Better Auth Convex

Local installation of Better Auth directly in your Convex app schema, with direct database access instead of component-based queries.

Why Better Auth Convex?

The official @convex-dev/better-auth component stores auth tables in a component schema. This package provides an alternative approach with direct schema integration.

This package provides direct local installation:

1. Auth tables live in your app schema - Not in a component boundary
2. Direct database access - No ctx.runQuery/ctx.runMutation overhead (>50ms latency that increases with app size)
3. Unified context - Auth triggers can directly access and modify your app tables transactionally
4. Full TypeScript inference - Single schema, single source of truth

[!WARNING] BREAKING CHANGE: Auth tables are stored in your app schema instead of the component schema. If you're already in production with @convex-dev/better-auth, you'll need to write a migration script to move your auth data.

Prerequisites

• Follow the official Better Auth + Convex setup guide first
• Choose your framework guide
  • IGNORE these steps from the framework guide:
    • Step 2: "Register the component" - We don't use the component approach
    • Step 5: convex/auth.ts - We'll use a different setup
    • Step 7: convex/http.ts - We use different route registration
• Then come back here to install locally

Installation

pnpm add [email protected] better-auth-convex

Local Setup

You'll need convex/auth.config.ts and update your files to install Better Auth directly in your app:

// convex/auth.ts
import { betterAuth } from 'better-auth';
import { convex } from '@convex-dev/better-auth/plugins';
import { admin, organization } from 'better-auth/plugins'; // Optional plugins
import {
  type AuthFunctions,
  createClient,
  createApi,
} from 'better-auth-convex';
import { internal } from './_generated/api';
import type { MutationCtx, QueryCtx, GenericCtx } from './_generated/server';
import type { DataModel } from './_generated/dataModel';
import schema from './schema'; // YOUR app schema with auth tables

// 1. Internal API functions for auth operations
const authFunctions: AuthFunctions = internal.auth;

// 2. Auth client with triggers that run in your app context
export const authClient = createClient<DataModel, typeof schema>({
  authFunctions,
  schema,
  triggers: {
    user: {
      beforeCreate: async (_ctx, data) => {
        // Ensure every user has a username, filling in a simple fallback
        const username =
          data.username?.trim() ||
          data.email?.split('@')[0] ||
          `user-${Date.now()}`;

        return {
          ...data,
          username,
        };
      },
      onCreate: async (ctx, user) => {
        // Direct access to your database
        // Example: Create personal organization
        const orgId = await ctx.db.insert('organization', {
          name: `${user.name}'s Workspace`,
          slug: `personal-${user._id}`,
          // ... other fields
        });

        // Update user with personalOrganizationId
        await ctx.db.patch(user._id, {
          personalOrganizationId: orgId,
        });
      },
      beforeDelete: async (ctx, user) => {
        // Example: clean up custom tables before removing the user
        if (user.personalOrganizationId) {
          await ctx.db.delete(user.personalOrganizationId);
        }

        return user;
      },
    },
    session: {
      onCreate: async (ctx, session) => {
        // Set default active organization on session creation
        if (!session.activeOrganizationId) {
          const user = await ctx.db.get(session.userId);

          if (user?.personalOrganizationId) {
            await ctx.db.patch(session._id, {
              activeOrganizationId: user.personalOrganizationId,
            });
          }
        }
      },
    },
  },
});

// 3. Create auth configuration (with options for HTTP-only mode)
export const createAuth = (
  ctx: GenericCtx,
  { optionsOnly } = { optionsOnly: false }
) => {
  const baseURL = process.env.NEXT_PUBLIC_SITE_URL!;

  return betterAuth({
    baseURL,
    logger: { disabled: optionsOnly },
    plugins: [
      convex(), // Required
      admin(),
      organization({
        // Organization plugin config
      }),
    ],
    session: {
      expiresIn: 60 * 60 * 24 * 30, // 30 days
      updateAge: 60 * 60 * 24 * 15, // 15 days
    },
    database: authClient.httpAdapter(ctx),
    // ... other config (social providers, user fields, etc.)
  });
};

// 4. Static auth instance for configuration
export const auth = createAuth({} as any, { optionsOnly: true });

// 5. IMPORTANT: Use getAuth for queries/mutations (direct DB access)
export const getAuth = <Ctx extends QueryCtx | MutationCtx>(ctx: Ctx) => {
  return betterAuth({
    ...auth.options,
    database: authClient.adapter(ctx, auth.options),
  });
};

// 6. Export trigger handlers for Convex
export const {
  beforeCreate,
  beforeDelete,
  beforeUpdate,
  onCreate,
  onDelete,
  onUpdate,
} = authClient.triggersApi();

// 7. Export API functions for internal use
export const {
  create,
  deleteMany,
  deleteOne,
  findMany,
  findOne,
  updateMany,
  updateOne,
} = createApi(schema, auth.options);

// Optional: If you need custom mutation builders (e.g., for custom context)
// Pass internalMutation to both createClient and createApi
// export const authClient = createClient<DataModel, typeof schema>({
//   authFunctions,
//   schema,
//   internalMutation: myCustomInternalMutation,
//   triggers: { ... }
// });
//
// export const { create, ... } = createApi(schema, {
//   ...auth.options,
//   internalMutation: myCustomInternalMutation,
// });

The trigger API exposes both before* and on* hooks. The before variants run inside the same Convex transaction just ahead of the database write, letting you normalize input, enforce invariants, or perform cleanup and return any transformed payload that should be persisted.

// convex/http.ts
import { httpRouter } from 'convex/server';
import { registerRoutes } from 'better-auth-convex';
import { createAuth } from './auth';

const http = httpRouter();

registerRoutes(http, createAuth);

export default http;

Key Concepts

Direct DB Access vs HTTP Adapter

// ✅ In queries/mutations: Use getAuth (direct DB access)
export const someQuery = query({
  handler: async (ctx) => {
    const auth = getAuth(ctx); // Direct DB access
    const user = await auth.api.getUser({ userId });
  },
});

// ⚠️ In actions: Use createAuth (needs HTTP adapter for external calls)
export const someAction = action({
  handler: async (ctx) => {
    const auth = createAuth(ctx); // Actions can't directly access DB
    // Use for webhooks, external API calls, etc.
  },
});

Unified Schema Benefits

// Component approach (@convex-dev/better-auth):
// - Auth tables in components.betterAuth schema
// - Requires ctx.runQuery/runMutation for auth operations
// - Component boundaries between auth and app tables

// Local approach (better-auth-convex):
// ✅ Auth tables in your app schema
// ✅ Direct queries across auth + app tables
// ✅ Single transaction for complex operations
// ✅ Direct function calls

Helper Functions

All helpers are exported from the main package:

import { getAuthUserId, getSession, getHeaders } from 'better-auth-convex';

// Get current user ID
const userId = await getAuthUserId(ctx);

// Get full session
const session = await getSession(ctx);

// Get headers for auth.api calls
const headers = await getHeaders(ctx);

Custom Mutation Builders

Both createClient and createApi accept an optional internalMutation parameter, allowing you to wrap internal mutations with custom context or behavior.

Use Cases

This is useful when you need to:

• Wrap database operations with custom context (e.g., triggers, logging)
• Apply middleware to all auth mutations
• Inject dependencies or configuration

Example with Triggers

import { customMutation, customCtx } from 'convex-helpers/server/customFunctions';
import { internalMutationGeneric } from 'convex/server';
import { registerTriggers } from '@convex/triggers';

const triggers = registerTriggers();

// Wrap mutations to include trigger-wrapped database
const internalMutation = customMutation(
  internalMutationGeneric,
  customCtx(async (ctx) => ({
    db: triggers.wrapDB(ctx).db,
  }))
);

// Pass to createClient
export const authClient = createClient<DataModel, typeof schema>({
  authFunctions,
  schema,
  internalMutation, // Use custom mutation builder
  triggers: { ... }
});

// Pass to createApi
export const { create, updateOne, ... } = createApi(schema, {
  ...auth.options,
  internalMutation, // Use same custom mutation builder
});

This ensures all auth operations (CRUD + triggers) use your wrapped database context.

Updating the Schema

Better Auth configuration changes may require schema updates. The Better Auth docs will often note when this is the case. To regenerate the schema (it's generally safe to do), run:

cd convex && npx @better-auth/cli generate -y --output authSchema.ts

Import Generated Schema (Recommended)

Import the generated schema in your convex/schema.ts:

import { authSchema } from './authSchema';
import { defineSchema } from 'convex/server';

export default defineSchema({
  ...authSchema,
  // Your other tables here
});

Or Use as Reference

Alternatively, use the generated schema as a reference to manually update your existing schema:

// Example: Adding a missing field discovered from generated schema
import { defineSchema, defineTable } from 'convex/server';
import { v } from 'convex/values';

export default defineSchema({
  user: defineTable({
    // ... existing fields
    twoFactorEnabled: v.optional(v.union(v.null(), v.boolean())), // New field from Better Auth update
    // ... rest of your schema
  }).index('email_name', ['email', 'name']),
  // ... other indexes
});

Adding Custom Indexes

Better Auth may log warnings about missing indexes for certain queries. You can add custom indexes by extending the generated schema:

// convex/schema.ts
import { authSchema } from './authSchema';
import { defineSchema } from 'convex/server';

export default defineSchema({
  ...authSchema,
  // Override with custom indexes
  user: authSchema.user.index('username', ['username']),
  // Your other tables
});

Note: authSchema table names and field names should not be customized directly. Use Better Auth configuration options to customize the schema, then regenerate to see the expected structure.

Credits

Built on top of Better Auth and @convex-dev/better-auth, optimized for Convex.