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Method Signature

async save(): Promise<void>
Persists the current changes to the database. This instance method can be used to both create new models and update existing ones.
  • For new models (no ID): Generates a new ID, sets createdAt, and inserts into the database
  • For existing models (has ID): Updates updatedAt and saves changes to the database

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Parameters

None. This method operates on the current instance.

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Returns

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void
Promise<void>
Returns a promise that resolves when the save operation is complete. The model instance is updated with generated fields (id, timestamps).

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Examples

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Creating a New Model

const post = new BlogPost();

post.title = 'My Second Blog Post!';
post.content = 'This is the content.';
post.status = 'draft';

await post.save();

console.log(post.id); // Auto-generated ID
console.log(post.createdAt); // Timestamp when created

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Updating an Existing Model

// Retrieve existing model
const user = await User.find(userId);

if (user) {
  // Modify properties
  user.name = 'John Doe';
  user.email = 'john.doe@example.com';
  
  // Persist changes
  await user.save();
  
  console.log(user.updatedAt); // Timestamp of last update
}

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Building a Model Step by Step

const product = new Product();

// Set properties one by one
product.name = 'Wireless Keyboard';
product.price = 79.99;
product.category = 'electronics';
product.stock = 50;

// Save when ready
await product.save();

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Conditional Updates

const order = await Order.find(orderId);

if (order) {
  if (order.status === 'pending') {
    order.status = 'processing';
    order.processedAt = Date.now();
    await order.save();
  }
}

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Multiple Updates

const post = await BlogPost.find(postId);

if (post) {
  // First update
  post.title = 'Updated Title';
  await post.save();
  
  // Later, another update
  post.status = 'published';
  post.publishedAt = Date.now();
  await post.save();
}

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Timestamps

// New model
const newPost = new BlogPost();
newPost.title = 'New Post';
await newPost.save();

console.log(newPost.createdAt); // Set automatically
console.log(newPost.updatedAt); // null (not updated yet)

// Update existing model
newPost.title = 'Updated Post';
await newPost.save();

console.log(newPost.createdAt); // Original creation time
console.log(newPost.updatedAt); // Set to current time

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Error Handling

try {
  const user = new User();
  user.email = 'invalid-email'; // May fail validation
  user.name = 'Test User';
  
  await user.save();
} catch (error) {
  console.error('Failed to save user:', error);
}

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Comparison: save() vs create()

// Using create() - static method, one step
const post1 = await BlogPost.create({
  title: 'My Post',
  content: 'Content here'
});

// Using save() - instance method, more control
const post2 = new BlogPost();
post2.title = 'My Post';
post2.content = 'Content here';
// ... additional logic ...
await post2.save();

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When to Use Each

Use create() when:
  • You have all data ready at once
  • You want a single operation
  • You prefer a cleaner, declarative style
Use save() when:
  • You need to build the model step by step
  • You want to update existing models
  • You need conditional logic before saving
  • You’re working with instances from other operations