For strongly typed models, the model type must be accessible

[angelaki]

I'm using RazorEngineCore in an environment with some lazy loaded modules - where RazorEngineCore is one. If I now try to compile a strongly typed model (https://github.com/adoconnection/RazorEngineCore/wiki/Strongly-typed-model) with a type argument that is only accessible within my project (e.g. internal record TestModel(string Name);) the compiler throws an RazorEngineCore.RazorEngineCompilationException.

If this is by design, I don't mind. Just want to make sure, since I'm using private, class-scope based models.

Just out of curiosity: are there any speed advantages (or any others I'm missing) of using strongly typed templates? Since I'm abstracting the implementation by an interface (similar to https://bakson.dev/2022/11/10/razor-engine-core.html IRazorService) I'm asking myself if I even have any advantages by strongly typing the templates.

[angelaki]

@adoconnection sorry for bumping but an information about the advantages of strongly typed models would be pretty handy :) Right now thinking about what method to prefer. Thank you!

[adoconnection]

Hi, I apologize for delay 🙏

1. Yes, strongly typed model has to be public.

As far as I remember its due to it has to be compiled in real-time and otherwise Roslyn cant access it.

You can explore this process here: https://www.codeproject.com/articles/Building-String-Razor-Template-Engine-with-Bare-Ha#comments-section

2. Strongly typed model

There are two things that slowing you down – compiling template and dynamic model. I never measured performance but its easy to spot that compiling is REALLY slow, while dynamic probably adds few milliseconds.

For dynamic model everything has to be wrapped with as DynamicObject including every list and dictionary entry. Unless you dont have big lists you are fine

RazorEngineCore/RazorEngineCore/AnonymousTypeWrapper.cs

Lines 42 to 59 in 64f3b34

	if (result is IDictionary dictionary)
	{
	List<object> keys = dictionary.Keys.Cast<object>().ToList();
	foreach(object key in keys)
	{
	if (dictionary[key].IsAnonymous())
	{
	dictionary[key] = new AnonymousTypeWrapper(dictionary[key]);
	}
	}
	}
	else if (result is IEnumerable enumerable and not string)
	{
	result = enumerable.Cast<object>()
	.Select(e => e.IsAnonymous() ? new AnonymousTypeWrapper(e) : e)
	.ToList();
	}

Haha back then the whole point of making RazorEngineCore was to introduce Saving and Loading compiled templates that basically saves assembly bytes to stream and or calls Assembly.Load to bring it back (way faster than compiling)

RazorEngineCore/RazorEngineCore/RazorEngineCompiledTemplateT.cs

Lines 15 to 16 in 64f3b34

	Assembly assembly = Assembly.Load(meta.AssemblyByteCode, meta.PdbByteCode);
	this.TemplateType = assembly.GetType(meta.TemplateNamespace + ".Template");

My personal preference

My personal preference for typed model is freedom of making variables and helper functions and to be no longer bound by classic Model convention.

Say you have a List<Image> of Gallery template/component
Normally you might end up writing following:

@foreach(Image image in this.Model.Images)
{
    if (image.typeId == 1)
    {
        <img src="@image.url" />
    }
    else if (image.typeId == 2)
    {
        <img src="@Url.Action("ImageHandler", new { id = image.id })" />
    }
}

most likely here you convert your domain model to view model

@foreach(ImageDTO image in this.Model.Images)
{
    <img src="image.Url" />
}

With RazorEngineCore strongly typed model I can declare public string Url(Image image) function in template base.
Similar to making @Url extension methods but instead of global Html helper you have nicely localized logic in template base.
its similar to @Raw https://github.com/adoconnection/RazorEngineCore/wiki/@Raw

@foreach(Image image in this.Images)
{
    <img src="@Url(image)" />
}