Convex Helpers

import { getOneFrom, getManyFrom } from "convex-helpers/server/relationships";

export const getTaskWithUser = query({
  args: { taskId: v.id("tasks") },
  handler: async (ctx, args) => {
    const task = await ctx.db.get(args.taskId);
    if (!task) return null;

    // Get related user
    const user = await getOneFrom(ctx.db, "users", "by_id", task.userId, "_id");

    // Get related comments
    const comments = await getManyFrom(
      ctx.db,
      "comments",
      "by_task",
      task._id,
      "taskId",
    );

    return { ...task, user, comments };
  },
});

Key Functions:

• getOneFrom - Get single related document
• getManyFrom - Get multiple related documents
• getManyVia - Get many-to-many relationships through junction table

2. Custom Functions (Data Protection) ⭐ MOST IMPORTANT

This is Convex's alternative to Row Level Security (RLS). Instead of database-level policies, use custom function wrappers to automatically add auth and access control to all queries and mutations.

Create wrapped versions of query/mutation/action with custom behavior.

Use when:

• Data protection and access control (PRIMARY USE CASE)
• Want to add auth logic to all functions
• Multi-tenant applications
• Role-based access control (RBAC)
• Need to inject common data into ctx
• Building internal-only functions
• Adding logging/monitoring to all functions

Why this instead of RLS:

• ✅ TypeScript, not SQL policies
• ✅ Full type safety
• ✅ Easy to test and debug
• ✅ More flexible than database policies
• ✅ Works across your entire backend

Example: Custom Query with Auto-Auth

// convex/lib/customFunctions.ts
import { customQuery } from "convex-helpers/server/customFunctions";
import { query } from "../_generated/server";

export const authenticatedQuery = customQuery(query, {
  args: {}, // No additional args required
  input: async (ctx, args) => {
    const identity = await ctx.auth.getUserIdentity();
    if (!identity) {
      throw new Error("Not authenticated");
    }

    const user = await ctx.db
      .query("users")
      .withIndex("by_token", (q) =>
        q.eq("tokenIdentifier", identity.tokenIdentifier),
      )
      .unique();

    if (!user) throw new Error("User not found");

    // Add user to context
    return { ctx: { ...ctx, user }, args };
  },
});

// Usage in your functions
export const getMyTasks = authenticatedQuery({
  handler: async (ctx) => {
    // ctx.user is automatically available!
    return await ctx.db
      .query("tasks")
      .withIndex("by_user", (q) => q.eq("userId", ctx.user._id))
      .collect();
  },
});

Example: Multi-Tenant Data Protection

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

// Organization-scoped query - automatic access control
export const orgQuery = customQuery(query, {
  args: { orgId: v.id("organizations") },
  input: async (ctx, args) => {
    const user = await getCurrentUser(ctx);

    // Verify user is a member of this organization
    const member = await ctx.db
      .query("organizationMembers")
      .withIndex("by_org_and_user", (q) =>
        q.eq("orgId", args.orgId).eq("userId", user._id),
      )
      .unique();

    if (!member) {
      throw new Error("Not authorized for this organization");
    }

    // Inject org context
    return {
      ctx: {
        ...ctx,
        user,
        orgId: args.orgId,
        role: member.role,
      },
      args,
    };
  },
});

// Usage - data automatically scoped to organization
export const getOrgProjects = orgQuery({
  args: { orgId: v.id("organizations") },
  handler: async (ctx) => {
    // ctx.user and ctx.orgId automatically available and verified!
    return await ctx.db
      .query("projects")
      .withIndex("by_org", (q) => q.eq("orgId", ctx.orgId))
      .collect();
  },
});

Example: Role-Based Access Control

import { customMutation } from "convex-helpers/server/customFunctions";
import { mutation } from "../_generated/server";

export const adminMutation = customMutation(mutation, {
  args: {},
  input: async (ctx, args) => {
    const user = await getCurrentUser(ctx);

    if (user.role !== "admin") {
      throw new Error("Admin access required");
    }

    return { ctx: { ...ctx, user }, args };
  },
});

// Usage - only admins can call this
export const deleteUser = adminMutation({
  args: { userId: v.id("users") },
  handler: async (ctx, args) => {
    // Only admins reach this code
    await ctx.db.delete(args.userId);
  },
});

3. Filter Helper

Apply complex TypeScript filters to database queries.

Use when:

• Need to filter by computed values
• Filtering logic is too complex for indexes
• Working with small result sets

Example:

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

export const getActiveTasks = query({
  handler: async (ctx) => {
    const now = Date.now();
    const threeDaysAgo = now - 3 * 24 * 60 * 60 * 1000;

    return await filter(
      ctx.db.query("tasks"),
      (task) =>
        !task.completed &&
        task.createdAt > threeDaysAgo &&
        task.priority === "high",
    ).collect();
  },
});

Note: Still prefer indexes when possible! Use filter for complex logic that can't be indexed.

4. Sessions

Track users across requests even when not logged in.

Use when:

• Need to track anonymous users
• Building shopping cart for guests
• Tracking user behavior before signup
• A/B testing without auth

Server setup — create a session-aware query builder:

// convex/lib/sessions.ts
import { customQuery } from "convex-helpers/server/customFunctions";
import { SessionIdArg } from "convex-helpers/server/sessions";
import { query } from "../_generated/server";

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

Usage in functions:

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

Client (React) — wrap app with SessionProvider:

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

// In your app root:
<ConvexProvider client={convex}>
  <SessionProvider>
    <App />
  </SessionProvider>
</ConvexProvider>

Client hooks:

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

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

5. Zod Validation

Use Zod schemas instead of Convex validators.

Use when:

• Already using Zod in your project
• Want more complex validation logic
• Need custom error messages

Example:

import { zCustomQuery } from "convex-helpers/server/zod";
import { z } from "zod";
import { query } from "./_generated/server";

const argsSchema = z.object({
  email: z.string().email(),
  age: z.number().min(18).max(120),
});

export const createUser = zCustomQuery(query, {
  args: argsSchema,
  handler: async (ctx, args) => {
    // args is typed from Zod schema
    return await ctx.db.insert("users", args);
  },
});

6. Alternative: Row-Level Security Helper

Note: Convex recommends using custom functions (see #2 above) as the primary data protection pattern. This RLS helper is an alternative approach that mimics traditional RLS by wrapping the database reader/writer.

Use when:

• Prefer RLS-style patterns from PostgreSQL
• Need to apply same rules across many functions
• Want centralized access control rules per table

However, custom functions are usually better because:

• More explicit (easy to see what auth is applied)
• Better error messages
• Easier to test

Example:

import {
  customCtx,
  customMutation,
  customQuery,
} from "convex-helpers/server/customFunctions";
import {
  Rules,
  RLSConfig,
  wrapDatabaseReader,
  wrapDatabaseWriter,
} from "convex-helpers/server/rowLevelSecurity";
import { DataModel } from "./_generated/dataModel";
import { mutation, query, QueryCtx } from "./_generated/server";

async function rlsRules(ctx: QueryCtx) {
  const identity = await ctx.auth.getUserIdentity();
  return {
    users: {
      read: async (_, user) => {
        if (!identity && user.age < 18) return false;
        return true;
      },
      insert: async (_, user) => {
        return true;
      },
      modify: async (_, user) => {
        if (!identity)
          throw new Error("Must be authenticated to modify a user");
        return user.tokenIdentifier === identity.tokenIdentifier;
      },
    },
  } satisfies Rules<QueryCtx, DataModel>;
}

// By default, tables with no rule have `defaultPolicy` set to "allow".
const config: RLSConfig = { defaultPolicy: "deny" };

const queryWithRLS = customQuery(
  query,
  customCtx(async (ctx) => ({
    db: wrapDatabaseReader(ctx, ctx.db, await rlsRules(ctx), config),
  })),
);

const mutationWithRLS = customMutation(
  mutation,
  customCtx(async (ctx) => ({
    db: wrapDatabaseWriter(ctx, ctx.db, await rlsRules(ctx), config),
  })),
);

Rules structure: Each table gets read, insert, and modify async functions that return boolean. The wrapDatabaseReader/wrapDatabaseWriter functions intercept all DB operations and enforce these rules transparently.

Recommended instead: Custom functions (see #2 above) — more explicit and type-safe.

7. Migrations

Run stateful online data migrations. This is a component (@convex-dev/migrations), not a convex-helpers function. See the convex-components skill for full details.

8. Triggers

Execute code automatically when data changes. Triggers run atomically within the same mutation — they intercept insert, patch, replace, and delete operations.

Use when:

• Maintaining computed/denormalized fields
• Cascading deletes
• Audit logging
• Data validation on writes
• Syncing with aggregate components

Setup — wrap mutations to enable triggers:

// convex/functions.ts
import {
  mutation as rawMutation,
  internalMutation as rawInternalMutation,
} from "./_generated/server";
import { DataModel } from "./_generated/dataModel";
import { Triggers } from "convex-helpers/server/triggers";
import {
  customCtx,
  customMutation,
} from "convex-helpers/server/customFunctions";

export const triggers = new Triggers<DataModel>();

export const mutation = customMutation(rawMutation, customCtx(triggers.wrapDB));
export const internalMutation = customMutation(
  rawInternalMutation,
  customCtx(triggers.wrapDB),
);

// IMPORTANT: Import trigger registrations AFTER exports
import "./triggers";

Register triggers — callback receives a change object:

// convex/triggers.ts
import { triggers } from "./functions";

triggers.register("tasks", async (ctx, change) => {
  // change.id — Document ID
  // change.operation — 'insert' | 'update' | 'delete'
  // change.newDoc — New document state (present on insert, update)
  // change.oldDoc — Old document state (present on update, delete)

  if (change.operation === "insert") {
    await ctx.db.insert("notifications", {
      userId: change.newDoc.userId,
      type: "task_created",
      taskId: change.id,
    });
  }
});

// Auto-sync aggregates
triggers.register("tasks", taskAggregate.trigger());

Critical: All mutation files must import from ./functions, NOT _generated/server, or triggers won't fire.

9. Aggregations

Efficient O(log n) count, sum, min, max operations. This is a component (@convex-dev/aggregate), not a convex-helpers function. See the convex-components skill for full details.

Keep aggregates in sync automatically using triggers (see #8 above):

triggers.register("tasks", tasksByStatus.trigger());

10. CRUD Generator

Auto-generate create, read, update, and delete functions for any table. Useful for internal tools, admin panels, and prototyping — but not recommended for production without access control wrappers around it.

Use when:

• Bootstrapping CRUD for a table quickly
• Building admin/internal APIs
• Prototyping before adding custom access control

Example:

// convex/users.ts
import { crud } from "convex-helpers/server/crud";
import schema from "./schema.js";

export const { create, read, update, destroy } = crud(schema, "users");

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

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

The generated functions are typed from your schema — create accepts the table's fields, update takes id + patch, read and destroy take id. For production, wrap these with custom functions (see #2) to add auth.

11. Validator Utilities

A rich set of utilities for building, composing, and validating Convex validators beyond the basic v.* primitives. These help you write stricter schemas, reuse validator fragments, and validate data at runtime.

Use when:

• Defining schemas with branded types, enums, or nullable fields
• Picking/omitting fields from a table's validator for args or return types
• Validating data at runtime (e.g., in actions before inserting)
• Deprecating old fields without breaking the schema

Schema-level utilities — import from convex-helpers/validators:

// convex/schema.ts
import {
  literals,
  deprecated,
  brandedString,
  nullable,
} from "convex-helpers/validators";
import { defineSchema, defineTable } from "convex/server";
import { v, Infer } from "convex/values";

export const emailValidator = brandedString("email");
export type Email = Infer<typeof emailValidator>;

export default defineSchema({
  accounts: defineTable({
    balance: nullable(v.bigint()), // v.union(v.bigint(), v.null())
    status: literals("active", "inactive"), // v.union(v.literal("active"), v.literal("inactive"))
    email: emailValidator, // typed string brand
    oldField: deprecated, // accepts any value, signals "stop using this"
  }).index("status", ["status"]),
});

Function-level utilities — typedV, doc, partial, pick, omit, validate:

import { doc, typedV, partial } from "convex-helpers/validators";
import { omit, pick } from "convex-helpers";
import schema from "./schema";

// Schema-aware validator builder — gives you vv.id("accounts"), vv.doc("accounts"), etc.
const vv = typedV(schema);

export const replaceUser = internalMutation({
  args: {
    id: vv.id("accounts"),
    replace: vv.object({
      ...schema.tables.accounts.validator.fields,
      ...partial(systemFields("accounts")),
    }),
  },
  returns: doc(schema, "accounts"),
  handler: async (ctx, args) => {
    await ctx.db.replace(args.id, args.replace);
    return await ctx.db.get(args.id);
  },
});

// Pick specific fields from a table's validator
const balanceAndEmail = pick(vv.doc("accounts").fields, ["balance", "email"]);

// Omit fields
const accountWithoutBalance = omit(vv.doc("accounts").fields, ["balance"]);

// Runtime validation — useful in actions before inserting
validate(balanceAndEmail, value); // returns boolean
validate(balanceAndEmail, value, { throw: true }); // throws ValidationError
validate(vv.id("accounts"), id, { db: ctx.db }); // validates ID exists in table

Key functions:

• brandedString(name) — typed string brand (e.g., emails, slugs)
• literals(...values) — union of string/number literals (enum-like)
• nullable(validator) — shorthand for v.union(validator, v.null())
• deprecated — marks a field as deprecated in schema
• partial(fields) — makes all fields optional
• typedV(schema) — schema-aware validator builder with .id(), .doc(), .object()
• doc(schema, table) — full document validator including system fields
• pick(fields, keys) / omit(fields, keys) — subset/exclude fields
• validate(validator, value, opts?) — runtime validation with optional throw

12. Cached Queries (React)

Drop-in replacement for Convex's useQuery that caches results client-side. When a component unmounts and remounts, it gets the cached value instantly instead of showing a loading state. Useful for tabs, navigation, and any UI where users revisit the same data.

Use when:

• Users navigate between views that re-fetch the same data
• You want instant UI on remount instead of loading spinners
• Tab-based UIs, sidebars, or detail panels

Setup — wrap your app with the cache provider:

import { ConvexQueryCacheProvider } from "convex-helpers/react/cache";
// For Next.js: import from "convex-helpers/react/cache/provider";

export default function App({ children }) {
  return (
    <ConvexClientProvider>
      <ConvexQueryCacheProvider>
        {children}
      </ConvexQueryCacheProvider>
    </ConvexClientProvider>
  );
}

Usage — swap your import:

// Before:
// import { useQuery } from "convex/react";

// After:
import { useQuery } from "convex-helpers/react/cache";
// For Next.js: import from "convex-helpers/react/cache/hooks";

const users = useQuery(api.users.list);

Also provides cached versions of useQueries and usePaginatedQuery from the same module. Default cache expiration is 5 minutes, max 250 idle entries.

13. useQueryWithStatus (React)

Richer alternative to the standard useQuery that returns explicit status fields instead of undefined for loading and throwing on errors. Makes it easier to build UIs with proper loading/error states without try-catch.

Use when:

• You want to distinguish "loading" from "no data" (standard useQuery returns undefined for both)
• You need error objects instead of thrown exceptions
• Building UIs with loading/error/success states

Setup — create the hook once:

// lib/hooks.ts
import { makeUseQueryWithStatus } from "convex-helpers/react";
import { useQueries } from "convex/react";

export const useQueryWithStatus = makeUseQueryWithStatus(useQueries);

Usage:

import { useQueryWithStatus } from "@/lib/hooks";

function TaskList() {
  const { status, data, error, isSuccess, isPending, isError } =
    useQueryWithStatus(api.tasks.list, { userId: "123" });

  if (isPending) return <Spinner />;
  if (isError) return <ErrorMessage error={error} />;
  return <TaskTable tasks={data} />;
}

Returns { status, data, error, isSuccess, isPending, isError } — similar to TanStack Query's API shape, so it feels familiar if you've used that.

Common Patterns

Pattern 1: Authenticated Queries with User Context

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

export const authedQuery = customQuery(query, {
  args: {},
  input: async (ctx, args) => {
    const user = await getCurrentUser(ctx);
    return { ctx: { ...ctx, user }, args };
  },
});

// Now all queries automatically have user in context
export const getMyData = authedQuery({
  handler: async (ctx) => {
    // ctx.user is typed and available!
    return await ctx.db
      .query("data")
      .withIndex("by_user", (q) => q.eq("userId", ctx.user._id))
      .collect();
  },
});

Pattern 2: Loading Related Data

import { getOneFrom, getManyFrom } from "convex-helpers/server/relationships";

export const getPostWithDetails = query({
  args: { postId: v.id("posts") },
  handler: async (ctx, args) => {
    const post = await ctx.db.get(args.postId);
    if (!post) return null;

    // Load author
    const author = await getOneFrom(
      ctx.db,
      "users",
      "by_id",
      post.authorId,
      "_id",
    );

    // Load comments
    const comments = await getManyFrom(
      ctx.db,
      "comments",
      "by_post",
      post._id,
      "postId",
    );

    // Load tags (many-to-many)
    const tagLinks = await getManyFrom(
      ctx.db,
      "postTags",
      "by_post",
      post._id,
      "postId",
    );

    const tags = await Promise.all(
      tagLinks.map((link) =>
        getOneFrom(ctx.db, "tags", "by_id", link.tagId, "_id"),
      ),
    );

    return { ...post, author, comments, tags };
  },
});

Pattern 3: Batch Operations with Error Handling

import { asyncMap } from "convex-helpers";

export const batchUpdateTasks = mutation({
  args: {
    taskIds: v.array(v.id("tasks")),
    status: v.string(),
  },
  handler: async (ctx, args) => {
    const results = await asyncMap(args.taskIds, async (taskId) => {
      try {
        const task = await ctx.db.get(taskId);
        if (task) {
          await ctx.db.patch(taskId, { status: args.status });
          return { success: true, taskId };
        }
        return { success: false, taskId, error: "Not found" };
      } catch (error) {
        return { success: false, taskId, error: error.message };
      }
    });

    return results;
  },
});

Best Practices

1. Start with convex-helpers

   • Don't reinvent common patterns
   • Use battle-tested utilities
   • Contribute back if you build something useful

2. Custom Functions for Auth

   • Create authedQuery, authedMutation, etc.
   • Inject user context automatically
   • Reduces boilerplate

3. Relationships Over Nesting

   • Use relationship helpers
   • Keep data normalized
   • Load related data as needed

4. Filter Sparingly

   • Prefer indexes when possible
   • Use filter for complex computed logic
   • Good for small result sets

5. Sessions for Anonymous Users

   • Track before signup
   • Migrate to user account later
   • Great for cart, preferences, etc.

Documentation

• convex-helpers GitHub
• convex-helpers on npm
• Relationship Helpers Guide

When to Use What