Cannot implicitly convert type with IEnumerable

[Rasphino]

Hi Amichai, I have a problem when trying to wrap an IEnumerable to an ErrorOr<IEnumerable>:

using ErrorOr;

class Foo {
    public ErrorOr<IEnumerable<int>> wrap() {
        IEnumerable<int> nums = new List<int>(){ 1, 2 };
        return nums;   
    }
}

VSCode gives me an error:

Cannot implicitly convert type 'System.Collections.Generic.IEnumerable<int>' to 'ErrorOr.ErrorOr<System.Collections.Generic.IEnumerable<int>>' [BuberDinner.Api]csharp(CS0029)
No quick fixes available

---

I find a workaround: changes IEnumerable<int> tools to List<int> tools:

using ErrorOr;

class Foo {
    public ErrorOr<IEnumerable<int>> wrap() {
        List<int> nums = new List<int>(){ 1, 2 };
        return nums;   
    }
}

[jorik]

I'm getting the same error:

public async Task<ErrorOr<IReadOnlyList<Dto>>> DoSomething(...) 
{
    var list = await _repository.Get();
    return list.AsDto();
}


 internal static IReadOnlyList<Dto> AsDto(this IEnumerable<DbObject> dbObjects) {
     return dbObjects.Select(AsDto).ToList();
 }

Getting this error:
cannot convert expression type 'System.Collections.Generic.IReadOnlyList<Dto>' to return type 'ErrorOr.ErrorOr<System.Collections.Generic.IReadOnlyList<Dto>>'

[amantinband]

Thanks, @Rasphino, for opening this issue. You are right, implicit conversion won't work with interfaces. I've added an ErrorOr.From method. I'll publish a new version and update the documentation 🙂

[amantinband]

Done: https://github.com/amantinband/error-or#from-value-using-from

Let me know if you still face any issues.

[dozed]

It seems the From method currently only supports the creation from a list of errors, the construction with values doesn't seem to be implemented.

https://github.com/amantinband/error-or/blob/main/src/ErrorOr.cs#L29-L35

[amantinband]

@dozed, have you tried ErrorOr.From(value) (docs, source code)?
It's implemented this way, so you don't need to write ErroOr<ValueType>.From(value)

[dozed]

For some reason this does not compile:

Whereas this does:

Am I doing something wrong here?

[bwong365]

Same here: ErrorOr.From(data) fails to compile while ErrorOr.ErrorOr.From(data) works. It's not the worst; but it does look pretty awkward.

[chrisgilliam72]

try ErrorOrFactory.From(data)