I keep getting "needs to have a constructor with 0 args or only optional args. (Parameter 'type')"

user_12071306 0
Viewed 7896

I am using version 9. I am using a Profile based configuration. When I run the application the Mapper.Map<>() method throws the following exception:

JobAssist.Services.ResumeBankMgmt.API.Application.ViewModels.ResumeBankViewModel needs to have a constructor with 0 args or only optional args. (Parameter 'type')

I don't know what is causing this.

automapper-9 automapper c#
2 Answers

The issue was that I had one parameter that was not named exactly like my class property. See I changed "categories" in constructor to "resumeCategories".

Original code:

public class ResumeBankViewModel
{
        public List<ResumeCategoryViewModel> ResumeCategories { get; set; }


        public ResumeBankViewModel(int id, int jobSeekerID, List<ResumeViewModel> resumes, List<ResumeCategoryViewModel> categories)

new code:

public class ResumeBankViewModel
{
        public List<ResumeCategoryViewModel> ResumeCategories { get; set; }


    public ResumeBankViewModel(int id, int jobSeekerID, List<ResumeViewModel> resumes, List<ResumeCategoryViewModel> resumeCategories)
user_120713060

Assuming you have access to the source code, and this isn't in a 3rd party assembly you're referencing...

Find the definition of the class ResumeBankViewModel (ViewModels\ResumeBankViewModel.cs is probably a good place to start.)

And add this line:

public ResumeBankViewModel(){ }

If there is a line like this:

private ResumeBankViewModel() /* { etc. } */

Or this:

internal ResumeBankViewModel() /* { etc. } */

You might change the private/internal to public.

You may also wish to look at the other public constructors that are already defined and pass some appropriate values to one of them:

public ResumeBankViewModel() : this(value1, value2, value3) { }

Or make it's parameters optional:

public ResumeBankViewModel(object arg1 = value1, object arg2 = value2, object arg3 = value3)

Any of these might lead to more issues that you will need to work through, but one of these is the bare minimum to clear this error.

user_10487990
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