I've recently started working on a project with Entity Core Framework in C#, and my question is related to 2 configuration methods for the fields of an entity. As you probably already know each entity has a special ConfigurationFile in which the properties of the fields are specified programatically in order to implement them in the database. I've noticed there are 2 methods: HasColumnType(...) and HasPrecision(...) which at a first glance seem quite similar. My question is what are the differences between them if there are any? And if you could also provide an example for the differences it would be awesome.
I've already looked rapidly on these pages in Microsoft documentation, but for the moment I can't figure out any major difference. I put the links below. I've also asked the well-known ChatGpt and it says there might be some minor differences regarding how the number of digits for scale and precision are counted, but I would like some confirmation. In short, if using both on a property (if possible), what is the simplest formula to make sure you have the same scale and precision both in the database and in the code?
Hope I've made myself clear. Thanks in advance!
As usual the "well-known ChatGpt" is wrong.
There is a major difference between these two definitions in a way that HasColumnType is a database specific, while the HasPrecision is database agnostic.
In other words, the former requires specifying string with valid data type for a specific database. In contrast the later just specifies the desired precision and scale, and let the database provider map it to its specific data type.
The same applies for IsUnicode (the agnostic way to specify database specific varchar vs nvarchar), IsFixedLength(to choose between varchar and char) and HasMaxLength. All these can be replaced with single HasColumnType.
The main benefit of database agnostic attributes / fluent APIs is that you (as C# / .NET developer) don't need to know the concrete database types, and also you can target multiple database types with single data type configuration.
But if you are targeting single specific database and you do know its data types, you can use either ways. Still abstracts are preferable.
Using (mixing) both on a property is discouraged though. The precedence/overriding rules are unclear, and may change between EF versions.