Multiple filter parameters in Rest API - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does 'multiple filter parameters' mean in a REST API?

It means sending more than one condition in the API request to get specific data. For example, filtering users by age and city at the same time.

beginner

How are multiple filter parameters usually sent in a REST API request?

They are sent as query parameters in the URL, separated by '&'. For example: ?age=25&city=London.

beginner

Why use multiple filter parameters in an API?

To get more precise results by combining conditions, like finding products that are both in stock and under a certain price.

intermediate

What is a common challenge when handling multiple filter parameters?

Making sure the API correctly understands and applies all filters together, especially when some filters are optional or have different data types.

beginner

Give an example of a REST API URL with multiple filter parameters.

Example: https://api.example.com/products?category=books&price_lt=20&in_stock=true filters products that are books, cost less than 20, and are in stock.

How do you separate multiple filter parameters in a REST API URL?

A ?

B /

C #

D &

Multiple query parameters are separated by '&' in the URL.

What is the purpose of using multiple filter parameters in an API request?

A To get more specific results

B To get broader results

C To slow down the server

D To change the API version

Multiple filters narrow down the data to more specific results.

Which part of the URL contains filter parameters?

A Path

B Protocol

C Query string

D Fragment

Filter parameters are sent in the query string after the '?' symbol.

If you want to filter users by age and city, how would the URL look?

A /users?age=30&city=Paris

B /users/age=30/city=Paris

C /users#age=30&city=Paris

D /users?age=30#city=Paris

Query parameters are added after '?' and separated by '&'.

What should an API do if a filter parameter is missing?

A Return an error

B Ignore that filter and continue

C Stop processing

D Change the filter automatically

APIs usually ignore missing optional filters and return results accordingly.

Explain how multiple filter parameters work in a REST API and why they are useful.

Think about how you ask for specific data by adding conditions in the URL.

Describe a common way to handle multiple filter parameters on the server side.

Consider what the server does after receiving the URL with filters.

Practice

1. What does adding multiple filter parameters in a REST API URL do?
example.com/api/items?color=red&size=medium

easy

A. Returns items that match all filter conditions (color red AND size medium).

B. Returns items that match any one of the filter conditions (color red OR size medium).

C. Returns all items ignoring the filters.

D. Returns an error because multiple filters are not allowed.

Solution

1. Step 1: Understand multiple filters in URL

   Multiple filters joined by & mean the server should apply all conditions together.

2. Step 2: Interpret the example URL

   The URL ?color=red&size=medium means items must be red AND medium size.

3. Final Answer:

   Returns items that match all filter conditions (color red AND size medium). -> Option A

4. Quick Check:

   Multiple filters = AND condition [OK]

Hint: Multiple filters joined by & mean AND condition [OK]

Common Mistakes:

• Thinking filters work as OR instead of AND
• Assuming filters are ignored
• Believing multiple filters cause errors

2. Which of the following is the correct syntax to filter items by category=books and author=doe in a REST API URL?

easy

A. example.com/api/items?category=books;author=doe

B. example.com/api/items?category=books&author=doe

C. example.com/api/items?category=books|author=doe

D. example.com/api/items?category=books author=doe

Solution

1. Step 1: Identify correct separator for multiple filters

   In URLs, multiple query parameters are separated by &.

2. Step 2: Check each option

   Only example.com/api/items?category=books&author=doe uses & correctly between filters.

3. Final Answer:

   example.com/api/items?category=books&author=doe -> Option B

4. Quick Check:

   Use & to separate filters [OK]

Hint: Use & to separate multiple filters in URL [OK]

Common Mistakes:

• Using | or ; instead of &
• Leaving spaces between parameters
• Not using any separator

3. Given the REST API call:
GET /products?color=blue&size=large&in_stock=true
What kind of products will the server return?

medium

A. Products that are blue AND large AND in stock.

B. Products that are blue OR large OR in stock.

C. Products that are either blue or large, ignoring stock status.

D. All products regardless of filters.

Solution

1. Step 1: Understand multiple filters joined by &

   Filters combined with & mean all conditions must be true together.

2. Step 2: Apply to given filters

   Only products that are blue, large, and in stock will be returned.

3. Final Answer:

   Products that are blue AND large AND in stock. -> Option A

4. Quick Check:

   Multiple filters = AND condition [OK]

Hint: Multiple filters joined by & mean AND condition [OK]

Common Mistakes:

• Thinking filters combine with OR
• Ignoring some filters
• Assuming filters are optional

4. You wrote this URL to filter users by age=30 and active=true:
example.com/api/users?age=30&active=true&
But the server returns an error. What is the likely problem?

medium

A. The URL should use commas instead of &.

B. The server does not support filtering by age.

C. The filter values must be in quotes.

D. The trailing & at the end causes a syntax error.

Solution

1. Step 1: Check URL syntax for filters

   A trailing & at the end of query parameters is invalid syntax.

2. Step 2: Understand server error cause

   The server likely rejects the URL because of the extra & with no following parameter.

3. Final Answer:

   The trailing & at the end causes a syntax error. -> Option D

4. Quick Check:

   Trailing & causes error [OK]

Hint: Avoid trailing & in URL query parameters [OK]

Common Mistakes:

• Leaving trailing & at end of URL
• Using commas instead of &
• Assuming quotes are needed around values

5. You want to get all orders from the REST API where status is shipped and total is greater than 100. The API supports filtering by multiple parameters but only exact matches. How can you combine filters to get orders with status=shipped and total>100?

hard

A. Use ?status=shipped&total=100 and filter results manually.

B. Use ?status=shipped&total=gt:100 to specify greater than.

C. Use ?status=shipped&total_min=101 if the API supports range filters.

D. Use ?status=shipped&total>100 directly in URL.

Solution

1. Step 1: Understand API filter limitations

   The API only supports exact matches, so direct > operator is not allowed.

2. Step 2: Use API-supported range filter parameter

   Many APIs use parameters like total_min to filter values greater than a number.

3. Step 3: Combine filters correctly

   Using ?status=shipped&total_min=101 filters orders with status shipped and total greater than 100.

4. Final Answer:

   Use ?status=shipped&total_min=101 if the API supports range filters. -> Option C

5. Quick Check:

   Use API range params for > filters [OK]

Hint: Use API-specific range filters like total_min for > conditions [OK]

Common Mistakes:

• Trying to use > directly in URL
• Assuming all APIs support gt: syntax
• Filtering manually after fetching all data