Bulk import and export in Rest API - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this bulk import API response?

Consider a REST API endpoint that accepts a JSON array of user objects for bulk import. The server responds with a summary JSON object showing how many users were successfully imported and how many failed.

Given the following server response after sending 5 user objects, what is the output?

Rest API

{
  "imported": 4,
  "failed": 1,
  "errors": [
    {"index": 3, "message": "Email already exists"}
  ]
}

A {"imported":4,"failed":1,"errors":[{"index":3,"message":"Email already exists"}]}

B {"imported":5,"failed":0,"errors":[]}

C {"imported":3,"failed":2,"errors":[{"index":1,"message":"Invalid data"},{"index":4,"message":"Missing field"}]}

D {"imported":0,"failed":5,"errors":[{"index":0,"message":"Server error"}]}

💡 Hint

Look carefully at the numbers and error details in the JSON response.

The server response shows 4 users imported successfully and 1 failed with an error at index 3. This matches option A exactly.

🧠 Conceptual

intermediate

Which HTTP method is best suited for bulk export of data?

You want to design a REST API endpoint that allows clients to export large amounts of data in bulk. Which HTTP method should you use?

A GET

B PUT

C POST

D DELETE

💡 Hint

Think about which method is used to retrieve data without changing server state.

GET is the standard HTTP method to retrieve data. For bulk export, clients request data without modifying it, so GET is appropriate.

🔧 Debug

advanced

Why does this bulk import request fail with a 400 error?

Here is a JSON payload sent to a bulk import API:

[{"id":1,"name":"Alice"},{"id":2,"name":"Bob"}, {"id":3,"name":null}]

The server responds with HTTP 400 Bad Request. What is the most likely cause?

A The 'id' fields are not unique.

B The third object has a null value for the 'name' field which is required.

C The JSON array is missing a closing bracket.

D The server does not accept arrays, only single objects.

💡 Hint

Check the data values carefully for required fields.

The 'name' field is likely required and cannot be null. This causes the server to reject the request with 400.

📝 Syntax

advanced

Which JSON payload is correctly formatted for bulk export request filters?

You want to request a bulk export with filters on user status and creation date. Which JSON payload is syntactically correct?

A {"filters": {"status" => "active", "created_after" => "2023-01-01"}}

B {"filters": ["status": "active", "created_after": "2023-01-01"]}

C {"filters": {status: "active", created_after: "2023-01-01"}}

D {"filters": {"status": "active", "created_after": "2023-01-01"}}

💡 Hint

Remember JSON requires double quotes around keys and string values, and uses colons, not arrows.

Option D uses correct JSON syntax with double quotes and colons. Options A, B, and C have syntax errors.

🚀 Application

expert

How many user records will be created after this bulk import API call?

An API accepts a bulk import POST request with this JSON payload:

[{"id":1,"email":"[e-mail]"},{"id":2,"email":"[e-mail]"},{"id":3,"email":"[e-mail]"},{"id":4,"email":"[e-mail]"}]

The API rejects duplicates by email and skips them silently. How many user records will be created?

A 1

B 4

C 3

D 2

💡 Hint

Count unique emails only, duplicates are skipped.

Emails are: [e-mail] (twice), [e-mail], [e-mail]. The duplicate '[e-mail]' is skipped once, so 3 unique users are created.

Practice

1. What HTTP method is commonly used to perform a bulk import of records in a REST API?

easy

A. PUT

B. POST

C. DELETE

D. GET

Solution

1. Step 1: Understand bulk import action

   Bulk import means sending many new records to the server at once.

2. Step 2: Identify HTTP method for creating resources

   POST is used to send data to create new records in REST APIs.

3. Final Answer:

   POST -> Option B

4. Quick Check:

   Bulk import uses POST [OK]

Hint: Bulk import sends data with POST method [OK]

Common Mistakes:

• Choosing GET which is for fetching data
• Using DELETE which removes data
• Confusing PUT with bulk import

2. Which of the following is the correct JSON format to bulk import two user records in a REST API POST request?

easy

A. [{"name": "Alice"}, {"name": "Bob"}]

B. {"name": "Alice", "name": "Bob"}

C. {"users": "Alice, Bob"}

D. ["Alice", "Bob"]

Solution

1. Step 1: Recognize bulk import JSON structure

   Bulk import expects a list (array) of objects, each representing a record.

2. Step 2: Check each option format

   [{"name": "Alice"}, {"name": "Bob"}] is a JSON array with two objects, each with a "name" key. Others are invalid or wrong format.

3. Final Answer:

   [{"name": "Alice"}, {"name": "Bob"}] -> Option A

4. Quick Check:

   Bulk import uses JSON array of objects [OK]

Hint: Bulk import JSON is a list of objects [OK]

Common Mistakes:

• Using a single object with duplicate keys
• Sending a string instead of objects
• Using a simple list of strings without keys

3. Given this REST API response after a bulk export request:

{"users": [{"id":1,"name":"Alice"},{"id":2,"name":"Bob"}]}

What is the value of the second user's name?

medium

A. users

B. Alice

C. 2

D. Bob

Solution

1. Step 1: Locate the users array in the JSON

   The key "users" holds a list of user objects.

2. Step 2: Identify the second user object and its name

   The second object is {"id":2,"name":"Bob"}, so the name is "Bob".

3. Final Answer:

   Bob -> Option D

4. Quick Check:

   Second user's name = Bob [OK]

Hint: Look inside 'users' array, second object's 'name' key [OK]

Common Mistakes:

• Confusing index and picking first user
• Selecting the id instead of name
• Choosing the key name instead of value

4. You try to bulk import records with this JSON:

[{"name": "Alice"}, {"name": "Bob"}

But the server returns a 400 Bad Request error. What is the likely problem?

medium

A. Missing closing bracket in JSON array

B. Using POST instead of GET

C. Names should be numbers, not strings

D. Bulk import requires XML format

Solution

1. Step 1: Check JSON syntax

   The JSON is missing the closing bracket "]" for the array.

2. Step 2: Understand server error meaning

   400 Bad Request often means invalid JSON syntax was sent.

3. Final Answer:

   Missing closing bracket in JSON array -> Option A

4. Quick Check:

   Invalid JSON syntax causes 400 error [OK]

Hint: Check JSON brackets carefully for syntax errors [OK]

Common Mistakes:

• Assuming wrong HTTP method caused error
• Thinking data types must be numbers
• Believing XML is required instead of JSON

5. You want to export all products with price above 100 in bulk from a REST API. Which approach correctly combines bulk export with filtering?

hard

A. Send a DELETE request to /products with filter price>100

B. Send a POST request with JSON [{"price": ">100"}] to /products/export

C. Send a GET request to /products?min_price=100 and parse the returned list

D. Send a PUT request to /products/export with price filter in body

Solution

1. Step 1: Identify correct HTTP method for export

   Bulk export uses GET to retrieve data from the server.

2. Step 2: Use query parameters for filtering

   Filtering by price is done via query string like ?min_price=100.

3. Final Answer:

   Send a GET request to /products?min_price=100 and parse the returned list -> Option C

4. Quick Check:

   Bulk export uses GET with filters in query [OK]

Hint: Use GET with query filters for bulk export [OK]

Common Mistakes:

• Using POST for export instead of GET
• Sending filters in request body for GET
• Using DELETE or PUT incorrectly