Setting base type and setting namespaces

[mcintyre321]

Hi again. I'm trying to replace RazorEngine with RazorLight in my FormFactory project, but am getting some errors when I run my templates.

My templates are very similar to MVC views (in fact they are MVC views when I run them inside MVC, but I read them and change them when running as standalone templates), e.g. one might look like this:

@using System.ComponentModel.DataAnnotations
@using System.Linq
@using System.Xml.Linq
@using FormFactory  

@{
    @Model.GetCustomAttribute<DisplayAttribute>().Name
    var value = Model.Value as XElement;
    if (value != null) { 
        @Html.Raw(value.ToString())
    }
}

So I have using statements, and am using @model and Model and also Html.

I got this to work with RazorEngine by making the template inherit from a base type with Html and Model on it. How can I set the base type with RazorEngine? It looks like Model is set from the .Parse(..., model) but that won't work for Html

-Also I'm getting errors like - The type or namespace name 'DataAnnotations' does not exist in the namespace 'System.ComponentModel' (are you missing an assembly reference?). Is there a way to tell RazorEngine what assemblies to use?- caused by DataAnnotations having a different namespace in 451/standard

thanks!

[toddams]

HTML Helpers are not supported by RazorLight at the moment. @using, however, should work for specifying a namespaces

[mcintyre321]

I have my own type FFHtmlHelper which I want to expose as a property Html on the views base type. Is there a way to set the base type?

Does it just use whatever assemblies are in the current appdomain, or do I need to specifically inject assemblies?

[toddams]

Yep, inheritance is supported.

Create a class:

public class BasePage<T> : TemplatePage<T>
	{
		public override Task ExecuteAsync()
		{
			return Task.FromResult(0);
		}
	}

In your view:

@inherits YourApplicationNamespace.BasePage<dynamic>

Replace dynamic with your model type, or leave it as it is.

About assemblies:
It takes dependencies from entryAssembly, so make sure that you have everything there.

[mcintyre321]

Is there a way to set some properties on the MyBasePage before executing the template?

[toddams]

Yep, here is an example of code I use at RazorLight.MVC to inject properties values before rendering a page:

private static void AddEngineRenderCallbacks(IRazorLightEngine engine, IServiceProvider services)
{
	var injector = services.GetRequiredService<PropertyInjector>();
	engine.Configuration.PreRenderCallbacks.Add(template => injector.Inject(template));
}

Add your custom PreRenderCallback to EngineConfiguration

[toddams]

Is everything clear @mcintyre321?

[mcintyre321]

Not really, but I haven't had a chance to try it out yet!

I'm imagining I'm going to have to do something along the lines of:

class MyPageTempalteType<T> :  : TemplatePage<T>
{
    public HtmlHelper Html {get;set;}
    public override Task ExecuteAsync() => Task.FromResult(0);
}
...

var engine = EngineFactory.CreateEmbedded(typeof(MyPageTemplateType)) 



var injector = engine.services.GetRequiredService<PropertyInjector>();
engine.Configuration.PreRenderCallbacks.Add(template =>  {
    ((MyPageTemplateType) template).Html = GetHtmlHelper();
});

...

var model = new SomePageModel()
{
    Title = "Hello, world",
    Description = "Some text here"
};
string result = engine.Parse("SomePage", model); 

Is that about right?

[toddams]

Part with injector is not correct. Is was just an example of how I use PreRenderCallback to fill in dependencies in templates.

Here is more complete example:

var configuration = EngineConfiguration.Default;

configuration.PreRenderCallbacks.Add(templatePage =>
{
	var page = (YourBaseType)templatePage;

	page.Html = /* Assign your property here */,
	page.MyOtherProperty = "Same here";
});

var engine = EngineFactory.CreatePhysical("C:\\", configuration);

/* Use engine then */

[mcintyre321]

Is it performant to new up a new engine each time, or should it be cached? I may have different values for MyOtherProperty etc.

[toddams]

Yea, that might be a problem. First solution that comes to my mind - is to add "Remove" method to PreRenderActionList, so you can replace a callback before each render

[toddams]

Special for you, I added an additional overload to "Parse" method, which accepts Action<TemplatePage>, so you can add callbacks for each page individually, and not to rely on global PreRenderCallbacks of EngineConfiguration.

Here is a full example:

Code:

string result = engine.Parse("file.cshtml", model: 1337, viewBag: null, prerenderCallback: new Action<TemplatePage>((t) =>
{
	var page = (BasePage<int>)t;
	page.Property = 1337;
}));

View:

@inherits RazorLight.Sandbox.BasePage<int>

<html>
    @Property
</html>

BasePage.cs

public class BasePage<T> : TemplatePage<T>
{
    public int Property { get; set; }
    public override Task ExecuteAsync()
    {
        return Task.FromResult(1);
    }
}

Rendered result:

<html>
    1337
</html>

[toddams]

Let me know if it works for you, so I can finally close this issue :)

[joetherod]

Regrading namespaces, I see there is a collection for namespaces. Can I just add the namespaces there? If so, how? I added them to that collection and it still didnt work. The razor I have uses the namespaces in the web.config, so they are not listed in the actual html.

[mcintyre321]

Thanks for the new feature! I'm still trying to get this to work, have discovered NUnit doesn't work in netcore1.1 which is slowing me down a little...

[mcintyre321]

Still trying to get a custom base type to work...
I tried setting the using a custom PageFactory (in a custom EngineFactory copied from the Embedded one):

      IPageFactoryProvider pageFactory = new DefaultPageFactory((key) =>
            {
                ITemplateSource source = manager.Resolve(key);

                string razorTemplate = core.GenerateRazorTemplate(source, new ModelTypeInfo(typeof(FormFactoryTemplateBase)));
                var context = new CompilationContext(razorTemplate, configuration.Namespaces);

                CompilationResult compilationResult = configuration.CompilerService.Compile(context);

                return compilationResult;
            });

but the template always compiles with TemplatePage<TModel> not FormFactoryTemplateBase* - is it because [BaseType] is a const, and isn't being set from my ModelTypeInfo?

*which inherits TemplatePage

[toddams]

Example that I provided works, I tested it. You cast TemplatePage to your template base type and it works. You don't need custom PageFactory

[mcintyre321]

I see, I had to use an explicit @inherits statement (rather than setting the base type in the factory). It seems to be working now! thanks!