argument type lambda expression is not assignable to parameter type int error

Question

I have a Major model like this:

public int Id { get; set; }
public string MajorName{ get; set; }
public string Password { get; set; }
public System.DateTime RegisterDate { get; set; }
public string StudentId { get; set; }
public string State { get; set; }
public int FacultyId { get; set; }
public int MajorId { get; set; }
public HttpPostedFileBase ImgFile { get; set; }

So I have a method like this in my repository for the above model:

public Major FindMajorById(int id)
{
    return _dbcontext.Majors.Find(id);
}

In my view I passed the id and I need the name of major:

<td>
    @{
        EducationRepositor.MajorRepository objmajor=new MajorRepository();
     }
     @Html.DisplayFor(objmajor.FindMajorById(modelItem => int.Parse(item.MajorId)).MajorName)
</td>
<td>
    @Html.DisplayFor(modelItem => item.Degree)
</td>

But I get error in my view in this line:

@Html.DisplayFor(objmajor.FindMajorById(modelItem => int.Parse(item.MajorId)).MajorName)

My error:

argument type lambda expression is not assignable to parameter type int

Well yes your FindMajorById method takes an int, and you're providing a lambda expression. What do you expect that to do? — Jon Skeet
So how can i pass the id of my major that is provided by lambda? — Ehsan Akbar
So change your method to take an expression, or change your calling of that method to pass an int ... — Mashton

Jon Skeet Jon Skeet · Accepted Answer · 2014-05-15T13:18:44

I suspect you've basically got your lambda expression and your method call the wrong way round. You may want:

@Html.DisplayFor(modelItem => objmajor.FindMajorById(int.Parse(modelItem.MajorId)).MajorName)

In other words, you're creating a lambda expression which takes a model item, parses its MajorId property, calls FindMajorById, and then uses the MajorName property of the result. That lambda expression is used as the argument to DisplayFor.

I'm not an MVC expert (by any means) so it's not clear how much benefit the lambda expression provides, however - whether you could actually just call the method directly.

argument type lambda expression is not assignable to parameter type int error

4 Answers