EntityType: EntitySet ‘[Entity Name]’ is based on type ‘[Entity Name]’ that has no keys defined

So, the exception completely indicates to us that it is not able to find a Key in the model, which is defined in the database for that entity.

Problem

When you design a model class for the entity, you define many properties including keys, if any. But how MVC would know that some property is a key and some other is a normal? There should be some rule, right? Yes, there is. And if you don’t follow that rule, you would definitely get the below exception.

EntityType: EntitySet '[Entity Name]' is based on type '[Entity Name]' that has no keys defined.

Solution

MVC will automatically recognize an entity’s Key if it follows the convention ‘Id’ or ‘EntityNameId’. Additionally, the entity must expose this as a PROPERTY AND it must be PUBLIC. If you don’t follow the convention, then you need to explicitly indicate that particular property as a Key by using an annotation.

Let’s explore more below.

Example

Convention ‘Id’ or ‘EntityNameId’

public int Id { get; set; }

public int EntityNameId { get; set; }

Using [Key] Attribute

Just put [Key] on top of your property (which is presenting primary key). Something like this.

[Key]
public int AnyName { get; set; }

Hope this Helps !!!

If you landed on this page by searching for the issue somewhere, then I would like you to comment here if you have more queries or doubts. Thanks for reading the blog.

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Written by

Tadit Dash

As a 🚀 Vice President with over 12 years of experience, I am a seasoned software architect known for designing and leading teams of engineers to deliver high-quality software products promptly and within budget. Throughout my career, I have spearheaded the end-to-end design of 7 innovative software products 🎯. From conceptualization to deployment planning, I have successfully guided teams through requirements gathering, prototyping, testing, and deployment phases, ensuring exceptional outcomes. I take pride in my industry recognition, including being honored as a 💎 Microsoft Most Valuable Professional, 💡 CodeProject Most Valuable Professional, and 🏆 DZone Most Valuable Blogger. Additionally, my expertise has been acknowledged by BookAuthority, which recognized my books on ASP.NET, REST API, Vue.js, and Dependency Injection as the 📚 best of all time. In addition to my professional achievements, I am passionate about mentorship and have been privileged to serve as a 🌟 Young Mentor at IndiaMentor, guiding aspiring professionals in their career journeys. For further information about my work and insights, please visit my website at 🌐 http://taditdash.com. You can also connect with me on 🐦 Twitter at https://twitter.com/taditdash, 👍 Facebook at https://www.facebook.com/taditdash, and 💼 LinkedIn at https://www.linkedin.com/in/taditdash. I am always open to networking and discussing opportunities, so feel free to reach out and connect. Let's explore how we can collaborate and drive innovation in the ever-evolving world of software architecture and development.