Convex Schema Validator

Convex Schema Validator

Define and validate database schemas in Convex with proper typing, index configuration, optional fields, unions, and strategies for schema migrations.

Documentation Sources

Before implementing, do not assume; fetch the latest documentation:

• Primary: https://docs.convex.dev/database/schemas
• Indexes: https://docs.convex.dev/database/indexes
• Data Types: https://docs.convex.dev/database/types
• For broader context: https://docs.convex.dev/llms.txt

Instructions

Basic Schema Definition

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

export default defineSchema({
  users: defineTable({
    name: v.string(),
    email: v.string(),
    avatarUrl: v.optional(v.string()),
    createdAt: v.number(),
  }),
  
  tasks: defineTable({
    title: v.string(),
    description: v.optional(v.string()),
    completed: v.boolean(),
    userId: v.id("users"),
    priority: v.union(
      v.literal("low"),
      v.literal("medium"),
      v.literal("high")
    ),
  }),
});

Validator Types

Index Configuration

export default defineSchema({
  messages: defineTable({
    channelId: v.id("channels"),
    authorId: v.id("users"),
    content: v.string(),
    sentAt: v.number(),
  })
    // Single field index
    .index("by_channel", ["channelId"])
    // Compound index
    .index("by_channel_and_author", ["channelId", "authorId"])
    // Index for sorting
    .index("by_channel_and_time", ["channelId", "sentAt"]),
    
  // Full-text search index
  articles: defineTable({
    title: v.string(),
    body: v.string(),
    category: v.string(),
  })
    .searchIndex("search_content", {
      searchField: "body",
      filterFields: ["category"],
    }),
});

Complex Types

export default defineSchema({
  // Nested objects
  profiles: defineTable({
    userId: v.id("users"),
    settings: v.object({
      theme: v.union(v.literal("light"), v.literal("dark")),
      notifications: v.object({
        email: v.boolean(),
        push: v.boolean(),
      }),
    }),
  }),

  // Arrays of objects
  orders: defineTable({
    customerId: v.id("users"),
    items: v.array(v.object({
      productId: v.id("products"),
      quantity: v.number(),
      price: v.number(),
    })),
    status: v.union(
      v.literal("pending"),
      v.literal("processing"),
      v.literal("shipped"),
      v.literal("delivered")
    ),
  }),

  // Record type for dynamic keys
  analytics: defineTable({
    date: v.string(),
    metrics: v.record(v.string(), v.number()),
  }),
});

Discriminated Unions

export default defineSchema({
  events: defineTable(
    v.union(
      v.object({
        type: v.literal("user_signup"),
        userId: v.id("users"),
        email: v.string(),
      }),
      v.object({
        type: v.literal("purchase"),
        userId: v.id("users"),
        orderId: v.id("orders"),
        amount: v.number(),
      }),
      v.object({
        type: v.literal("page_view"),
        sessionId: v.string(),
        path: v.string(),
      })
    )
  ).index("by_type", ["type"]),
});

Optional vs Nullable Fields

export default defineSchema({
  items: defineTable({
    // Optional: field may not exist
    description: v.optional(v.string()),
    
    // Nullable: field exists but can be null
    deletedAt: v.union(v.number(), v.null()),
    
    // Optional and nullable
    notes: v.optional(v.union(v.string(), v.null())),
  }),
});

Index Naming Convention

Always include all indexed fields in the index name:

export default defineSchema({
  posts: defineTable({
    authorId: v.id("users"),
    categoryId: v.id("categories"),
    publishedAt: v.number(),
    status: v.string(),
  })
    // Good: descriptive names
    .index("by_author", ["authorId"])
    .index("by_author_and_category", ["authorId", "categoryId"])
    .index("by_category_and_status", ["categoryId", "status"])
    .index("by_status_and_published", ["status", "publishedAt"]),
});

Schema Migration Strategies

Adding New Fields

// Before
users: defineTable({
  name: v.string(),
  email: v.string(),
})

// After - add as optional first
users: defineTable({
  name: v.string(),
  email: v.string(),
  avatarUrl: v.optional(v.string()), // New optional field
})

Backfilling Data

// convex/migrations.ts
import { internalMutation } from "./_generated/server";
import { v } from "convex/values";

export const backfillAvatars = internalMutation({
  args: {},
  returns: v.number(),
  handler: async (ctx) => {
    const users = await ctx.db
      .query("users")
      .filter((q) => q.eq(q.field("avatarUrl"), undefined))
      .take(100);

    for (const user of users) {
      await ctx.db.patch(user._id, {
        avatarUrl: `https://api.dicebear.com/7.x/initials/svg?seed=${user.name}`,
      });
    }

    return users.length;
  },
});

Making Optional Fields Required

// Step 1: Backfill all null values
// Step 2: Update schema to required
users: defineTable({
  name: v.string(),
  email: v.string(),
  avatarUrl: v.string(), // Now required after backfill
})

Examples

Complete E-commerce Schema

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

export default defineSchema({
  users: defineTable({
    email: v.string(),
    name: v.string(),
    role: v.union(v.literal("customer"), v.literal("admin")),
    createdAt: v.number(),
  })
    .index("by_email", ["email"])
    .index("by_role", ["role"]),

  products: defineTable({
    name: v.string(),
    description: v.string(),
    price: v.number(),
    category: v.string(),
    inventory: v.number(),
    isActive: v.boolean(),
  })
    .index("by_category", ["category"])
    .index("by_active_and_category", ["isActive", "category"])
    .searchIndex("search_products", {
      searchField: "name",
      filterFields: ["category", "isActive"],
    }),

  orders: defineTable({
    userId: v.id("users"),
    items: v.array(v.object({
      productId: v.id("products"),
      quantity: v.number(),
      priceAtPurchase: v.number(),
    })),
    total: v.number(),
    status: v.union(
      v.literal("pending"),
      v.literal("paid"),
      v.literal("shipped"),
      v.literal("delivered"),
      v.literal("cancelled")
    ),
    shippingAddress: v.object({
      street: v.string(),
      city: v.string(),
      state: v.string(),
      zip: v.string(),
      country: v.string(),
    }),
    createdAt: v.number(),
    updatedAt: v.number(),
  })
    .index("by_user", ["userId"])
    .index("by_user_and_status", ["userId", "status"])
    .index("by_status", ["status"]),

  reviews: defineTable({
    productId: v.id("products"),
    userId: v.id("users"),
    rating: v.number(),
    comment: v.optional(v.string()),
    createdAt: v.number(),
  })
    .index("by_product", ["productId"])
    .index("by_user", ["userId"]),
});

Using Schema Types in Functions

// convex/products.ts
import { query, mutation } from "./_generated/server";