A .NET-Angular implementation of a LoanCalculator, with an EMI (Equal Monthly Installation) approach to calculating the Loan Repayment Schedule.
Objective: The Objective of this project was to do a quick, high-level refresher on .NET+Angular, with a secondary agenda of giving .NET Aspire a try.
Specs & Design Scalability
Main Feature
The Angular FE will receive user input (with validations) for the loan details, and the API does the calculation with the Repayment Schedule as the API call result.Banker's Rounding is applied at the end of every calculation. Naturally, this would depend on the actual business requirements. One good read on this topic can be found here.
Other Technical Details
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Strong Typing: Money and PercentageRates are custom ValueObjects.
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Unit Testing was implemented on the ValueObjects and the Repayment Schedule.
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A single API Endpoint was implemented, as opposed to the MVC Controllers approach, to keep the implementation clean for serving the needs of the current solution. (Further Readings: Choose between controller-based APIs and minimal APIs | FastEndpoints)
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Documentation Comments were added to this project, for better collaboration between team members.
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When exploring Aspire, it was found that the default Redis caching configuring worked with Blazor, but there was no default implementation for Angular/React at the moment. The default .NET Weather API implementation in both Blazor & Angular were retained to demonstrate this.
Designing to Scale
Even though the Calculation could have been hard-coded in the FE, this implementation approach can better scale in terms of features, for example:
- Different Loan Calculation Approaches This can be implemented by adjusting the API, and e.g. by adding a Radio selection or Dropdown to the FE.
- Configurable Range of Allowed Interest Rates This can be implemented via (i) storing this configurable range in the DB; (ii) An API call to retrieve this range; (iii) Have a sliding scale + Textbox on the FE for the interest rate.
Dependencies
Angular-
Angular >= 17.1
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NPM >= 10.4
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Node >=20.11
.NET
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.NET >= 8.0.200-preview.23624.5
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Visual Studio (Community) >= 17.9.0 Preview 4 (Aspire is still in Preview as of time of writing)
Docker