How to Ignore Required Properties on PATCH Request in C- Web API

Learn how to handle PATCH requests in C- Web API by customizing property validation for partial updates. Discover effective strategies for ignoring required properties during updates.
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Handling PATCH Requests in C- Web API: Ignoring Required Properties

In modern web applications, we often need to design our APIs in a way that allows for flexibility in how data is updated. One such scenario that developers frequently encounter is handling PATCH requests where not all properties are sent in a single update, but some properties are required. This poses a challenge, particularly if certain fields should only be required during the creation of a resource (like a Person), while allowing updates to be flexible and optional.

In this guide, we'll explore an effective solution for ignoring required properties during PATCH requests in a C- Web API.

Understanding the Problem

The Data Model

Consider the following data model for a Person:

[[See Video to Reveal this Text or Code Snippet]]

In this structure:

The Status property is required when creating a new Person.

However, when updating an existing Person, we want the Status property to be ignored to prevent modification.

The Challenge

Historically, when an update request is sent, if not all required fields (defined by the [Required] attribute) are included, the API throws exceptions, thus rejecting the request. This is particularly troublesome when users want to send only partial updates:

[[See Video to Reveal this Text or Code Snippet]]

If LastName and Status are missing, the API will fail, leading to a poor user experience.

Solution Overview

To tackle this, we can configure the data model in a way that distinguishes between how the database needs the data (with certain fields declared as required) and how the API accepts data (allowing some fields to be optional during updates).

Step by Step Solution

Model Configuration in Database Context
Modify the OnModelCreating method to specify the behavior of the properties:

[[See Video to Reveal this Text or Code Snippet]]

Define the API Model
Adjust the Person class for the API while utilizing a nullability approach:

[[See Video to Reveal this Text or Code Snippet]]

Using FoolProof Validation
The [RequiredIfEmpty] validation attribute has been introduced from the FoolProof validation library to determine if the fields are required based on the state of the ID. This means:

If ID is missing, then FirstName, LastName, and Status are required for creation.

If ID is present, these fields can be null or omitted for updates.

Conclusion

By architecture the API and database model separately, we effectively manage how properties are validated based on context (insertion vs. update). This tailored approach to validation not only enhances usability but also ensures data integrity.

Implementing this method will allow for more dynamic and user-friendly API interactions, enabling users to perform partial updates without unnecessary errors.

Have you encountered similar issues when designing your APIs? Share your experiences or questions in the comments below!