Unable to use AutoMapper.Mapper.Map method with ASP.NET Core 3.0 Web API

Question

I am following Pluralsight to learn Web API concepts. I'm trying to map Book entity to the Book DTO object which is defined inside Models folder. But, I am getting below error.

I'm getting error like:

An object reference is required for the non-static field, method, or property 'Mapper.Map(object)'

I could not get much help from google as well. When googled for the same, I found two similar questions here, and here. There, I felt sense but I am not understanding how to apply the same rule in my case.

Can anyone please help me to resolve the issue!

@DanielA.White: When I tried for that, I need to provide `IConfigurationProvider`. How can I get this? — Ashok kumar, Nov 10 '19 at 02:13
https://stackoverflow.com/questions/40275195/how-to-set-up-automapper-in-asp-net-core — Daniel A. White, Nov 10 '19 at 02:14
http://docs.automapper.org/en/latest/Dependency-injection.html#asp-net-core — Lucian Bargaoanu, Nov 10 '19 at 05:01
@LucianBargaoanu: Thank you man, looks like it is working for me. — Ashok kumar, Nov 10 '19 at 11:33

score 0 · Accepted Answer · answered Nov 10 '19 at 11:47

Followed Lucian Bargaoanu suggestion and arrived to below solution.

Write the below code in ConfigureServices method:

services.AddAutoMapper(typeof(Startup));

Introduced constructor dependency, and used IMapper functionality like below:

public class BookResultFilterAttribute : ResultFilterAttribute
{
    private readonly IMapper _mapper;
    public BookResultFilterAttribute(IMapper mapper)
    {
        _mapper = mapper;
    }
    public async override Task OnResultExecutionAsync(ResultExecutingContext context, ResultExecutionDelegate next)
    {
        var resultFromAction = context.Result as ObjectResult;
        if(resultFromAction?.Value == null
            || resultFromAction.StatusCode < 200
            || resultFromAction.StatusCode >= 300)
        {
            await next();
            return;
        }
        resultFromAction.Value =  _mapper.Map<Models.Book>(resultFromAction.Value);
        await next();
    }
}

Unable to use AutoMapper.Mapper.Map method with ASP.NET Core 3.0 Web API

1 Answers1