Skip to main content

Entity Framework Core–Data is null

Last week I had the pleasure to work with a team that started using Entity Framework Core for the first time. They had a lot of experience using NHibernate, so the concept of an ORM was not new. But it was interesting to see which things are obvious when switching to EF Core and which are not.

I thought the team was finally on track after a few bumps in the road when they came back to me with another problem.

When trying to fetch a set of entities, the query failed with the following error message:

System.Data.SqlTypes.SqlNullValueException : Data is Null. This method or property cannot be called on Null values.

This was the object they were trying to fetch:

And here is the LINQ query they were using:

I have to admit that it took me a while before I discovered why this failed.

The reason becomes obvious if you take a look inside the csproj file:

This project had Nullable Reference Types enabled.  If this is enabled and you have a required property that shouldn’t be null, EF Core will throw the error above when the database query returns a NULL value.

The solution was to mark the correct properties as nullable inside the entity class:

More information

Working with nullable reference types - EF Core | Microsoft Learn

Popular posts from this blog

DevToys–A swiss army knife for developers

As a developer there are a lot of small tasks you need to do as part of your coding, debugging and testing activities.  DevToys is an offline windows app that tries to help you with these tasks. Instead of using different websites you get a fully offline experience offering help for a large list of tasks. Many tools are available. Here is the current list: Converters JSON <> YAML Timestamp Number Base Cron Parser Encoders / Decoders HTML URL Base64 Text & Image GZip JWT Decoder Formatters JSON SQL XML Generators Hash (MD5, SHA1, SHA256, SHA512) UUID 1 and 4 Lorem Ipsum Checksum Text Escape / Unescape Inspector & Case Converter Regex Tester Text Comparer XML Validator Markdown Preview Graphic Color B

Help! I accidently enabled HSTS–on localhost

I ran into an issue after accidently enabling HSTS for a website on localhost. This was not an issue for the original website that was running in IIS and had a certificate configured. But when I tried to run an Angular app a little bit later on http://localhost:4200 the browser redirected me immediately to https://localhost . Whoops! That was not what I wanted in this case. To fix it, you need to go the network settings of your browser, there are available at: chrome://net-internals/#hsts edge://net-internals/#hsts brave://net-internals/#hsts Enter ‘localhost’ in the domain textbox under the Delete domain security policies section and hit Delete . That should do the trick…

Azure DevOps/ GitHub emoji

I’m really bad at remembering emoji’s. So here is cheat sheet with all emoji’s that can be used in tools that support the github emoji markdown markup: All credits go to rcaviers who created this list.