ASP.NET MVC 3 Razor Templates VS RenderPartial

Question

I just read this blog post on Razor Templating in ASP.NET MVC 3.

Put simply, i just dont get it!

That is, i don't see why we need this (fairly) complicated code to achieve what can be done IMO easier (and neater) with @RenderPartial ?

Here's what i don't like:

1. The template is stored as a Func<T,HelperResult> delegate?
2. That template delegate is persisted in the Controller ViewData (e.g HttpContext.Current.Items)

The only "benefit" i read from that blog is that a seperate file isn't required for templating, meaning you don't need to re-compile etc.

But i don't see that as a valid argument. Extra files are fine as long as the solution organization isn't compromised.

I prefer using @RenderPartial, as i can keep my markup seperate from the master view, and i can render this both inline (render time) and with jQuery (e.g AJAX event).

Maybe i'm missing something here, but can anyone give some reasons why we should choose Razor Templating over RenderPartial to create re-usable content?

Decibel

Answer 1

Well, you should ask the author of that post about his motivation for presenting this technique.

It certainly illustrates what is possible in Razor. Whether you should use it is a different matter. I personally think that there are alternative techniques that are less complicated (I agree with your points about storing a Func inside of the request context).

• There's @RenderPartial which you already mentioned.
• You can also use the @helper syntax (either as a local helper or a global helper)
• You can write an html helper (and use TagBuilder to assemble the output)
• You can write a child action
• You can write a templated helper

Now that I look at the above list I think MVC might provide too much choice :)

Update To better illustrate how inline templates can be useful I wrote a blog post about using them to call sections with default code: Optional Razor Sections with Default Content.

You can use it to write something like this:

@this.RenderSection("OptionalSection", @<div>Default Content</div>) 

Polymath

Hahah. Free thought is the enemy. Thanks @marcind. :) +1 – Decibel

Out of curiosity (only asking since your on the MVC team), do you have any idea what the motivation was to include Razor Templates? There must have been a need/business case for it. Or is it simply to provide an alternative as you say? – Decibel

Well, we (the MVC team) did not provide "Razor Templates". It's just a blog post written by Imran. We are not saying that that's the way you should write applications. It just happens that it's possible to do that (because of the way Razor works). – Polymath

Ah, didn't know that. Thanks, i'll be sticking with the techniques im confortable with. – Decibel

Answer 2

A common misconception about Razor is that it can't be used outside the context of the ASP.Net MVC framework. It is the most common scenario, however the power of razor engine goes beyond that.

You can define razor templates in a console app or even a library. As a over simplified example, consider an app that sends automated HTML emails to clients. In old days, you would either resort to string concatenation or XSLT transform or something else. Either way, you cannot visually see your markup and manipulation becomes a maintenance nightmare.

With Razor templates, you can define your template as HTML markup where you can easily visualize and test it.

Here's an excellent article that demonstrates this capability: http://www.west-wind.com/weblog/posts/2010/Dec/27/Hosting-the-Razor-Engine-for-Templating-in-NonWeb-Applications

Note: I'm not saying that the link you pointed is showing this, just an example of why you would want to go beyond the methods listed in @marcind's answer.

Ailsa