How do I add a custom formatter in ASP.NET and AutoFac

[MorganBard]

Greetings all,

I have created a custom formatter and tried to add it in the Startup routine of an ASP.Net application. Unfortunately, it does not seem to be available later when I try to use it. I get an exception that it can't find the formatter. I worked around the problem by calling

Smart.Default.AddExtensions(formatter);

In the constructor of the classes where I use it. This works, but seems counter-intuitive. Is this the way it's supposed to work or am I doing something wrong?

My thanks :)

Morgan Haldane

[axunonb]

Yes, this does not work

Smart.Default.AddExtensions(formatter);

because the custom extension is registered in a [ThreadStatic] context, and thus an isolated version of the SmartFormatter is created in your current thread.

In ASP.NET you could create a new SmartFormatter instance with all extensions you need, and register it as service with IServiceCollection.AddTransient(...). This way you can inject it where needed. Does this make sense to you?

[MorganBard]

My apologies. Life got super busy over the last few weeks and I had forgotten I posted this. That was rather rude, and you have my apologies.

I do understand the answer in concept. I don't use the built in ASP.Net dependency injection, though. I use AutoFac. Do you know how it would work with that DI framework?

Thanks very much!
Morgan

[axunonb]

For AutoFac the code would be similar to this (untested):

var builder = new ContainerBuilder();
builder.Register(c =>
{
    var formatter = new SmartFormatter();
    // Modify the formatter instance to match your needs
    return formatter;
}).InstancePerDependency();

[MorganBard]

I added a new answer with what I figured out. I had one more question, though. Is there a benefit to using the InstancePerDependency as opposed to SingleInstance? I was thinking the singleton would save some time since I call this fairly often in my code. Is there an issue with doing it as a singleton?

Thanks again,

Morgan

PS. This is great stuff! Thanks for putting it out there for folks to use!

[axunonb]

SmartFormatter is not thread-safe, that's why SingleInstance does not work. The time to create the formatter is negligible in an asp.net context.

[MorganBard]

Good to know! Thanks again.

Morgan

[MorganBard]

Ok, after a bit of research, I got this and it seems to work:

In my ApplicationModule class (where I do all my dependency injection registrations) i have this in the Load method:

builder.Register(c =>
{
   SmartFormatter formatter = new SmartFormatter()
      .AddExtensions(
         new StringSource(),
         // will automatically be added to the IFormatter list, too
         new ListFormatter(),
         new DictionarySource(),
         new ValueTupleSource(),
         new ReflectionSource(),
         // for string.Format behavior
         new DefaultSource(),
         new KeyValuePairSource())
      .AddExtensions(
         new PluralLocalizationFormatter(),
         new ConditionalFormatter(),
         new IsMatchFormatter(),
         new NullFormatter(),
         new ChooseFormatter(),
         new SubStringFormatter(),
         // for string.Format behavior
         new DefaultFormatter());

   IFormatter numberFormatter = c.ResolveNamed<IFormatter>("nbrFormatter");
   formatter.AddExtensions(numberFormatter);

   return formatter;
}).AsSelf().InstancePerDependency();

In the places where I need formatting, I have this:

private readonly SmartFormatter formatter;

public class WorkerClass
{
   // Other constructor stuff here...
   formatter = factory.Create<SmartFormatter>(); // factory is my factory class used to create objects. It uses AutoFac internally.
}

public void WorkerMethod()
{
   int someValue;
   // method does stuff
   string stuff = formatter.Format("{value:nbrFormatter(x)}", new {value = someValue});
   DoSomethingWithStuff(stuff);
}

Initially, I got an error saying I was missing SourceExtensions. I looked up how the default formatter was initialized and copied that code here. The Wiki didn't have anything that I could find, other than a warning to "for the beginning, leave SmartFormatter.Format() alone." I figured it was a more advanced topic, but I couldn't find it anywhere else. So, a little figuring, some searches in the code here and I discovered how to do it. It works just fine, so I thought I'd include it here as a suggested answer for others to find if they needed it.

Thanks,

Morgan

[axunonb]

Adding all extensions can be abbreviated with var formatter = Smart.CreateDefaultSmartFormat(), and then add your customer formatter with formatter.AddExtensions(numberFormatter). For improved performance you might consider to only load the extensions that you actually need.

[MorganBard]

Also good to know! Thanks. Might it be possible to add something about using non-default formatter to the Wiki? If it's editable, I'd be happy add it myself.

Morgan

[axunonb]

Yes, the Wiki is editable. Your welcome to contribute.