bknd-create-entity（bknd 创建实体）

Create Entity

Create a new entity (database table) in Bknd. Entities are the foundation of your data model.

Prerequisites

• Bknd project initialized (npx bknd create or existing project)
• For code mode: TypeScript project with bknd package installed

When to Use UI vs Code

Use UI Mode When

• Exploring/prototyping quickly
• Non-developer or visual learner
• Making one-off changes
• Testing schema ideas before committing to code

Use Code Mode When

• Version control needed
• Reproducible setups across environments
• Team collaboration
• CI/CD pipelines
• Type safety required

UI Approach

Step 1: Access Admin Panel

1. Start your Bknd server: npx bknd run
2. Open browser to http://localhost:1337 (default port)
3. Navigate to Data section in sidebar

Step 2: Create Entity

1. Click + Add Entity button
2. Enter entity name (use plural, lowercase: posts, users, comments)
3. Configure primary key format:

- Integer (default): Auto-incrementing ID - UUID: Universally unique identifier

1. Click Create

Step 3: Add Fields

After entity creation, you're taken to the field editor:

1. Click + Add Field
2. Select field type (text, number, boolean, date, enum, json)
3. Configure field options:

- Name: snake_case (e.g., first_name, created_at) - Required: Toggle if field cannot be null - Default Value: Optional default

1. Click Save Field
2. Repeat for additional fields

Step 4: Sync Schema

Click Sync Database to apply changes to the actual database.

Code Approach

Step 1: Import Dependencies

import { em, entity, text, number, boolean, date, enumm, json } from "bknd";

Step 2: Define Entity

Create your entity within em():

const schema = em({
  posts: entity("posts", {
    title: text().required(),
    content: text(),
    published: boolean({ default_value: false }),
    view_count: number({ default_value: 0 }),
  }),
});

Step 3: Configure Primary Key (Optional)

Default is auto-incrementing integer. For UUID:

const schema = em({
  posts: entity("posts", {
    title: text().required(),
  }, {
    primary_format: "uuid",
  }),
});

Step 4: Export Types

Enable type-safe queries:

const schema = em({
  posts: entity("posts", {
    title: text().required(),
    content: text(),
  }),
});

// Extract and declare types
type Database = (typeof schema)["DB"];
declare module "bknd" {
  interface DB extends Database {}
}

Step 5: Use in App Configuration

import { App } from "bknd";

const app = new App({
  data: schema,
  // ... other config
});

Full Example

import { App, em, entity, text, number, boolean, date } from "bknd";

const schema = em({
  users: entity("users", {
    email: text().required().unique(),
    name: text(),
    active: boolean({ default_value: true }),
  }),
  posts: entity("posts", {
    title: text().required(),
    content: text(),
    published: boolean({ default_value: false }),
    published_at: date(),
  }),
});

type Database = (typeof schema)["DB"];
declare module "bknd" {
  interface DB extends Database {}
}

const app = new App({
  data: schema,
});

export default app;

Entity Naming Conventions

Auto-Generated Fields

Every entity automatically includes:

Note: For created_at/updated_at, use the timestamps plugin or add manually:

entity("posts", {
  title: text().required(),
  created_at: date({ default_value: "now" }),
  updated_at: date(),
})

Common Pitfalls

Entity Already Exists

Error: Entity "posts" already defined

Fix: Each entity name must be unique within em(). Check for duplicates.

Invalid Entity Name

Error: Invalid entity name

Fix: Use lowercase letters, numbers, and underscores only. Must start with letter.

// ✅ Valid
entity("posts", { ... })
entity("user_profiles", { ... })
entity("blog_posts_2024", { ... })

// ❌ Invalid
entity("Posts", { ... })        // No uppercase
entity("2024_posts", { ... })   // Can't start with number
entity("post-items", { ... })   // No hyphens

Schema Not Syncing

Problem: Created entity in code but table doesn't exist in database.

Fix: Ensure you're using the schema in your App config:

const app = new App({
  data: schema,  // Must pass schema here
});

Then restart the server - Bknd auto-syncs on startup.

Missing Type Safety

Problem: api.data.readMany("posts",...) has no type hints.

Fix: Add type declaration:

type Database = (typeof schema)["DB"];
declare module "bknd" {
  interface DB extends Database {}
}

Verification

UI Mode

1. Check entity appears in Data section
2. Click entity to see fields
3. Try creating a test record

Code Mode

// After app starts, verify entity exists
const api = app.getApi();
const result = await api.data.readMany("posts");
console.log(result); // Should return { data: [] } for empty entity

CLI Check

npx bknd debug routes
# Should show /api/data/posts endpoints

DOs and DON'Ts

DO:

• Use plural, lowercase entity names
• Start with essential fields; add more later
• Add type declarations for type safety
• Use primary_format: "uuid" for distributed systems

DON'T:

• Use singular names (user instead of users)
• Use PascalCase or camelCase for entity names
• Create entities without at least one field
• Forget to sync database after UI changes

Related Skills

• bknd-add-field - Add fields to existing entity
• bknd-define-relationship - Connect entities with relationships
• bknd-modify-schema - Rename or change entity configuration
• bknd-delete-entity - Safely remove an entity