如何在ASP.NET MVC控制器中的创建GET和POST操作中改善DRY

Question

I'm looking for some help as to how I can make my MVC code more efficient, as I am reusing the same code in my Create GET and POST actions which goes against the DRY principles of MVC.

Specifically I'm using EntityFramework and have a controller that populates a ViewModel with the following code:

public ActionResult Create()
    {

        var fileManagers = from x in db.UserProfiles
                            select x;

        var estimators = from x in db.UserProfiles
                                select x;

        var projectManagers = from x in db.UserProfiles
                            select x;

        var jobStatuses = from x in db.JobStatuses
                            select x;           

        JobViewModel viewModel = new JobViewModel
        {
            Job = new Job(),
            FileManagers = fileManagers.Select(x => new SelectListItem
            {
                Value = x.UserName,
                Text = x.FirstName + " " + x.LastName
            }).ToList(),
            Estimators = estimators.Select(x => new SelectListItem
            {
                Value = x.UserName,
                Text = x.FirstName + " " + x.LastName
            }).ToList(),
            ProjectManagers = projectManagers.Select(x => new SelectListItem
            {
                Value = x.UserName,
                Text = x.FirstName + " " + x.LastName
            }).ToList()
        };

        return View(viewModel);
    }

In my POST function, I'm checking for the model validity, and then writing out the same code again to repopulate my ViewModel if the model is not valid, which is what is shown in the ASP.NET music tutorial at http://www.asp.net/mvc/tutorials/mvc-music-store/mvc-music-store-part-5 .

    [HttpPost]
    [ValidateAntiForgeryToken]
    public ActionResult Create(Job job, string action)
    {

        if (ModelState.IsValid)
        {
            db.Jobs.Add(job);
            db.SaveChanges();
            return RedirectToAction("Index");
        }

        var fileManagers = from x in db.UserProfiles
                           select x;

        var estimators = from x in db.UserProfiles
                         select x;

        var projectManagers = from x in db.UserProfiles
                              select x;

        var jobStatuses = from x in db.JobStatuses
                          select x;

        JobViewModel viewModel = new JobViewModel
        {
            Job = job,
            FileManagers = fileManagers.Select(x => new SelectListItem
            {
                Value = x.UserName,
                Text = x.FirstName + " " + x.LastName
            }).ToList(),
            Estimators = estimators.Select(x => new SelectListItem
            {
                Value = x.UserName,
                Text = x.FirstName + " " + x.LastName
            }).ToList(),
            ProjectManagers = projectManagers.Select(x => new SelectListItem
            {
                Value = x.UserName,
                Text = x.FirstName + " " + x.LastName
            }).ToList()
        };

        return View(viewModel);

    }

Can someone please suggest a better way of doing this? Preferably without adding a seperate ORM layer, as the project is quite small.

Answer 1

Just put all the reused code in a method and call from both action methods, something like

  public ActionResult Create()
        {

            return View(createViewModel(new Job()));
        }

        [HttpPost]
        [ValidateAntiForgeryToken]
        public ActionResult Create(Job job, string action)
        {

            if (ModelState.IsValid)
            {
                db.Jobs.Add(job);
                db.SaveChanges();
                return RedirectToAction("Index");
            }            

            return View(createViewModel(job));
        }

        private JobViewModel createViewModel(Job job)
        {
            var fileManagers = from x in db.UserProfiles
                               select x;

            var estimators = from x in db.UserProfiles
                             select x;

            var projectManagers = from x in db.UserProfiles
                                  select x;

            var jobStatuses = from x in db.JobStatuses
                              select x;

            JobViewModel viewModel = new JobViewModel
            {
                Job = job,
                FileManagers = fileManagers.Select(x => new SelectListItem
                {
                    Value = x.UserName,
                    Text = x.FirstName + " " + x.LastName
                }).ToList(),
                Estimators = estimators.Select(x => new SelectListItem
                {
                    Value = x.UserName,
                    Text = x.FirstName + " " + x.LastName
                }).ToList(),
                ProjectManagers = projectManagers.Select(x => new SelectListItem
                {
                    Value = x.UserName,
                    Text = x.FirstName + " " + x.LastName
                }).ToList()
            };

            return viewModel;
        }

Its what I do anyway, save typing the same stuff twice

Answer 2

Well, seeing as you're using the same set of users for each group in your model, this is a little simpler:

var users = db.UserProfiles
.ToArray()
.Select(x => new SelectListItem
{
    Value = x.UserName,
    Text = x.FirstName + " " + x.LastName
});

var jobStatuses = from x in db.JobStatuses
                  select x;

JobViewModel viewModel = new JobViewModel
{
    Job = job,
    FileManagers = users.ToList(),
    Estimators = users.ToList(),
    ProjectManagers = users.ToList()
};

If you're using this as a form model, you could also create the model like so:

var viewModel = new JobViewModel
{
    Job = job,
    FileManagers = new SelectList(users, "Value", "Text", model.FileManager),
    Estimators = new SelectList(users, "Value", "Text", model.Estimator),
    ProjectManagers = new SelectList(users, "Value", "Text", model.ProjectManager)
};

Assuming, of course, that the various lists are SelectList s and that you have string model properties corresponding to the selected user for each role. Assuming you want to have one method that fills the select lists, you could do something like this:

[HttpGet]
public ActionResult YourActionName()
{
    var model = new JobViewModel
    {
        Job = job,
        FileManager = "some value",
        Estimator = "some value",
        ProjectManager = "some value"
    };

    PopulateModel(model);

    return View(model);
}

[HttpPost]
public ActionResult YourActionName(JobViewModel model)
{
    if(ModelState.IsValid)
    {
        // do something...
        return RedirectToAction("your success action");
    }

    PopulateModel(model);

    return View(model);
}

private void PopulateModel(JobViewModel model)
{
    model.FileManagers = new SelectList(users, "Value", "Text", model.FileManager);
    model.Estimators = new SelectList(users, "Value", "Text", model.Estimator);
    model.ProjectManagers = new SelectList(users, "Value", "Text", model.ProjectManager);
}