bknd-delete-entity（bknd 删除实体）

Delete Entity

Safely remove an entity (table) from Bknd, handling dependencies and avoiding data loss.

Prerequisites

• Existing Bknd app with entities (see bknd-create-entity)
• For code mode: Access to bknd.config.ts
• Critical: Backup database before deletion

Warning: Destructive Operation

Deleting an entity:

• Permanently removes the table and ALL its data
• Removes all relationships involving this entity
• May break application code referencing this entity
• Cannot be undone without database restore

When to Use UI vs Code

Use UI Mode When

• Quick prototype cleanup
• Development/testing environments
• Exploring what dependencies exist

Use Code Mode When

• Production changes
• Version control needed
• Team collaboration
• Reproducible deployments

Pre-Deletion Checklist

Before deleting an entity, verify:

1. Check for Relationships

Entities may be referenced by other entities via:

• Foreign keys (many-to-one)
• Junction tables (many-to-many)
• Self-references

2. Check for Data

const api = app.getApi();
const count = await api.data.count("entity_to_delete");
console.log(`Records to delete: ${count.data.count}`);

3. Check for Code References

Search codebase for:

• Entity name in queries: "entity_name"
• Type references: DB["entity_name"]
• API calls: api.data.*("entity_name")

4. Backup Data (If Needed)

// Export data before deletion
const api = app.getApi();
const allRecords = await api.data.readMany("entity_to_delete", {
  limit: 100000,
});

// Save to file
import { writeFileSync } from "fs";
writeFileSync(
  "backup-entity_to_delete.json",
  JSON.stringify(allRecords.data, null, 2)
);

Code Approach

Step 1: Identify Dependencies

Check your schema for relationships:

// Look for relationships involving this entity
const schema = em(
  {
    users: entity("users", { email: text().required() }),
    posts: entity("posts", { title: text().required() }),
    comments: entity("comments", { body: text() }),
  },
  ({ relation }, { users, posts, comments }) => {
    // posts depends on users (foreign key)
    relation(posts).manyToOne(users);
    // comments depends on posts (foreign key)
    relation(comments).manyToOne(posts);
  }
);

Dependency order matters: Delete children before parents.

Step 2: Remove Relationships First

If entity is a target of relationships, update schema to remove them:

// BEFORE: posts references users
const schema = em(
  {
    users: entity("users", { email: text().required() }),
    posts: entity("posts", { title: text().required() }),
  },
  ({ relation }, { users, posts }) => {
    relation(posts).manyToOne(users);
  }
);

// AFTER: Remove relationship before deleting users
const schema = em({
  users: entity("users", { email: text().required() }),
  posts: entity("posts", { title: text().required() }),
});

Step 3: Remove Entity from Schema

Simply remove the entity definition from your bknd.config.ts:

// BEFORE
const schema = em({
  users: entity("users", { email: text().required() }),
  posts: entity("posts", { title: text().required() }),
  deprecated_entity: entity("deprecated_entity", { data: text() }),
});

// AFTER - entity removed
const schema = em({
  users: entity("users", { email: text().required() }),
  posts: entity("posts", { title: text().required() }),
});

Step 4: Preview Changes

# See what will be dropped (dry run)
npx bknd sync

Output shows:

Tables to drop: deprecated_entity
Columns affected: (none on other tables)

Step 5: Apply Deletion

# Apply with drop flag (destructive)
npx bknd sync --drop

Or with force (enables all destructive operations):

npx bknd sync --force

Step 6: Clean Up Code

Remove all references:

• Delete type definitions
• Remove API calls
• Update imports

UI Approach

Step 1: Open Admin Panel

Navigate to http://localhost:1337 (or your configured URL).

Step 2: Go to Data Section

Click Data in the sidebar.

Step 3: Select Entity

Click on the entity you want to delete.

Step 4: Check Dependencies

Look for:

• Relations tab/section showing connected entities
• Warning messages about dependencies

Step 5: Export Data (Optional)

If you need the data:

1. Go to entity's data view
2. Export or manually copy records
3. Save backup externally

Step 6: Delete Entity

1. Open entity settings (gear icon or settings tab)
2. Look for Delete Entity or Remove button
3. Confirm deletion
4. Entity and all data removed

Step 7: Sync Database

After deletion, ensure database is synced:

• Click Sync Database if prompted
• Or run npx bknd sync --drop from CLI

Handling Dependencies

Scenario: Entity Has Child Records

Problem: Deleting users when posts has users_id foreign key.

Solution 1: Delete Children First

// 1. Delete all posts referencing users
const api = app.getApi();
await api.data.deleteMany("posts", {});

// 2. Then delete users
// (via schema removal + sync)

Solution 2: Remove Relationship First

// 1. Remove relationship from schema
// 2. Sync to remove foreign key
// 3. Remove entity from schema
// 4. Sync again with --drop

Scenario: Entity is Junction Table Target

Problem: tags is used in posts_tags junction table.

Solution:

// 1. Remove many-to-many relationship
const schema = em(
  {
    posts: entity("posts", { title: text() }),
    tags: entity("tags", { name: text() }),
  }
  // Remove: ({ relation }, { posts, tags }) => { relation(posts).manyToMany(tags); }
);

// 2. Sync to drop junction table
// npx bknd sync --drop

// 3. Remove tags entity
const schema = em({
  posts: entity("posts", { title: text() }),
});

// 4. Sync again to drop tags table
// npx bknd sync --drop

Scenario: Self-Referencing Entity

Problem: categories references itself (parent/children).

Solution:

// 1. Remove self-reference relation
const schema = em({
  categories: entity("categories", { name: text() }),
  // Remove self-referencing relation definition
});

// 2. Sync to remove foreign key
// npx bknd sync --drop

// 3. Remove entity
// (then sync again)

Deleting Multiple Entities

Order matters. Delete in dependency order (children first):

// Dependency tree:
// users <- posts <- comments
//       <- likes

// Delete order:
// 1. comments (depends on posts)
// 2. likes (depends on posts)
// 3. posts (depends on users)
// 4. users (no dependencies)

Batch Deletion Script

// scripts/cleanup-entities.ts
import { App } from "bknd";

async function cleanup() {
  const app = new App({
    connection: { url: process.env.DB_URL! },
  });
  await app.build();
  const api = app.getApi();

  // Delete in order
  const entitiesToDelete = ["comments", "likes", "posts"];

  for (const entity of entitiesToDelete) {
    const count = await api.data.count(entity);
    console.log(`Deleting ${count.data.count} records from ${entity}...`);
    await api.data.deleteMany(entity, {});
    console.log(`Deleted all records from ${entity}`);
  }

  console.log("Data cleanup complete. Now remove from schema and sync.");
}

cleanup().catch(console.error);

Common Pitfalls

Foreign Key Constraint Error

Error: Cannot drop table: foreign key constraint

Cause: Another entity references this one.

Fix: Remove relationship first, sync, then remove entity.

Junction Table Not Dropped

Problem: After removing many-to-many relation, junction table remains.

Fix: Run npx bknd sync --drop to include destructive operations.

Entity Still Appears in UI

Problem: Deleted from code but still shows in admin panel.

Fix:

• Ensure you ran npx bknd sync --drop
• Restart the Bknd server
• Clear browser cache

Application Crashes After Deletion

Problem: Code still references deleted entity.

Fix:

• Search codebase: grep -r "entity_name" src/
• Remove all API calls, types, imports
• Fix TypeScript errors

Accidentally Deleted Wrong Entity

Problem: Deleted production data.

Fix:

• If you have backup: Restore from backup
• If no backup: Data is permanently lost
• Prevention: Always backup before deletion

Verification

After Deletion

# 1. Check schema export (entity should be absent)
npx bknd schema --pretty | grep entity_name

# 2. Verify sync status
npx bknd sync
# Should show no pending changes

Via Code

const api = app.getApi();

// This should fail/return error for deleted entity
try {
  await api.data.readMany("deleted_entity", { limit: 1 });
  console.log("ERROR: Entity still exists!");
} catch (e) {
  console.log("Confirmed: Entity deleted successfully");
}

Via REST API

# Should return 404 or error
curl http://localhost:1337/api/data/deleted_entity

DOs and DON'Ts

DO:

• Backup data before deletion
• Check for dependencies first
• Delete children before parents
• Preview with npx bknd sync before --drop
• Remove code references after deletion
• Test in development before production

DON'T:

• Delete entities with active foreign keys
• Use --drop without previewing changes
• Delete in production without backup
• Assume UI deletion handles all cleanup
• Forget to remove TypeScript types/code references

Related Skills

• bknd-create-entity - Create new entities
• bknd-modify-schema - Modify existing schema
• bknd-define-relationship - Understand relationship dependencies
• bknd-crud-delete - Delete individual records (not tables)
• bknd-seed-data - Restore data from backup