🐛 Enum data type is not applied when a member has both [StringLength] and [EnumDataType] annotations

[cervengoc]

Describe the Bug

In our EF Core data layer, in most cases enums are mapped as strings. So we have several classes where a member has both [StringLength] and [EnumDataType] attributes. When using AutoFixture to create an instance of such a class, the latter attribute is disregarded.

Scenario

public enum TestEnum {
    One = 1,
    Two,
    Three
}

public class Test {
    [StringLength(64)]
    [EnumDataType(typeof(TestEnum))]
    public string EnumAsString { get; set; }
}

Expected Behavior

I'd expect that the [EnumDataType] attribute has a stronger precedence as it's more strict than a string length.

Tasks

• Updated all AutoFixture and related libraries
• Confirmed in support forums if behavior is expected

More Information

As I digged into the source code I saw that EnumDataTypeAttributeRelay is after StringLengthAttributeRelay in the Fixture constructor. Seems to me that it should be before that, and it would instantly solve the issue.

Thanks!

EDIT: I'm aware of built-in options to map enums as strings in EF Core. It's a rather old codebase, and right now we're not able to do such a refactor.

[cervengoc]

Hi @aivascu ,
Is there any update on this one? The need for some kind of a fix has just come up again.
Best regards

[aivascu]

Hi @cervengoc ,
I'll have a look today if I can find a workaround. Even if fixed it will go into the next major version which is currently in preview.

[aivascu]

@cervengoc so, as a workaround for prioritizing the data annotations attributes differently, or adding support for more attributes, it's possible to insert a new customization node at the front of the Fixture.Customizations collection.
You should be able to encapsulate this behavior into a ICustomization implementation and reuse it across the codebase.

var builder = new CompositeSpecimenBuilder(
        new EnumDataTypeAttributeRelay(),
        new EnumRangedRequestRelay(),
        new RegularExpressionAttributeRelay(),
        new TimeSpanRangedRequestRelay(),
        new RangeAttributeRelay(),
        new NumericRangedRequestRelay(),
        new MinAndMaxLengthAttributeRelay(),
        new StringLengthAttributeRelay());
fixture.Customizations.Insert(0, builder);

I'll postpone a permanent fix until I decide how to address this request in combination with #1091 and #1348.

Full code

public class UnitTests
{
  [Fact]
  public void Foo()
  {
      var fixture = new Fixture().Customize(new CustomDataAnnotationsCustomization());

      var actual = fixture.Create<TestType>();

      actual.EnumAsString.Should().BeOneOf("One", "Two", "Three");
      actual.RegexString.Length.Should().Be(15);
  }
}

public enum TestEnum
{
  One = 1,
  Two,
  Three,
}

public class TestType
{
  [StringLength(64)]
  [EnumDataType(typeof(TestEnum))]
  public string EnumAsString { get; set; }

  [StringLength(12)]
  [RegularExpression("^[A-Z]{15}")]
  public string RegexString { get; set; }
}

public class CustomDataAnnotationsCustomization : ICustomization
{
  public void Customize(IFixture fixture)
  {
      var builder = new CompositeSpecimenBuilder(
          new EnumDataTypeAttributeRelay(),
          new EnumRangedRequestRelay(),
          new RegularExpressionAttributeRelay(),
          new RangeAttributeRelay(),
          new NumericRangedRequestRelay(),
          new TimeSpanRangedRequestRelay(),
          new StringLengthAttributeRelay(),
          new MinAndMaxLengthAttributeRelay());
      fixture.Customizations.Insert(0, builder);
  }
}

[cervengoc]

Thank you for the workaround suggestion, looks reasonable for now, especially as we already have a bunch of customizations around.