Convex Create Component

Convex Create Component

Create reusable Convex components with clear boundaries and a small app-facing API.

When to Use

• Creating a new Convex component in an existing app
• Extracting reusable backend logic into a component
• Building a third-party integration that should own its own tables and

workflows

• Packaging Convex functionality for reuse across multiple apps

When Not to Use

• One-off business logic that belongs in the main app
• Thin utilities that do not need Convex tables or functions
• App-level orchestration that should stay in convex/
• Cases where a normal TypeScript library is enough

Workflow

1. Ask the user what they are building and what the end goal is. If the repo already makes the answer obvious, say so and confirm before proceeding. 2. Choose the shape using the decision tree below and read the matching reference file. 3. Decide whether a component is justified. Prefer normal app code or a regular library if the feature does not need isolated tables, backend functions, or reusable persistent state. 4. Make a short plan for:

• what tables the component owns
• what public functions it exposes
• what data must be passed in from the app (auth, env vars, parent IDs)
• what stays in the app as wrappers or HTTP mounts

5. Create the component structure with convex.config.ts, schema.ts, and function files. 6. Implement functions using the component's own ./_generated/server imports, not the app's generated files. 7. Wire the component into the app with app.use(...). If the app does not already have convex/convex.config.ts, create it. 8. Call the component from the app through components.<name> using ctx.runQuery, ctx.runMutation, or ctx.runAction. 9. If React clients, HTTP callers, or public APIs need access, create wrapper functions in the app instead of exposing component functions directly. 10. Run npx convex dev and fix codegen, type, or boundary issues before finishing.

Choose the Shape

Ask the user, then pick one path:

Read exactly one reference file before proceeding.

Default Approach

Unless the user explicitly wants an npm package, default to a local component:

• Put it under convex/components/<componentName>/
• Define it with defineComponent(...) in its own convex.config.ts
• Install it from the app's convex/convex.config.ts with app.use(...)
• Let npx convex dev generate the component's own _generated/ files

Component Skeleton

A minimal local component with a table and two functions, plus the app wiring.

// convex/components/notifications/convex.config.ts
import { defineComponent } from "convex/server";

export default defineComponent("notifications");

// convex/components/notifications/schema.ts
import { defineSchema, defineTable } from "convex/server";
import { v } from "convex/values";

export default defineSchema({
  notifications: defineTable({
    userId: v.string(),
    message: v.string(),
    read: v.boolean(),
  }).index("by_user_read", ["userId", "read"]),
});

// convex/components/notifications/lib.ts
import { v } from "convex/values";
import { mutation, query } from "./_generated/server.js";

export const send = mutation({
  args: { userId: v.string(), message: v.string() },
  returns: v.id("notifications"),
  handler: async (ctx, args) => {
    return await ctx.db.insert("notifications", {
      userId: args.userId,
      message: args.message,
      read: false,
    });
  },
});

export const listUnread = query({
  args: { userId: v.string() },
  returns: v.array(
    v.object({
      _id: v.id("notifications"),
      _creationTime: v.number(),
      userId: v.string(),
      message: v.string(),
      read: v.boolean(),
    }),
  ),
  handler: async (ctx, args) => {
    return await ctx.db
      .query("notifications")
      .withIndex("by_user_read", (q) =>
        q.eq("userId", args.userId).eq("read", false),
      )
      .collect();
  },
});

// convex/convex.config.ts
import { defineApp } from "convex/server";
import notifications from "./components/notifications/convex.config.js";

const app = defineApp();
app.use(notifications);

export default app;

// convex/notifications.ts  (app-side wrapper)
import { v } from "convex/values";
import { mutation, query } from "./_generated/server";
import { components } from "./_generated/api";
import { getAuthUserId } from "@convex-dev/auth/server";

export const sendNotification = mutation({
  args: { message: v.string() },
  returns: v.null(),
  handler: async (ctx, args) => {
    const userId = await getAuthUserId(ctx);
    if (!userId) throw new Error("Not authenticated");

    await ctx.runMutation(components.notifications.lib.send, {
      userId,
      message: args.message,
    });
    return null;
  },
});

export const myUnread = query({
  args: {},
  handler: async (ctx) => {
    const userId = await getAuthUserId(ctx);
    if (!userId) throw new Error("Not authenticated");

    return await ctx.runQuery(components.notifications.lib.listUnread, {
      userId,
    });
  },
});

Note the reference path shape: a function in convex/components/notifications/lib.ts is called as components.notifications.lib.send from the app.

Critical Rules

• Keep authentication in the app, because ctx.auth is not available inside

components.

• Keep environment access in the app, because component functions cannot read

process.env.

• Pass parent app IDs across the boundary as strings, because Id types become

plain strings in the app-facing ComponentApi.

• Do not use v.id("parentTable") for app-owned tables inside component args or

schema, because the component has no access to the app's table namespace.

• Import query, mutation, and action from the component's own

./_generated/server, not the app's generated files.

• Do not expose component functions directly to clients. Create app wrappers

when client access is needed, because components are internal and need auth/env wiring the app provides.

• If the component defines HTTP handlers, mount the routes in the app's

convex/http.ts, because components cannot register their own HTTP routes.

• If the component needs pagination, use paginator from convex-helpers

instead of built-in .paginate(), because .paginate() does not work across the component boundary.

• Define indexes for queried fields instead of using Convex .filter() after a

database query.

• Add args and returns validators to all public component functions, because

the component boundary requires explicit type contracts.

Patterns

Authentication and environment access

// Bad: component code cannot rely on app auth or env
const identity = await ctx.auth.getUserIdentity();
const apiKey = process.env.OPENAI_API_KEY;

// Good: the app resolves auth and env, then passes explicit values
const userId = await getAuthUserId(ctx);
if (!userId) throw new Error("Not authenticated");

await ctx.runAction(components.translator.translate, {
  userId,
  apiKey: process.env.OPENAI_API_KEY,
  text: args.text,
});

Client-facing API

// Bad: assuming a component function is directly callable by clients
export const send = components.notifications.send;

// Good: re-export through an app mutation or query
export const sendNotification = mutation({
  args: { message: v.string() },
  returns: v.null(),
  handler: async (ctx, args) => {
    const userId = await getAuthUserId(ctx);
    if (!userId) throw new Error("Not authenticated");

    await ctx.runMutation(components.notifications.lib.send, {
      userId,
      message: args.message,
    });
    return null;
  },
});

IDs across the boundary

// Bad: parent app table IDs are not valid component validators
args: {
  userId: v.id("users"),
}

// Good: treat parent-owned IDs as strings at the boundary
args: {
  userId: v.string(),
}

Advanced Patterns

For additional patterns including function handles for callbacks, deriving validators from schema, static configuration with a globals table, and class-based client wrappers, see references/advanced-patterns.md.

Validation

Try validation in this order:

1. npx convex codegen --component-dir convex/components/<name> 2. npx convex codegen 3. npx convex dev

Important:

• Fresh repos may fail these commands until CONVEX_DEPLOYMENT is configured.
• Until codegen runs, component-local ./_generated/* imports and app-side

components.<name>... references will not typecheck.

• If validation blocks on Convex login or deployment setup, stop and ask the

user for that exact step instead of guessing.

Reference Files

Read exactly one of these after the user confirms the goal:

• references/local-components.md
• references/packaged-components.md
• references/hybrid-components.md

Official docs: Authoring Components

Checklist

• [ ] Asked the user what they want to build and confirmed the shape
• [ ] Read the matching reference file
• [ ] Confirmed a component is the right abstraction
• [ ] Planned tables, public API, boundaries, and app wrappers
• [ ] Component lives under convex/components/<name>/ (or package layout if

publishing)

• [ ] Component imports from its own ./_generated/server
• [ ] Auth, env access, and HTTP routes stay in the app
• [ ] Parent app IDs cross the boundary as v.string()
• [ ] Public functions have args and returns validators
• [ ] Ran npx convex dev and fixed codegen or type issues

Advanced Component Patterns

Additional patterns for Convex components that go beyond the basics covered in the main skill file.

Function Handles for callbacks

When the app needs to pass a callback function to the component, use function handles. This is common for components that run app-defined logic on a schedule or in a workflow.

// App side: create a handle and pass it to the component
import { createFunctionHandle } from "convex/server";

export const startJob = mutation({
  handler: async (ctx) => {
    const handle = await createFunctionHandle(internal.myModule.processItem);
    await ctx.runMutation(components.workpool.enqueue, {
      callback: handle,
    });
  },
});

// Component side: accept and invoke the handle
import { v } from "convex/values";
import type { FunctionHandle } from "convex/server";
import { mutation } from "./_generated/server.js";

export const enqueue = mutation({
  args: { callback: v.string() },
  handler: async (ctx, args) => {
    const handle = args.callback as FunctionHandle<"mutation">;
    await ctx.scheduler.runAfter(0, handle, {});
  },
});

Deriving validators from schema

Instead of manually repeating field types in return validators, extend the schema validator:

import { v } from "convex/values";
import schema from "./schema.js";

const notificationDoc = schema.tables.notifications.validator.extend({
  _id: v.id("notifications"),
  _creationTime: v.number(),
});

export const getLatest = query({
  args: {},
  returns: v.nullable(notificationDoc),
  handler: async (ctx) => {
    return await ctx.db.query("notifications").order("desc").first();
  },
});

Static configuration with a globals table

A common pattern for component configuration is a single-document "globals" table:

// schema.ts
export default defineSchema({
  globals: defineTable({
    maxRetries: v.number(),
    webhookUrl: v.optional(v.string()),
  }),
  // ... other tables
});

// lib.ts
export const configure = mutation({
  args: { maxRetries: v.number(), webhookUrl: v.optional(v.string()) },
  returns: v.null(),
  handler: async (ctx, args) => {
    const existing = await ctx.db.query("globals").first();
    if (existing) {
      await ctx.db.patch(existing._id, args);
    } else {
      await ctx.db.insert("globals", args);
    }
    return null;
  },
});

Class-based client wrappers

For components with many functions or configuration options, a class-based client provides a cleaner API. This pattern is common in published components.

// src/client/index.ts
import type { GenericMutationCtx, GenericDataModel } from "convex/server";
import type { ComponentApi } from "../component/_generated/component.js";

type MutationCtx = Pick<GenericMutationCtx<GenericDataModel>, "runMutation">;

export class Notifications {
  constructor(
    private component: ComponentApi,
    private options?: { defaultChannel?: string },
  ) {}

  async send(ctx: MutationCtx, args: { userId: string; message: string }) {
    return await ctx.runMutation(this.component.lib.send, {
      ...args,
      channel: this.options?.defaultChannel ?? "default",
    });
  }
}

// App usage
import { Notifications } from "@convex-dev/notifications";
import { components } from "./_generated/api";

const notifications = new Notifications(components.notifications, {
  defaultChannel: "alerts",
});

export const send = mutation({
  args: { message: v.string() },
  handler: async (ctx, args) => {
    const userId = await getAuthUserId(ctx);
    await notifications.send(ctx, { userId, message: args.message });
  },
});

Hybrid Convex Components

Read this file only when the user explicitly wants a hybrid setup.

What This Means

A hybrid component combines a local Convex component with shared library code.

This can help when:

• the user wants a local install but also shared package logic
• the component needs extension points or override hooks
• some logic should live in normal TypeScript code outside the component

boundary

Default Advice

Treat hybrid as an advanced option, not the default.

Before choosing it, ask:

• Why is a plain local component not enough?
• Why is a packaged component not enough?
• What exactly needs to stay overridable or shared?

If the answer is vague, fall back to local or packaged.

Risks

• More moving parts
• Harder upgrades and backwards compatibility
• Easier to blur the component boundary

Checklist

• [ ] User explicitly needs hybrid behavior
• [ ] Local-only and packaged-only options were considered first
• [ ] The extension points are clearly defined before coding

Local Convex Components

Read this file when the component should live inside the current app and does not need to be published as an npm package.

When to Choose This

• The user wants the simplest path
• The component only needs to work in this repo
• The goal is extracting app logic into a cleaner boundary

Default Layout

Use this structure unless the repo already has a clear alternative pattern:

convex/
  convex.config.ts
  components/
    <name>/
      convex.config.ts
      schema.ts
      <feature>.ts

Workflow Notes

• Define the component with defineComponent("<name>")
• Install it from the app with defineApp() and app.use(...)
• Keep auth, env access, public API wrappers, and HTTP route mounting in the app
• Let the component own isolated tables and reusable backend workflows
• Add app wrappers if clients need to call into the component

Checklist

• [ ] Component is inside convex/components/<name>/
• [ ] App installs it with app.use(...)
• [ ] Component owns only its own tables
• [ ] App wrappers handle client-facing calls when needed

Packaged Convex Components

Read this file when the user wants a reusable npm package or a component shared across multiple apps.

When to Choose This

• The user wants to publish the component
• The user wants a stable reusable package boundary
• The component will be shared across multiple apps or teams

Default Approach

• Prefer starting from npx create-convex@latest --component when possible
• Keep the official authoring docs as the source of truth for package layout and

exports

• Validate the bundled package through an example app, not just the source files

Build Flow

When building a packaged component, make sure the bundled output exists before the example app tries to consume it.

Recommended order:

1. npx convex codegen --component-dir ./path/to/component 2. Run the package build command 3. Run npx convex dev --typecheck-components in the example app

Do not assume normal app codegen is enough for packaged component workflows.

Package Exports

If publishing to npm, make sure the package exposes the entry points apps need:

• package root for client helpers, types, or classes
• ./convex.config.js for installing the component
• ./_generated/component.js for the app-facing ComponentApi type
• ./test for testing helpers when applicable

Testing

• Use convex-test for component logic
• Register the component schema and modules with the test instance
• Test app-side wrapper code from an example app that installs the package
• Export a small helper from ./test if consumers need easy test registration

Checklist

• [ ] Packaging is actually required
• [ ] Build order avoids bundle and codegen races
• [ ] Package exports include install and typing entry points
• [ ] Example app exercises the packaged component
• [ ] Core behavior is covered by tests