bknd-add-field

分类: 开发与编程 | 上传者: cameronapak | 下载: 0 | 版本: v1.0（最新）
Use when adding a field to an existing Bknd entity. Covers all field types (text, number, boolean, date, enum, json, jsonschema, media), field modifiers (.required(), .unique(), .default()), validation options, and UI vs code approaches.
更新日志: Source: GitHub https://github.com/cameronapak/freedom-stack-v3
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SKILL.md

---
name: bknd-add-field
description: Use when adding a field to an existing Bknd entity. Covers all field types (text, number, boolean, date, enum, json, jsonschema, media), field modifiers (.required(), .unique(), .default()), validation options, and UI vs code approaches.
---

# Add Field to Entity

Add a new field (column) to an existing entity in Bknd.

## Prerequisites

- Existing Bknd entity (see `bknd-create-entity`)
- For code mode: Access to your schema file

## When to Use UI vs Code

### Use UI Mode When
- Quick iteration/prototyping
- Non-developer adding fields
- Testing field configurations before coding

### Use Code Mode When
- Version control needed
- Reproducible schema changes
- Type safety required
- Team collaboration

## UI Approach

### Step 1: Access Entity

1. Start server: `npx bknd run`
2. Open `http://localhost:1337`
3. Navigate to **Data** section
4. Click on the target entity (e.g., `posts`)

### Step 2: Add Field

1. Click **+ Add Field**
2. Select field type from dropdown:
   - **Text**: Strings, emails, URLs
   - **Number**: Integers, decimals
   - **Boolean**: True/false
   - **Date**: Timestamps
   - **Enum**: Fixed set of values
   - **JSON**: Unstructured data
3. Enter field name (snake_case: `first_name`, `created_at`)

### Step 3: Configure Options

Based on field type, configure:

**All Types:**
- **Required**: Toggle on if field cannot be null
- **Default Value**: Set a default

**Text:**
- Min/Max Length
- Pattern (regex validation)

**Number:**
- Minimum/Maximum values
- Multiple Of (for integers)

**Enum:**
- Add enum values (one per line)

### Step 4: Save and Sync

1. Click **Save Field**
2. Click **Sync Database** to apply changes

## Code Approach

### Step 1: Locate Entity Definition

Find your entity in the schema:

```typescript
const schema = em({
  posts: entity("posts", {
    title: text().required(),
    // Add new fields here
  }),
});
```

### Step 2: Add Field

Add the new field to the entity's field object:

```typescript
const schema = em({
  posts: entity("posts", {
    title: text().required(),
    subtitle: text(),           // NEW: optional text field
    view_count: number(),       // NEW: optional number field
  }),
});
```

### Step 3: Restart Server

Bknd auto-syncs schema on startup. Restart your server to apply changes.

## Field Types Reference

### Text Field

```typescript
import { text } from "bknd";

entity("users", {
  // Basic optional text
  bio: text(),

  // Required text
  email: text().required(),

  // Unique constraint
  username: text().unique(),

  // With validation
  slug: text({
    minLength: 3,
    maxLength: 100,
    pattern: "^[a-z0-9-]+$",
  }).required(),

  // With default value
  status: text({ default_value: "active" }),
})
```

### Number Field

```typescript
import { number } from "bknd";

entity("products", {
  // Basic number
  quantity: number(),

  // Required with validation
  price: number({
    minimum: 0,
    maximum: 99999.99,
  }).required(),

  // Integer only (multipleOf: 1)
  rating: number({
    minimum: 1,
    maximum: 5,
    multipleOf: 1,
  }),
})
```

### Boolean Field

```typescript
import { boolean } from "bknd";

entity("posts", {
  // Defaults to false
  published: boolean(),

  // Default true
  active: boolean({ default_value: true }),
})
```

### Date Field

```typescript
import { date } from "bknd";

entity("events", {
  // Basic date
  start_date: date().required(),

  // Auto-set to current time
  created_at: date({ default_value: "now" }),
})
```

### Enum Field

**Note:** Import is `enumm` (double 'm') to avoid JS reserved word.

```typescript
import { enumm } from "bknd";

entity("posts", {
  // Array syntax
  status: enumm({
    enum: ["draft", "published", "archived"],
    default_value: "draft",
  }).required(),

  // Object syntax (key-value)
  priority: enumm({
    enum: {
      LOW: "low",
      MEDIUM: "medium",
      HIGH: "high",
    },
    default_value: "MEDIUM",
  }),
})
```

### JSON Field

```typescript
import { json } from "bknd";

entity("users", {
  // Untyped JSON
  metadata: json(),

  // Typed JSON (TypeScript only, no runtime validation)
  preferences: json<{
    theme: "light" | "dark";
    notifications: boolean;
  }>(),

  // With default
  tags: json<string[]>({ default_value: [] }),
})
```

### JSON Schema Field

For runtime-validated JSON:

```typescript
import { jsonschema } from "bknd";

entity("webhooks", {
  payload: jsonschema({
    type: "object",
    properties: {
      event: { type: "string" },
      timestamp: { type: "number" },
    },
    required: ["event", "timestamp"],
  }),
})
```

### Media Field

For file attachments:

```typescript
import { media } from "bknd";

entity("posts", {
  // Single file
  cover_image: media({ entity: "posts" }),

  // Multiple files with constraints
  gallery: media({
    entity: "posts",
    min_items: 1,
    max_items: 10,
    mime_types: ["image/jpeg", "image/png", "image/webp"],
  }),
})
```

## Field Modifiers

Chain modifiers after field type:

| Modifier | Description | Example |
|----------|-------------|---------|
| `.required()` | Cannot be null | `text().required()` |
| `.unique()` | Unique constraint | `text().unique()` |
| `.default(value)` | Default value | `text().default("pending")` |
| `.references(target)` | Foreign key | `number().references("users.id")` |

**Chaining example:**

```typescript
entity("users", {
  email: text().required().unique(),
  role: text().default("user"),
  org_id: number().references("organizations.id"),
})
```

## Field Naming Conventions

| Convention | Example | Notes |
|------------|---------|-------|
| snake_case | `first_name` | NOT `firstName` |
| Lowercase | `created_at` | NOT `CreatedAt` |
| Descriptive | `published_at` | NOT `pub` |

## Common Pitfalls

### Field Already Exists

**Error:** `Field "title" already exists on entity "posts"`

**Fix:** Each field name must be unique within an entity. Choose a different name.

### Invalid Field Name

**Error:** `Invalid field name`

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

```typescript
// Valid
title: text()
first_name: text()
item_2: text()

// Invalid
Title: text()        // No uppercase
2_item: text()       // Can't start with number
first-name: text()   // No hyphens
```

### Enum Import Mistake

**Error:** `enum is a reserved word`

**Fix:** Import and use `enumm` (double 'm'):

```typescript
// Wrong
import { enum } from "bknd";

// Correct
import { enumm } from "bknd";

status: enumm({ enum: ["a", "b"] })
```

### Missing Required Modifier on Existing Data

**Problem:** Adding `.required()` to field on entity with existing null values.

**Fix:** Either:
1. Update existing records to have non-null values first
2. Add a default value: `text({ default_value: "N/A" }).required()`
3. Keep field optional

### Field Changes Not Reflecting

**Problem:** Added field in code but not appearing.

**Fixes:**
1. Restart the server (schema syncs on startup)
2. Verify field is in the correct entity definition
3. Check for syntax errors in schema

## Verification

### UI Mode
1. Click on entity in Data section
2. Verify new field appears in field list
3. Create a test record with the new field

### Code Mode
```typescript
const api = app.getApi();

// Create record with new field
const result = await api.data.createOne("posts", {
  title: "Test",
  subtitle: "New field test",  // Your new field
});
console.log(result);
```

### CLI Check
```bash
npx bknd debug paths
# Check entity fields in output
```

## DOs and DON'Ts

**DO:**
- Use snake_case for field names
- Start with optional fields; make required later if needed
- Add default values for required fields on existing data
- Use appropriate field types (don't store numbers as text)

**DON'T:**
- Use `enum` import (use `enumm`)
- Add `.required()` to existing entities without defaults
- Use camelCase or PascalCase for field names
- Create redundant fields (e.g., `id` is auto-generated)

## Related Skills

- **bknd-create-entity** - Create a new entity first
- **bknd-define-relationship** - Add relationships between entities
- **bknd-modify-schema** - Rename or change field types
- **bknd-crud-create** - Insert data using new fields
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bknd-add-field

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