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

• 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.

• Choose the shape using the decision tree below and read the matching reference file.

• 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.

• 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

• Create the component structure with convex.config.ts, schema.ts, and function files.

• Implement functions using the component's own ./_generated/server imports, not the app's generated files.

• Wire the component into the app with app.use(...). If the app does not already have convex/convex.config.ts, create it.

• Call the component from the app through components.<name> using ctx.runQuery, ctx.runMutation, or ctx.runAction.

• If React clients, HTTP callers, or public APIs need access, create wrapper functions in the app instead of exposing component functions directly.

• Run npx convex dev and fix codegen, type, or boundary issues before finishing.

Choose the Shape

Ask the user, then pick one path:

Goal Shape Reference

Component for this app only Local references/local-components.md

Publish or share across apps Packaged references/packaged-components.md

User explicitly needs local + shared library code Hybrid references/hybrid-components.md

Not sure Default to local references/local-components.md

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", ["userId"]),
});

// 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", (q) => q.eq("userId", args.userId))
      .filter((q) => q.eq(q.field("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. ctx.auth is not available inside components.

• Keep environment access in the app. Component functions cannot read process.env.

• Pass parent app IDs across the boundary as strings. 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.

• Import query, mutation, and action from the component's own ./_generated/server.

• Do not expose component functions directly to clients. Create app wrappers when client access is needed.

• If the component defines HTTP handlers, mount the routes in the app's convex/http.ts.

• If the component needs pagination, use paginator from convex-helpers instead of built-in .paginate().

• Add args and returns validators to all public component functions.

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() }

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 });
  },
});

Validation

Try validation in this order:

• npx convex codegen --component-dir convex/components/<name>

• npx convex codegen

• 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

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