Updating documents in Express - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to update a document by its ID using Express and Mongoose.

Express

app.put('/items/:id', async (req, res) => {
  try {
    const updatedItem = await Item.findByIdAndUpdate(req.params.id, [1], { new: true });
    res.json(updatedItem);
  } catch (error) {
    res.status(500).send(error.message);
  }
});

Drag options to blanks, or click blank then click option'

Areq.params

Breq.headers

Creq.query

Dreq.body

Attempts:

3 left

💡 Hint

Common Mistakes

Using req.params instead of req.body for update data

Forgetting to set { new: true } to return the updated document

To update a document, you pass the new data from the request body to the update function.

2fill in blank

medium

Complete the code to update a document and handle the case when the document is not found.

Express

app.put('/users/:id', async (req, res) => {
  try {
    const user = await User.findByIdAndUpdate(req.params.id, req.body, { new: true });
    if (!user) {
      return res.status([1]).send('User not found');
    }
    res.json(user);
  } catch (error) {
    res.status(500).send(error.message);
  }
});

Drag options to blanks, or click blank then click option'

A500

B400

C404

D200

Attempts:

3 left

💡 Hint

Common Mistakes

Using 400 or 500 status codes instead of 404 for not found

Not returning after sending the 404 response

If the document is not found, the server should respond with a 404 Not Found status.

3fill in blank

hard

Fix the error in the code to update a document using Mongoose's updateOne method.

Express

app.patch('/posts/:id', async (req, res) => {
  try {
    const result = await Post.updateOne({ _id: [1] }, req.body);
    res.json(result);
  } catch (error) {
    res.status(500).send(error.message);
  }
});

Drag options to blanks, or click blank then click option'

Areq.body.id

Breq.params.id

Creq.query.id

Dreq.params.postId

Attempts:

3 left

💡 Hint

Common Mistakes

Using req.body.id which may not exist

Using a wrong parameter name like req.params.postId

The document ID is in req.params.id, so use it to find the document to update.

4fill in blank

hard

Fill both blanks to update a document and return the updated document using findOneAndUpdate.

Express

app.put('/products/:id', async (req, res) => {
  try {
    const product = await Product.findOneAndUpdate({ _id: [1] }, [2], { new: true });
    if (!product) {
      return res.status(404).send('Product not found');
    }
    res.json(product);
  } catch (error) {
    res.status(500).send(error.message);
  }
});

Drag options to blanks, or click blank then click option'

Areq.params.id

Breq.body

Creq.query

Dreq.params.productId

Attempts:

3 left

💡 Hint

Common Mistakes

Using req.query instead of req.body for update data

Using wrong parameter name for ID

Use req.params.id to find the product and req.body for the update data.

5fill in blank

hard

Fill all three blanks to update a document with validation and return the updated document.

Express

app.patch('/orders/:id', async (req, res) => {
  try {
    const order = await Order.findByIdAndUpdate([1], [2], { new: true, runValidators: [3] });
    if (!order) {
      return res.status(404).send('Order not found');
    }
    res.json(order);
  } catch (error) {
    res.status(400).send(error.message);
  }
});

Drag options to blanks, or click blank then click option'

Areq.params.id

Breq.body

Ctrue

Dfalse

Attempts:

3 left

💡 Hint

Common Mistakes

Not enabling runValidators, so invalid data can be saved

Using wrong parameter names for ID or update data

Use req.params.id to find the order, req.body for update data, and set runValidators to true to enforce schema validation.

Practice

1. What does the findByIdAndUpdate method do in Express with Mongoose?

easy

A. It updates a document by its ID and returns the updated document.

B. It deletes a document by its ID.

C. It creates a new document with a given ID.

D. It finds a document but does not update it.

Solution

1. Step 1: Understand the method purpose

   findByIdAndUpdate is used to find a document by its ID and update it with new data.

2. Step 2: Check the return value

   When used with { new: true }, it returns the updated document, not the old one.

3. Final Answer:

   It updates a document by its ID and returns the updated document. -> Option A

4. Quick Check:

   Update document by ID = A [OK]

Hint: Remember: findByIdAndUpdate updates and returns new data [OK]

Common Mistakes:

• Confusing update with delete operation
• Expecting it to create a new document
• Thinking it only finds without updating

2. Which of the following is the correct syntax to update a document by ID and return the updated document in Express with Mongoose?

easy

A. Model.findOneAndUpdate(id, update);

B. Model.updateById(id, update, callback);

C. Model.update(id, update, { returnNew: true });

D. Model.findByIdAndUpdate(id, update, { new: true }, callback);

Solution

1. Step 1: Identify correct method and parameters

   The correct method is findByIdAndUpdate with parameters: id, update object, options, and callback.

2. Step 2: Confirm option for returning updated document

   The option { new: true } ensures the updated document is returned.

3. Final Answer:

   Model.findByIdAndUpdate(id, update, { new: true }, callback); -> Option D

4. Quick Check:

   Correct syntax includes { new: true } = C [OK]

Hint: Use { new: true } option to get updated document [OK]

Common Mistakes:

• Using wrong method name like updateById
• Omitting the { new: true } option
• Passing incorrect parameters order

3. Given the code snippet:

Model.findByIdAndUpdate('123', { name: 'Alice' }, { new: true }, (err, doc) => {
  if (err) return console.error(err);
  console.log(doc.name);
});

What will be printed if the update is successful?

medium

A. The old name before update

B. Alice

C. undefined

D. An error message

Solution

1. Step 1: Understand the update and options

   The update changes the name to 'Alice' and { new: true } returns the updated document.

2. Step 2: Check the console output

   The callback logs doc.name, which will be 'Alice' after update.

3. Final Answer:

   Alice -> Option B

4. Quick Check:

   Updated document name logged = B [OK]

Hint: With { new: true }, console logs updated value [OK]

Common Mistakes:

• Expecting old value instead of updated
• Not using { new: true } option
• Misreading callback parameters

4. Identify the error in this code snippet for updating a document:

Model.findByIdAndUpdate('123', { age: 30 }, (err, doc) => {
  if (err) console.log(err);
  else console.log(doc);
});

medium

A. The update object should be a string

B. Using wrong method name, should be updateById

C. Missing the { new: true } option to get updated document

D. Callback function parameters are incorrect

Solution

1. Step 1: Check method usage

   The method findByIdAndUpdate is correct and callback parameters are valid.

2. Step 2: Identify missing option

   Without { new: true }, the returned document is the old one, not updated.

3. Final Answer:

   Missing the { new: true } option to get updated document -> Option C

4. Quick Check:

   Return updated doc requires { new: true } = D [OK]

Hint: Add { new: true } to get updated document in callback [OK]

Common Mistakes:

• Assuming updateById is a valid method
• Expecting updated doc without { new: true }
• Thinking update object must be string

5. You want to update a user's email only if the new email is not empty and valid. Which approach correctly updates the document safely in Express with Mongoose?

hard

A. Check email validity before calling findByIdAndUpdate, then update with { new: true } option.

B. Call findByIdAndUpdate directly without validation to save time.

C. Use findByIdAndUpdate with an empty update object if email is invalid.

D. Update the document without callback and ignore errors.

Solution

1. Step 1: Validate input before updating

   Always check if the new email is valid and not empty before updating to avoid bad data.

2. Step 2: Use findByIdAndUpdate with { new: true }

   Update the document with the valid email and use { new: true } to get the updated document.

3. Final Answer:

   Check email validity before calling findByIdAndUpdate, then update with { new: true } option. -> Option A

4. Quick Check:

   Validate input + update with new:true = A [OK]

Hint: Always validate input before updating documents [OK]

Common Mistakes:

• Skipping validation and risking bad data
• Updating with empty or invalid data
• Ignoring errors by not using callbacks