Data Validation in .NET Core API with Fluent Validation: Best Practices and Examples

Ibrahim Jaber
4 min readMar 15, 2023

Fluent Validation is a powerful and flexible validation library for .NET Core API applications. It provides an easy-to-use and fluent interface for validating complex business rules and data constraints. In this blog post, we’ll walk through a step-by-step process of using Fluent Validation in .NET Core API and solve a fun and complex business problem.

Let’s begin with a brief overview of Fluent Validation.

Fluent Validation is a .NET library that allows you to define validation rules for your models in a fluent way. With Fluent Validation, you can easily define validation rules for properties, model-level validation, and complex business rules.

Now, let’s dive into a complex business problem and see how we can solve it using Fluent Validation.

Imagine we are building a food ordering system. In this system, customers can order different types of food items, such as pizza, burgers, and sandwiches. Each food item has its own set of rules and constraints. For example, a pizza can have a maximum of 5 toppings, while a sandwich cannot have any toppings. Additionally, we need to validate the customer’s address and ensure that it is valid.

To solve this problem, we’ll use Fluent Validation. Let’s start by creating a new .NET Core API project.

Step 1: Install the Fluent Validation NuGet package

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Ibrahim Jaber
Ibrahim Jaber

Written by Ibrahim Jaber

Software developer | Programming and Blockchain enthusiast

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