SonarLint Visual Studio Extension / C# Linter

I’m currently working on a legacy code base that’s not a shining example of clean code and best practices.

I try to improve the code as I work, a careful balancing act where I do my best not to impact productivity by spending too much time on refactoring and reformatting.

To help me with this task I decided to look into linters. Note that I’m not using ReSharper which would help with code quality, but that’s another story.

I tried StyleCop, but with the default settings I just wasn’t impressed. Many rules are in my opinion needlessly restrictive. It also seemed to simply dump more than a thousand warnings in the error window.

I tried SonarLint next and I must say I was thoroughly impressed. Though the errors are also sent to the error window they are also shown inline in the file. The parsing by SonarLint was fast and running the Visual Studio extension only had a very small impact on performance even while working with a solution containing thousands of files and hundreds of thousands of lines of codes.

While I haven’t run ReSharper in years, performance was one of the two reasons I stopped using it. On large solutions like the one I’m currently working with, it would slow everything down to a crawl, even when disabling solution-wide analysis.

SonarLint isn’t exactly what I was expecting it to be. I thought it would be more for style guidelines but it has instead given me deeper insights. I’m specifically referring to my last two examples.

Things like needlessly nested if statements:

if (FirstProperty == false) 
{
    if (NeedlesslyDeeplyScoped == true)
    { }
}

Using a Count() instead of an Any:

if (files.Count(f => f.IsDeleted) > 0)
// to
if (files.Any(f => f.IsDeleted))

To foreach statements that can run on null variables:

List<Foo> myCollection = null;

if (IsWeatherRainy) 
{
    myCollection = new List<Foo>();
    // add stuff
}

// myColllection null on at least one execution path
foreach (var item in myCollection)

Or overlapping method signatures with optional parameters that can’t be used:

// This method's signature overlaps the second one
// and the default parameter value can't be used
public File GetFile(bool firstParam, 
                    bool secondParam = false)
{
    return new File();
}

public TestFile GetFile(bool firstParam)
{
    return new TestFile();
}

This last one having been found three times in a single file.

SonarLint is available on the Visual Studio marketplace. It’s free and open sourceĀ with a repository on GitHub. It’s created by a company that also sells a similar product (though geared towards CI / Build servers) but I haven’t found any downsides to using the free Visual Studio Extension.

By the way, I haven’t been asked to write this by the company that makes SonarLint.

Integrating DropzoneJS into an ASP.NET MVC site

Dropzone allows you to easily handle file upload via drag and drop.

Here is a simple tutorial on how to integrate DropzoneJS into an existing ASP.NET MVC application. The instructions on the dropzone page are easy to follow but I include here a version tailored for ASP.NET MVC.

First off, there is a NuGet package but I prefer not to use it so that I can include only the necessary files and choose where those files are located.

The first step is to obtain the JavaScript file and include it into your /Scripts folder.

dropzone1

Optionally you can also download and use the CSS file. Put this one in your /Content folder.

dropzone2

Once these files are in place, it’s time to create some bundles. In App_Start/BundleConfig.cs add the following bundles:

bundles.Add(new ScriptBundle("~/bundles/dropzone")
            .Include("~/Scripts/dropzone.js"));

bundles.Add(new StyleBundle("~/Content/dropzone-css")
            .Include("~/Content/dropzone.css"));

On the page you want to use dropzone on, add calls to the Styles and Scripts render methods and also a form element with the dropzone class. The class name is how dropzone locates the control so it can make the appropriate modifications.

Remember that you can’t nest form elements so if your page already contains another form your will need to make sure they aren’t nested.

Here is how our page.cshtml:

@Styles.Render("~/Content/dropzone-css")

<div class="jumbotron">
    <h1>dropzone test</h1>
</div>

<div class="row">
    @using (Html.BeginForm("FileUpload", "Home", 
                           FormMethod.Post,
                           new
                           {
                               @class = "dropzone",
                               id = "dropzone-form",
                           }))
    {
        <div class="fallback">
            <input name="file" type="file" multiple />
        </div>
    }
</div>

@section scripts {
    @Scripts.Render("~/bundles/dropzone")

    <script type="text/javascript">
        Dropzone.options.dropzoneForm = {
            paramName: "file",
            maxFilesize: 20,
            maxFiles: 4,
            acceptedFiles: "image/*",
            dictMaxFilesExceeded: "Custom max files msg",
        };
    </script>
}

The form contains an optional fallback element for clients who don’t support JavaScript. Also note in the scripts section, custom configuration options are declared.

You may notice I have set a maxFilesize. This value is in MB. It is necessary to change the maxRequestLength attribute in your web.config file to a value at least as big as maxFilesize, otherwise IIS will reject files under the maxFilesize limit.

Here is how to change your maxRequestLength:

<system.web>
    <compilation debug="true" targetFramework="4.5.2" />
    <!--maxRequestLength increased to 20 MB-->
    <httpRuntime targetFramework="4.5.2" 
                 maxRequestLength="20480" />
</system.web>

After we have updated our web.config we can now move on to the controller.

[HttpPost]
public ActionResult FileUpload(HttpPostedFileBase file)
{
    try
    {
        var memStream = new MemoryStream();
        file.InputStream.CopyTo(memStream);

        byte[] fileData = memStream.ToArray();

        //save file to database using fictitious repository
        var repo = new FictitiousRepository();
        repo.SaveFile(file.FileName, fileData);
    }
    catch (Exception exception)
    {
        return Json(new { success = false, 
                          response = exception.Message });
    }

    return Json(new { success = true, 
                      response = "File uploaded." });
}

When uploading multiple files at the same time, this method will get called as many times as there are files.

If you want to handle the returned JSON, you need to handle events from dropzone, in this case the complete event.

Here is how the page looks after having uploaded two pictures:

dropzone3

ASP.NET MVC: Dynamically adding an existing View as a Partial View to a parent

Let’s say you have a pre-existing Model/View/Controller. For my purposes I will call it FirstController, FirstModel and the view, Details.

In this post I will explain how to reuse this form and model in another View/Controller which will become it’s parent. I will also show how to dynamically add this child view to the parent via Ajax. This way we can conditionally add the view based on the user’s input.

Here is our pre-existing MVC:

namespace ChildModel.Controllers
{
    public class FirstController : Controller
    {
        public ActionResult Details()
        {
            var model = new FirstModel { Name = "Gilles",
                                         Number = 42 };
            return View(model);
        }

        [HttpPost]
        public ActionResult Details(FirstModel model)
        {
            if (!ModelState.IsValid)
            {
                return View();
            }

            return RedirectToAction("Index", "Home");
        }
    }
}

namespace ChildModel.Models
{
    public class FirstModel
    {
        public string Name { get; set; }
        public int Number { get; set; }
    }
}

With this simple view:

@model ChildModel.Models.FirstModel

<!DOCTYPE html>

<html>
<head>
    <meta name="viewport" content="width=device-width" />
    <title>First - Details</title>
</head>
<body>
<div>
<h1>First - Details</h1>
@using (Html.BeginForm("Details", "First"))
        {
            @Html.LabelFor(model => model.Name, "Name")
            @Html.TextBoxFor(model => model.Name)

            @Html.LabelFor(model => model.Number, "Number")
            @Html.TextBoxFor(model => model.Number)

            <input type="submit" value="Submit" />
        }</div>
</body>
</html>

first1

Here is the existing Model/View/Controller which will eventually become the parent:

namespace ChildModel.Controllers
{
    public class ParentController : Controller
    {
        public ActionResult Index()
        {
            var model = new ParentModel { IsChecked = true };
            return View(model);
        }

        [HttpPost]
        public ActionResult Submit(ParentModel model)
        {
            if (!ModelState.IsValid)
            {
                return View();
            }

            return RedirectToAction("Index", "Home");
        }
    }
}

namespace ChildModel.Models
{
    public class ParentModel
    {
        public bool IsChecked { get; set; }
    }
}
@model ChildModel.Models.ParentModel

<!DOCTYPE html>

<html>
<head>
    <meta name="viewport" content="width=device-width" />
    <title>Parent</title>
</head>
<body>
<div>
<h1>Parent</h1>
@using (Html.BeginForm("Submit", "Parent"))
        {
            @Html.LabelFor(model => model.IsChecked, "Is Checked ?")
            @Html.CheckBoxFor(model => model.IsChecked)

            <input type="submit" value="Submit" />
        }</div>
</body>
</html>

parent1

Let’s start by including First into Parent. We will do the dynamic Ajax part afterwards.

Since we don’t want to include the form in our parent page, because our parent already has a form and submit button, we will take out the fields we want to reuse and put them in their own partial view.

_FirstFields.cshtml:

@model ChildModel.Models.FirstModel

@Html.LabelFor(model => model.Name, "Name")
@Html.TextBoxFor(model => model.Name)

@Html.LabelFor(model => model.Number, "Number")
@Html.TextBoxFor(model => model.Number)

And call this Partial View in First/Details.cshtml:

@using (Html.BeginForm("Details", "First"))
{
    Html.RenderPartial("_FirstFields");

    <input type="submit" value="Submit" />
}

In our ParentModel we will need to add a new property of type FirstModel:

public class ParentModel
{
    public bool IsChecked { get; set; }
    public FirstModel ChildModel { get; set; }
}

In our Parent/Index.cshtml view we can include the partial view. Notice the use of the ViewDataDictionary in RenderPartial. If we simply asked for the view, the model binder wouldn’t be able to get the data back on a Post. The HtmlFieldPrefix in our ViewDataDictionary is set to the name of our child model property.

This will have for effect of changing the Ids and names of the fields on the partial view allowing the model binder to correctly bind the fields.

@using (Html.BeginForm("Submit", "Parent"))
{
    @Html.LabelFor(model => model.IsChecked, "Is Checked ?")
    @Html.CheckBoxFor(model => model.IsChecked)

    Html.RenderPartial("../First/_FirstFields",
                       Model.ChildModel,
        new ViewDataDictionary(Html.ViewData)
        {
            TemplateInfo = new TemplateInfo
            {
                HtmlFieldPrefix = "ChildModel"
            }
        });

    <input type="submit" value="Submit" />
}

Now we have completed the first part by including a child model/view in our parent. Let’s add the Ajax part.

We will remove our RenderPartial and replace it with a div element which will serve to host the dynamic html code. We will also add an Ajax action link to call a new method on our ParentController.

@using (Html.BeginForm("Submit", "Parent"))
{
    @Html.LabelFor(model => model.IsChecked, "Is Checked ?")
    @Html.CheckBoxFor(model => model.IsChecked)

    @Ajax.ActionLink("Add Child Form", "GetChildElement",
                     "Parent",
                    new AjaxOptions
                    {
                        AllowCache = false,
                        InsertionMode =
                                InsertionMode.Replace,
                        HttpMethod = "Get",
                        UpdateTargetId = "childContainer",
                    })
<div id="childContainer"></div>
<input type="submit" value="Submit" />
}

In our ParentController we add the Ajax action method GetChildElement this time setting the prefix manually:

public PartialViewResult GetChildElement()
{
    ViewData.TemplateInfo.HtmlFieldPrefix = "ChildModel";
    return PartialView("../First/_FirstFields");
}

Don’t forget to add Ajax capabilities to your project like detailed here.

And everything should be working.

parent2

Sniptaculous, a C# snippet library

Sniptaculous, a C# snippet library

I’ve just released the first version of Sniptaculous, a Visual Studio C# snippet library.

I think the existing snippets are great. They have parameters and some of them, such as the switch snippet (sw), will expand and make all of the switch cases for you if you use an existing enum as the parameter.

Since I love snippets and I find they speed up development, I’ve made some of my own. Over 50 snippets in fact.

I will continue adding to and refining Sniptaculous. I’m always open to suggestions and pull requests.