apiToken);
    const db = wrapDatabaseReader({ apiUser }, ctx.db, rlsRules);
    return { ctx: { db, apiUser }, args: {} };
  },
});

// Use the custom builder everywhere you would have used `query`
export const getSomeData = myQueryBuilder({
  args: { someArg: v.string() },
  handler: async (ctx, args) => {
    const { db, apiUser, scheduler } = ctx;
    const { someArg } = args;
    // ...
  },
});

Relationship helpers

Traverse database relationships without all the query boilerplate.

See the Stack post on relationship helpers and the relationship schema structures post.

Example:

import {
  getOneFromOrThrow,
  getManyFrom,
  getManyViaOrThrow,
} from "convex-helpers/server/relationships.js";
import { asyncMap } from "convex-helpers";

const author = await getOneFromOrThrow(db, "authors", "userId", user._id);
const posts = await asyncMap(
  // one-to-many
  await getManyFrom(db, "posts", "authorId", author._id),
  async (post) => {
    // one-to-many
    const comments = await getManyFrom(db, "comments", "postId", post._id);
    // many-to-many via join table
    const categories = await getManyViaOrThrow(
      db,
      "postCategories",
      "categoryId",
      "postId",
      post._id
    );
    return { ...post, comments, categories };
  }
);

Action retries

Use helper functions to retry a Convex action until it succeeds. An action should only be retried if it is safe to do so, i.e., if it's idempotent or doesn't have any unsafe side effects.

See the Stack post on retrying actions

Example:

 // in convex/utils.ts
 import { makeActionRetrier } from "convex-helpers/server/retries";

 export const { runWithRetries, retry } = makeActionRetrier("utils:retry");

 // in a mutation or action
 export const myMutation = mutation({
   args: {...},
   handler: async (ctx, args) => {
     //...
     await runWithRetries(ctx, internal.myModule.myAction, { arg1: 123 });
   }
 });

Stateful migrations

A helper to define and run migrations. You can persist the migration state to a table so you can query the status, or use it without persistence.

See the Stack post on migrations

In convex/schema.ts (if you want persistence):

// In convex/schema.ts
import { migrationsTable } from "convex-helpers/server/migrations";
export default defineSchema({
  migrations: migrationsTable,
  // other tables...
});

In convex/migrations.ts (or wherever you want to define them):

import { makeMigration } from "convex-helpers/server/migrations";
import { internalMutation } from "./_generated/server";

const migration = makeMigration(internalMutation, {
  migrationTable: "migrations",
});

export const myMigration = migration({
  table: "users",
  migrateOne: async (ctx, doc) => {
    await ctx.db.patch(doc._id, { newField: "value" });
  },
});

To run from the CLI / dashboard: You can run this manually from the CLI or dashboard:

# Start or resume a migration. No-ops if it's already done:
npx convex run migrations:myMigration '{fn: "migrations:myMigration"}'

Or call it directly within a function:

import { startMigration } from "convex-helpers/server/migrations";

//... within a mutation or action
await startMigration(ctx, internal.migrations.myMigration, {
  startCursor: null, // optional override
  batchSize: 10, // optional override
});

Or define many to run in series (skips already completed migrations / rows):

import { startMigrationsSerially } from "convex-helpers/server/migrations";
import { internalMutation } from "./_generated/server";

export default internalMutation(async (ctx) => {
  await startMigrationsSerially(ctx, [
    internal.migrations.myMigration,
    internal.migrations.myOtherMigration,
    //...
  ]);
});

If this default export is in convex/migrations.ts you can run:

npx convex run migrations --prod

Session tracking via client-side sessionID storage

Store a session ID on the client and pass it up with requests to keep track of a user, even if they aren't logged in.

Use the client-side helpers in react/sessions and server-side helpers in server/sessions.

See the associated Stack post for more information.

Example for a query (action & mutation are similar):

In your React's root, add the SessionProvider:

import { SessionProvider } from "convex-helpers/react/sessions";
//...
<ConvexProvider client={convex}>
  <SessionProvider>
    <App />
  </SessionProvider>
</ConvexProvider>;

Pass the session ID from the client automatically to a server query:

import { useSessionQuery } from "convex-helpers/react/sessions";

const results = useSessionQuery(api.myModule.mySessionQuery, { arg1: 1 });

Define a server query function in convex/myModule.ts:

export const mySessionQuery = queryWithSession({
  args: { arg1: v.number() },
  handler: async (ctx, args) => {
    // ctx.anonymousUser
  },
});

Using customQuery to make queryWithSession:

import { customQuery } from "convex-helpers/server/customFunctions";
import { SessionIdArg } from "convex-helpers/server/sessions";

export const queryWithSession = customQuery(query, {
  args: SessionIdArg,
  input: async (ctx, { sessionId }) => {
    const anonymousUser = await getAnonUser(ctx, sessionId);
    return { ctx: { ...ctx, anonymousUser }, args: {} };
  },
});

Note: getAnonUser is some function you write to look up a user by session.

Row-level security

See the Stack post on row-level security

Use the RowLevelSecurity helper to define withQueryRLS and withMutationRLS wrappers to add row-level checks for a server-side function. Any access to db inside functions wrapped with these will check your access rules on read/insert/modify per-document.

Zod Validation

Convex has argument validation, but if you prefer the Zod features for validating arguments, this is for you!

See the Stack post on Zod validation to see how to validate your Convex functions using the zod library.

Example:

import { z } from "zod";
import { zCustomQuery, zid } from "convex-helpers/server/zod";
import { NoOp } from "convex-helpers/server/customFunctions";

// Define this once - and customize like you would customQuery
const zodQuery = zCustomQuery(query, NoOp);

export const myComplexQuery = zodQuery({
  args: {
    userId: zid("users"),
    email: z.string().email(),
    num: z.number().min(0),
    nullableBigint: z.nullable(z.bigint()),
    boolWithDefault: z.boolean().default(true),
    null: z.null(),
    array: z.array(z.string()),
    optionalObject: z.object({ a: z.string(), b: z.number() }).optional(),
    union: z.union([z.string(), z.number()]),
    discriminatedUnion: z.discriminatedUnion("kind", [
      z.object({ kind: z.literal("a"), a: z.string() }),
      z.object({ kind: z.literal("b"), b: z.number() }),
    ]),
    literal: z.literal("hi"),
    enum: z.enum(["a", "b"]),
    readonly: z.object({ a: z.string(), b: z.number() }).readonly(),
    pipeline: z.number().pipe(z.coerce.string()),
  },
  handler: async (ctx, args) => {
    //... args at this point has been validated and has the types of what
    // zod parses the values into.
    // e.g. boolWithDefault is `bool` but has an input type `bool | undefined`.
  },
});

Hono for advanced HTTP endpoint definitions

Hono is an optimized web framework you can use to define HTTP api endpoints easily (httpAction in Convex).

See the guide on Stack for tips on using Hono for HTTP endpoints.

To use it, put this in your convex/http.ts file:

import { Hono } from "hono";
import { HonoWithConvex, HttpRouterWithHono } from "convex-helpers/server/hono";
import { ActionCtx } from "./_generated/server";

const app: HonoWithConvex<ActionCtx> = new Hono();

// See the [guide on Stack](https://stack.convex.dev/hono-with-convex)
// for tips on using Hono for HTTP endpoints.
app.get("/", async (c) => {
  return c.json("Hello world!");
});

export default new HttpRouterWithHono(app);

CRUD utilities

To generate a basic CRUD api for your tables, you can use this helper to define these functions for a given table:

• create
• read
• update
• delete
• paginate

Note: I recommend only doing this for prototyping or internal functions

Example:

// in convex/users.ts
import { crud } from "convex-helpers/server";
import { internalMutation, internalQuery } from "../convex/_generated/server";

const Users = Table("users", {...});

export const { read, update } = crud(Users, internalQuery, internalMutation);

// in convex/schema.ts
import { Users } from "./users";
export default defineSchema({users: Users.table});

// in some file, in an action:
const user = await ctx.runQuery(internal.users.read, { id: userId });

await ctx.runMutation(internal.users.update, { status: "inactive" });

Validator utilities

When using validators for defining database schema or function arguments, these validators help:

1. Add a Table utility that defines a table and keeps references to the fields to avoid re-defining validators. To learn more about sharing validators, read this article, an extension of this article.
2. Add utilties for partial, pick and omit to match the TypeScript type utilities.
3. Add shorthand for a union of literals, a nullable field, a deprecated field, and brandedString. To learn more about branded strings see this article.
4. Make the validators look more like TypeScript types, even though they're runtime values. (This is controvercial and not required to use the above).

Example:

import { Table } from "convex-helpers/server";
import {
  literals,
  partial,
  deprecated,
  brandedString,
} from "convex-helpers/validators";
import { omit, pick } from "convex-helpers";
import { Infer } from "convex/values";

// Define a validator that requires an Email string type.
export const emailValidator = brandedString("email");
// Define the Email type based on the branded string.
export type Email = Infer<typeof emailValidator>;

export const Account = Table("accounts", {
  balance: nullable(v.bigint()),
  status: literals("active", "inactive"),
  email: emailValidator,

  oldField: deprecated,
});

// convex/schema.ts
export default defineSchema({
  accounts: Account.table.index("status", ["status"]),
  //...
});

// some module
export const replaceUser = internalMutation({
  args: {
    id: Account._id,
    replace: object({
      // You can provide the document with or without system fields.
      ...Account.withoutSystemFields,
      ...partial(Account.systemFields),
    }),
  },
  handler: async (ctx, args) => {
    await ctx.db.replace(args.id, args.replace);
  },
});

// A validator just for balance & email: { balance: v.union(...), email: ..}
const balanceAndEmail = pick(Account.withoutSystemFields, ["balance", "email"]);

// A validator for all the fields except balance.
const accountWithoutBalance = omit(Account.withSystemFields, ["balance"]);

Filter

See the guide on Stack for an analysis of complex filters on Convex.

The filter helper composes with ctx.db.query to apply arbitrary TypeScript or JavaScript filters to a database query.

Examples:

import { filter } from "convex-helpers/server/filter";

export const evens = query({
  args: {},
  handler: async (ctx) => {
    return await filter(
      ctx.db.query("counter_table"),
      (c) => c.counter % 2 === 0
    ).collect();
  },
});

export const lastCountLongerThanName = query({
  args: {},
  handler: async (ctx) => {
    return await filter(
      ctx.db.query("counter_table"),
      (c) => c.counter > c.name.length
    )
      .order("desc")
      .first();
  },
});