Filtering by field values in Rest API - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this REST API filter query?

Given an API endpoint that returns a list of users, the query ?age=30 filters users by age. What will be the JSON response if the database has users with ages 25, 30, and 35?

Rest API

GET /users?age=30

Response body:

A [{"id":1,"name":"Bob","age":25}]

B [{"id":1,"name":"Bob","age":25},{"id":2,"name":"Alice","age":30},{"id":3,"name":"Eve","age":35}]

C [{"id":2,"name":"Alice","age":30}]

D []

💡 Hint

Filtering by age=30 returns only users with age exactly 30.

The filter query ?age=30 returns only users whose age field equals 30. Only Alice matches this.

❓ Predict Output

intermediate

What does this REST API filter return?

An API supports filtering products by price range using ?min_price=10&max_price=20. If products have prices 5, 10, 15, 20, and 25, which products are returned?

Rest API

GET /products?min_price=10&max_price=20

Response body:

A [{"id":3,"price":15}]

B []

C [{"id":1,"price":5},{"id":2,"price":10},{"id":3,"price":15},{"id":4,"price":20},{"id":5,"price":25}]

D [{"id":2,"price":10},{"id":3,"price":15},{"id":4,"price":20}]

💡 Hint

The filter includes products with price between 10 and 20 inclusive.

The filter returns products priced at 10, 15, and 20. Prices 5 and 25 are outside the range.

🔧 Debug

advanced

Why does this filter query return an error?

A REST API supports filtering users by status with ?status=active. The client sends ?status=activ and gets a 400 error. Why?

Rest API

GET /users?status=activ

A The API expects exact status values; 'activ' is invalid and causes a 400 Bad Request.

B The API does not support filtering by status, so any status query causes error.

C The API expects status values in uppercase, so 'activ' is invalid.

D The API requires status to be a number, not a string.

💡 Hint

Check if the filter value matches allowed values exactly.

The API validates filter values strictly. 'activ' is a typo and not recognized, so it returns 400.

❓ Predict Output

advanced

What is the output of this complex filter query?

An API supports filtering orders by date range and status: ?start_date=2023-01-01&end_date=2023-01-31&status=shipped. Given orders with various dates and statuses, which orders are returned?

Rest API

GET /orders?start_date=2023-01-01&end_date=2023-01-31&status=shipped

Response body:

A [{"id":101,"date":"2023-01-05","status":"shipped"},{"id":102,"date":"2023-01-20","status":"shipped"}]

B [{"id":101,"date":"2023-01-05","status":"shipped"},{"id":103,"date":"2023-02-01","status":"shipped"}]

C [{"id":102,"date":"2023-01-20","status":"pending"}]

D []

💡 Hint

Filters combine to return orders shipped in January 2023 only.

Only orders with status 'shipped' and dates in January 2023 are returned.

🧠 Conceptual

expert

Which option best describes filtering by nested field values in REST APIs?

You want to filter a list of books by the author's country, where author is a nested object. Which approach is correct?

A Filtering nested fields is not possible in REST APIs; you must filter client-side.

B Use a query parameter like <code>?author.country=USA</code> if the API supports nested filtering.

C Send the entire author object in the query string to filter by country.

D Use a header to specify nested field filters instead of query parameters.

💡 Hint

Some APIs allow dot notation in query parameters for nested fields.

Many REST APIs support nested filtering using dot notation in query parameters, like ?author.country=USA.