Convert Enum From String To Int In DB Then Back To String - Entity Framework Core 3

Question

I have an Enum similar to this:

    public enum Type
    {
        TypeA,
        TypeB,
        TypeC
    }

I have this using Fluent API and Entity Framework 3.0:

    builder.Entity<Element>()
        .Property(p => p.Type)
        .HasConversion<int>();

This converts the string coming in and saves it in the DB as an int. However, when I do a query to pull it out of the DB it is staying an int.

I have read the docs but I cannot seem to understand:

How do I take the string of the Enum - convert it to an int for the DB - then receive a string when I query the DB?

I thought maybe it was using EnumToNumberConverter but it takes two arguments and I have no idea what the second argument should be. As seen in these docs: https://learn.microsoft.com/en-us/ef/core/modeling/value-conversions

Can anyone please give me a concrete example of how I convert an Enum's string to integer when storing in the DB and then when querying it get handed the Enum's string again?

Thank you.

Does this answer your question? Getting attributes of Enum's value — Hameed Syed
– Hameed Syed, Commented Dec 28, 2019 at 4:49

Hadi Samadzad · Accepted Answer · 2019-12-28 05:42:22Z

6

You don't need using convertors, EF Core stores Enums as an Integer. So, using .HasConversion<int>(); is not needed anymore. EF Core reads this value as an Integer and casts it to the Type when you send a query. Therefore, you have a Type that you can use Type.Sample.ToString() to using string value.

answered Dec 28, 2019 at 5:42

Hadi Samadzad

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3 Comments

Eric Belisle Giddings Over a year ago

Thank you for the answer. You're right, I don't need that. It was my front end TypeScript Enum that was casting it back to a number. So it was coming out my API a string again and then in the front end a TS Enum was casting it back to a number. Now to figure out how not to cast it back to a number. I appreciate your help!

Inspi Over a year ago

Do you have a (preferably microsoft) source saying "EF Core stores Enums as Integer" ? I need it to convince other developpers to use enums instead of magic numbers in their entities

Hadi Samadzad Over a year ago

@Inspi I think for persuading to not using magic numbers you don't need an EF-related reference, Either integer constants or Enums can be used for this purpose depending the case

beothunder · Accepted Answer · 2019-12-28 05:36:48Z

0

This will return the enum string:

enum E : int
{
    Element1 = 42
}
//...
int i = 42;
string s = ((E)i).ToString();// returns "Element1"
//...

answered Dec 28, 2019 at 5:36

beothunder

5582 silver badges16 bronze badges

1 Comment

Eric Belisle Giddings Over a year ago

Thank you for the answer, but this wasn't what I was asking. I appreciate it though!

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