How to save template in cache?

Discussed in https://github.com/toddams/RazorLight/discussions/484

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^{Originally posted by alekdavisintel May 31, 2022} The README example shows how to render template from cache, but how do you add it to cache? I.e. what should happen if the cacheResult.Success is false?

var cacheResult = engine.Handler.Cache.RetrieveTemplate("templateKey");
if(cacheResult.Success)
{
	var templatePage = cacheResult.Template.TemplatePageFactory();
	string result = await engine.RenderTemplateAsync(templatePage, model);
}

Here is my code outline (my templates come from strings):

string tempateKey = "XYZ"; 
string templateHtml = "SOME RASOR TEXT"; // Original text has @ placeholders
dynamic model = new ExpandoObject(); // Set some properties below not showing for briefness

var engine = new RazorLightEngineBuilder()
	        .UseMemoryCachingProvider()
	        .Build();

TemplateCacheLookupResult cacheResult = engine.Handler.Cache.RetrieveTemplate(templateKey);

if (cacheResult.Success)
{
    // This code never executes.
    var templatePage = cacheResult.Template.TemplatePageFactory();

    result = await engine.RenderTemplateAsync(templatePage, model);
}
else
{
    // This code always executes.
    result = await engine.CompileRenderStringAsync(templateKey, templateHtml, model);
}

The code never gets into the if (cacheResult.Success) block. What am I doing wrong or not doing at all?

Thanks!

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[dallasbeek]

So what I was seeing was that every generated html document added to the memory. Our simple fix was to register the memorycache as singleton, inject it into our service class and change .UseMemoryCachingProvider() to .UseCachingProvider(_provider). We are using Autofac

register it
builder.RegisterType<MemoryCachingProvider>().As<ICachingProvider>().SingleInstance(); 

inject it
private readonly ICachingProvider _provider;

public DocumentService(ICachingProvider provider)
{
    _provider = provider;
}

use it
var engine = new RazorLightEngineBuilder()
        .UseFileSystemProject($"{Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location)}/Views", string.Empty)
        .UseCachingProvider(_provider)
        .Build();

[jzabroski]

Your problem is you didn’t use a RazorLightProject. I thought I configured it to throw an exception if people did things this way. Long story short, lots of people copy-pasted code from some medium.com article that caused a lot of people bugs, so I “fixed” it to continue without the cache.

See the README - it is the first FAQ in the FAQ: https://github.com/toddams/RazorLight#how-to-use-templates-from-memory-without-setting-a-project