Pagination pattern with skip and limit in MongoDB - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to skip the first 10 documents in the collection.

MongoDB

db.collection.find().[1](10)

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

Acount

Blimit

Cskip

Dsort

Attempts:

3 left

💡 Hint

Common Mistakes

Using limit instead of skip will restrict the number of documents returned, not skip them.

Using sort or count does not skip documents.

The skip(10) method skips the first 10 documents, useful for pagination.

2fill in blank

medium

Complete the code to limit the result to 5 documents after skipping.

MongoDB

db.collection.find().skip(10).[1](5)

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

Alimit

Bsort

Ccount

Daggregate

Attempts:

3 left

💡 Hint

Common Mistakes

Using sort or count instead of limit will not restrict the number of documents returned.

Using aggregate is for pipeline operations, not simple limiting.

The limit(5) method restricts the number of documents returned to 5, useful for pagination.

3fill in blank

hard

Fix the error in the code to correctly paginate by skipping 20 and limiting to 10 documents.

MongoDB

db.collection.find().[1](10).skip(20)

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

Acount

Blimit

Cskip

Dsort

Attempts:

3 left

💡 Hint

Common Mistakes

Using skip twice or using count instead of limit.

Placing limit before skip is incorrect; limit should be after skip.

The limit(10) should come after skip(20) to correctly limit the number of documents after skipping.

4fill in blank

hard

Fill both blanks to paginate: skip 15 documents and limit to 7 documents.

MongoDB

db.collection.find().[1](15).[2](7)

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

Askip

Blimit

Csort

Dcount

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping skip and limit methods.

Using sort or count instead of skip or limit.

Use skip(15) to skip 15 documents and limit(7) to limit the result to 7 documents for pagination.

5fill in blank

hard

Fill all three blanks to paginate and sort: skip 5, limit 10, and sort by 'name' ascending.

MongoDB

db.collection.find().[1](5).[2](10).[3]({ name: 1 })

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

Askip

Blimit

Csort

Dcount

Attempts:

3 left

💡 Hint

Common Mistakes

Using count instead of sort.

Incorrect order of methods.

Using sort with wrong syntax.

Use skip(5) to skip 5 documents, limit(10) to limit to 10 documents, and sort({ name: 1 }) to sort by 'name' ascending for pagination.

Practice

1.

What does the skip method do in MongoDB pagination?

easy

A. It limits the number of documents returned.

B. It deletes documents from the collection.

C. It sorts the documents in ascending order.

D. It skips a specified number of documents before returning results.

Solution

1. Step 1: Understand the role of skip

   The skip method tells MongoDB to ignore a certain number of documents from the start of the result set.

2. Step 2: Compare with other methods

   limit controls how many documents to return, not skipping. Sorting and deleting are unrelated to skip.

3. Final Answer:

   It skips a specified number of documents before returning results. -> Option D

4. Quick Check:

   skip = skip documents [OK]

Hint: Skip jumps over documents, limit sets how many to show [OK]

Common Mistakes:

• Confusing skip with limit
• Thinking skip sorts documents
• Assuming skip deletes documents

2.

Which of the following is the correct syntax to get the second page of results with 5 documents per page in MongoDB?

db.collection.find().skip(?).limit(?)

easy

A. skip(1).limit(5)

B. skip(10).limit(5)

C. skip(5).limit(5)

D. skip(0).limit(5)

Solution

1. Step 1: Calculate skip value for page 2

   Each page has 5 documents, so page 1 skips 0, page 2 skips 5 documents (5 * (2-1) = 5).

2. Step 2: Set limit to page size

   Limit should be 5 to get 5 documents per page.

3. Final Answer:

   skip(5).limit(5) -> Option C

4. Quick Check:

   Page 2 skip = 5, limit = 5 [OK]

Hint: Skip = pageSize * (pageNumber - 1), limit = pageSize [OK]

Common Mistakes:

• Using skip(10) for page 2
• Setting skip to 1 instead of 5
• Confusing skip and limit values

3.

Given a collection with documents numbered 1 to 10, what documents will this query return?

db.collection.find().skip(3).limit(4)

medium

A. Documents 1 to 4

B. Documents 4 to 7

C. Documents 3 to 6

D. Documents 5 to 8

Solution

1. Step 1: Understand skip(3)

   Skip the first 3 documents: documents 1, 2, and 3 are ignored.

2. Step 2: Apply limit(4)

   Return the next 4 documents after skipping: documents 4, 5, 6, and 7.

3. Final Answer:

   Documents 4 to 7 -> Option B

4. Quick Check:

   Skip 3, then limit 4 = docs 4-7 [OK]

Hint: Skip removes first N, limit picks next M documents [OK]

Common Mistakes:

• Counting skip as inclusive
• Starting limit count before skip
• Off-by-one errors in document numbers

4.

Identify the error in this pagination query to get page 3 with 10 documents per page:

db.collection.find().skip(20).limit(20)

medium

A. limit should be 10, not 20

B. skip value is too high

C. skip should be 30 for page 3

D. No error, query is correct

Solution

1. Step 1: Calculate correct skip and limit for page 3

   Skip should be 10 * (3-1) = 20, which is correct here.

2. Step 2: Check limit value

   Limit should be 10 to get 10 documents per page, but query uses limit(20), which is too many.

3. Final Answer:

   limit should be 10, not 20 -> Option A

4. Quick Check:

   Limit = page size = 10 [OK]

Hint: Limit equals page size, skip = pageSize*(page-1) [OK]

Common Mistakes:

• Setting limit equal to skip
• Using skip as page number
• Assuming no limit needed

5.

You want to display page 4 of a product list with 8 items per page. However, the total products are 30. Which query correctly handles this pagination without returning empty results?

db.products.find().skip(?).limit(?)

hard

A. skip(24).limit(8)

B. skip(32).limit(8)

C. skip(16).limit(8)

D. skip(30).limit(8)

Solution

1. Step 1: Calculate skip for page 4

   Skip = 8 * (4-1) = 24 documents to reach page 4.

2. Step 2: Check total documents and limit

   Total is 30, so skipping 24 leaves 6 documents (30-24). Limit 8 is okay; it will return only available 6 documents without error.

3. Step 3: Analyze other options

   skip(32) and skip(30) exceed total documents, returning empty results. skip(16) is for page 3, not page 4.

4. Final Answer:

   skip(24).limit(8) -> Option A

5. Quick Check:

   Page 4 skip = 24, limit = 8, total 30 [OK]

Hint: Skip = pageSize*(page-1), limit = pageSize, check total docs [OK]

Common Mistakes:

• Skipping beyond total documents
• Using wrong skip for page number
• Ignoring total document count