Linq syntax error in ASP MVC controller method

Question

I have a Linq query I need to use in my Index method in the page's controller, however I am getting the following error on the "select new" portion of the code:

Error

Cannot implicitly convert type 'System.Linq.IQueryable<AnonymousType#1>' to 'string'

Action method

    public ActionResult Index(string query)
    {

        var agentProductTraining = "";

        if (String.IsNullOrEmpty(query))
        {
            BlankIndex();
        }
        else
        {
            agentProductTraining = from course in db.Course
                                   where
                                       course.CourseDescription.Contains(query)
                                   select new
                                   {
                                       course.CourseCode,
                                       course.CourseDescription,
                                       course.Partner,
                                       course.Status,
                                       course.LastChangeDate,
                                       course.LastChangeOperator
                                   };
        }

        return View(agentProductTraining.ToList());
    }

SLaks · Accepted Answer · 2012-12-17 19:58:30Z

4

As the error clearly states, you cannot assign the result of a LINQ query (IQueryable<T>) to a variable of type string.

You should declare the variable in that line:

var agentProductTraining = select ...

answered Dec 17, 2012 at 19:58

SLaks

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1 Comment

D Stanley Over a year ago

Except it will be scoped in the else block and not available to the return statement.

D Stanley · Accepted Answer · 2012-12-17 20:05:08Z

1

You've initialized the variable as a string, so the compiler makes the variable a string type (since you've user the var keyword), but then tried to assign a collection of anonymous types to it.

You can declare it as an object instead or var:

object agentProductTraining;  // can safely be overwritten

Also I assume you mean:

return BlankIndex();

in the if block. Otherwise it will fall through to

return View(agentProductTraining.ToList());

where agentProductTraining is going to be null

Of course if you use return BlankIndex in the if block you can simplify the whole thing:

if (String.IsNullOrEmpty(query))
{
    return BlankIndex();
}

// don't need an `else` here since the if will return to the caller
var agentProductTraining = from course in db.Course
                           where
                               course.CourseDescription.Contains(query)
                           select new
                           {
                               course.CourseCode,
                               course.CourseDescription,
                               course.Partner,
                               course.Status,
                               course.LastChangeDate,
                               course.LastChangeOperator
                           };

return View(agentProductTraining.ToList());

answered Dec 17, 2012 at 20:05

D Stanley

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3 Comments

IyaTaisho Over a year ago

It would be better to do this: var agentProductTraining = new List<object>(); Then your return is a list still and is at the very least newed up.

D Stanley Over a year ago

It doesn't matter - the initialized value will get blown away by the assignment via ToList(). It won't add the items to the initialized list.

D Stanley Over a year ago

Also you're not returning the list, you're returning a View that is initialized with an object in the constructor

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