Expense Splitter: Group Creation & Retrieval System

by Alex Johnson 52 views

Organizing expenses can be a real headache, especially when you're splitting costs with friends, family, or colleagues. That's why a robust group management system is essential for any expense-splitting application. This article delves into the requirements, implementation details, and testing strategies for building a system that allows users to create and retrieve groups within an expense splitter application.

User Story: Organizing Expenses with Groups

At the heart of this feature is the user's need to organize expenses effectively. The core requirement can be summarized as follows:

As a user, I want the system to support creating groups and retrieving my groups so I can organize expenses.

This seemingly simple statement packs a significant punch. It highlights the need for a system that's not just functional but also intuitive and user-friendly. The ability to create groups is the foundation, allowing users to categorize expenses based on trips, events, shared living arrangements, or any other logical grouping. The ability to retrieve these groups is equally crucial, enabling users to quickly access and manage their expenses within the appropriate context.

Story Points and Priority

This feature is estimated at 5 story points, reflecting the complexity involved in implementing the backend logic, database interactions, and API endpoints. Furthermore, it's marked as a high priority, underscoring its importance to the overall user experience and the core functionality of the expense splitter application. Without group management, users would struggle to keep track of shared expenses, making the application less valuable.

Assignment

Olivia is assigned to lead the development of this feature, ensuring focused attention and clear accountability. This allows for streamlined communication and efficient progress tracking throughout the development lifecycle.

Implementation Tasks: Building the Group Management System

To bring this user story to life, several key tasks need to be completed. These tasks encompass the design and implementation of API endpoints, database interactions, and input validation.

1. Implement a POST Endpoint to Create a Group in Supabase

The first step is to create an API endpoint that allows users to create new groups. This endpoint will receive data such as the group name and description (if applicable) and will persist this information in the database. Supabase, a popular open-source alternative to Firebase, is chosen as the backend database for this application. The POST endpoint will handle the creation of new group records in the Supabase database.

This task involves several sub-steps:

  • Defining the API endpoint URL (e.g., /api/groups).
  • Creating a data model for groups, including fields like group_name, created_at, and user_id (the creator of the group).
  • Implementing the logic to insert a new record into the groups table in Supabase.
  • Handling potential errors, such as database connection issues or invalid input data.

2. Implement an Endpoint to Get All Groups for the Current User

Once groups can be created, users need a way to retrieve a list of their groups. This task involves implementing an endpoint that fetches all groups associated with the currently logged-in user. This endpoint will likely be a GET endpoint, retrieving data from the Supabase database.

Key considerations for this task include:

  • Ensuring that the endpoint only returns groups that the user either owns or is a member of.
  • Implementing pagination if the number of groups becomes large, to avoid performance issues.
  • Optimizing database queries to efficiently retrieve the required data.

3. Implement an Endpoint to Get Members for a Given Group

To fully manage groups, users need to see who is participating in each group. This task involves creating an endpoint that retrieves a list of members for a specific group. This will likely involve querying a group_members table in Supabase, which establishes the many-to-many relationship between users and groups.

This task requires careful consideration of:

  • Security: Ensuring that only users who are members of the group can access the member list.
  • Data retrieval: Efficiently querying the database to retrieve the list of members.
  • Data formatting: Presenting the member information in a clear and user-friendly format.

4. Validate Group Creation Input (Such as Non-Empty Name)

Data validation is crucial for maintaining data integrity and preventing errors. This task involves implementing validation logic to ensure that group creation requests include all required information and that the data is in the correct format. A key validation rule is to ensure that the group name is not empty.

Validation can be implemented at multiple levels:

  • Client-side validation: Providing immediate feedback to the user in the user interface.
  • Server-side validation: Ensuring that the data is valid before it's written to the database. This is the most important level of validation.

Test Cases: Ensuring Functionality and Reliability

Rigorous testing is essential to ensure that the group management system functions correctly and reliably. Test cases are divided into two categories: automated/unit tests and manual/UI tests.

Automated/Unit Tests

Automated tests provide a fast and efficient way to verify the correctness of individual components and functions. Three key automated tests are defined:

  • Creating a group inserts the correct record: This test verifies that when a new group is created, the corresponding record is correctly inserted into the Supabase database.
  • Fetching groups returns only groups owned by or belonging to the user: This test ensures that users can only access groups that they are authorized to see.
  • Fetching group members returns the correct list of users: This test verifies that the endpoint for retrieving group members returns the correct list of users for a given group.

These tests should cover various scenarios, including edge cases and error conditions.

Manual/UI Tests (Simple)

Manual tests involve interacting with the system through the user interface to verify that it behaves as expected. The primary manual test involves:

  • Using endpoints with sample data and confirming that groups and members match what is in Supabase: This test verifies that the API endpoints are working correctly and that the data displayed in the UI matches the data stored in the database.

This test can be performed using tools like Postman or by directly interacting with the application's user interface.

Conclusion: Building a Solid Foundation for Expense Splitting

Implementing a robust group management system is a crucial step in building a successful expense splitter application. By focusing on user needs, implementing clear API endpoints, and employing thorough testing strategies, developers can create a system that is both functional and user-friendly. This foundation will enable users to organize their expenses effectively and enjoy a seamless expense-splitting experience.

For more information on best practices in backend development and database management, check out resources like Supabase Documentation.