IronRuby/RHTML based templates for .NET
Posted by – December 8, 2009
During last few days I was prototyping some of new features I would like to add to ByteCarrot application. One of them is new template engine which will replace current XSLT based solution. I wanted something with more friendly syntax, something easy to create, change and maintain. I took a look at many template engines available for .NET platform but none of them met my needs. I thought that it would be nice to have solution with scripting support and syntax similar to this available in default ASP.NET MVC view engine.
After digging I have found an ASP.NET MVC application prototype with view engine based on IronRuby. It was created by Phil Haack’s team and its syntax was exactly the same as RHTML used in Ruby on Rails views. It turned out that this engine was exactly what I needed, so I have taken parts of the code and adapted it to my scenario. The result is amazing because now I have fully functional templates engine with support of dynamic language where I can handle every possible HTML generation scenario.
As an attachment to this post I have added the code created during prototyping. The code contains few classes where the most important is RhtmlEngine. It has very simple, self-expanatory interface and acts as an “entry point” for using mentioned templates engine. Below you can find two samples showing capabilities of my solution but if you want to take a look at the implementation and make your hands dirty feel free to download the code and play with it for yourself.
public class RhtmlEngine
{
public Result Render(object model, string temlateFile, string targetFile)
...
public Result Render(object model, StreamReader rhtml, StreamWriter writer)
...
}
Simple template
The templates engine requires three things to be able to generate HTML:
- Model representing the data which should be presented in form of HTML page,
- Template defining how model should be presented,
- Target where generated HTML page should be saved.
Listing below shows simple template generating a header and a list of hobbies. Notice that IronRuby blocks are embedded exactly the same as Visual Basic .NET or C# code is embedded in ASP.NET MVC views.
SimpleTemplate.rhtml
<html>
<body>
<h1>Hi! My name is: <%= model.FirstName %><%= model.LastName %></h2>
I like:
<ul>
<% model.Hobbies.each do |hobby| %>
<li><%= hobby %></li>
<% end %>
</ul>
</body>
</html>
Template shown above can be used to generate an HTML representation of the following model:
var model = new SampleModel
{
FirstName = "Marcin",
LastName = "Obel",
Hobbies = new List<string>
{
"yachting",
"fishing",
"cycling"
}
};
As you can notice looking at listing below, because the templates engine is very simple, you need only one line to change the model into HTML page.
var result = new RhtmlEngine().Render(model, "SimpleTemplate.rhtml", "SimpleHtml.html");
In result (as shown below) the code above will produce clean HTML filled in with the data from model.
SimpleHtml.html
<html>
<body>
<h1>Hi! My name is: MarcinObel</h2>
I like:
<ul>
<li>yachting</li>
<li>fishing</li>
<li>cycling</li>
</ul>
</body>
</html>
More advanced example
The example above does not show the most powerful part of this solution which is in fact inherited from IronRuby itself. Because templates are based on fully functional, dynamic language there is a possibility to extend basic features like loops and if statements (available in all templates engines) with things like functions, classes or even use some functionalities available in .NET Framework. Next example extends this one mentioned in previous section. In the listing below you can notice two new functions:
- encode - uses HttpUtility class from .NET Framework to encode HTML code
- render_li – renders an item of HTML list
AdvancedTemplate.rhtml
<%
require 'System.Web, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'
include System::Web
def encode(text)
HttpUtility.HtmlEncode(text)
end
def render_li(text)
writer.Write "<li>#{text}</li>";
end
%>
<html>
<body>
<h1>Hi! My name is: <%= model.FirstName %><%= model.LastName %></h2>
I like:
<ul>
<% model.Hobbies.each do |hobby|
render_li hobby
end %>
</ul>
<pre>
<%= encode model.UglyJavaScript %>
</pre>
</body>
</html>
In order to present a usage of custom IronRuby function added to the template, below you can find extended model from previous example. Now the model contains additional property named UglyJavaScript containing JavaScript code which should be encoded before it can be presented in HTML.
var model = new SampleModel
{
FirstName = "Marcin",
LastName = "Obel",
Hobbies = new List<string>
{
"yachting",
"fishing",
"cycling"
},
UglyJavaScript = @"<script type='text/javascript'>window.close();</script>"
};
var result = new RhtmlEngine().Render(model, "AdvancedTemplate.rhtml", "AdvancedHtml.html");
Like in previous example after passing the model and the template into engine we receive an HTML. This time as you can see it contains JavaScript code from model encoded using .NET Framework functionality in order to be able to display it.
<html>
<body>
<h1>Hi! My name is: MarcinObel</h2>
I like:
<ul>
<li>yachting</li><li>fishing</li><li>cycling</li>
</ul>
<pre>
<script type='text/javascript'>window.close();</script>
</pre>
</body>
</html>
Resources
Fluent NHibernate conventions – examples
Posted by – November 26, 2009
Fluent NHibernate is my favorite extension for NHibernate. I am using it since early betas and I have to say that I love it. One of its underestimated features are conventions. I decided to extract some of them from one of my projects and provide real life examples how they can be used. My conventions are listed below but if you need more information visit Fluent NHibernate Wiki where this feature is described in detail.
ColumnNullabilityConvention – says that if nullability for column has not been specified explicitly, should be set to “NOT NULL”.
public class ColumnNullabilityConvention
: IPropertyConvention, IPropertyConventionAcceptance
{
public void Accept(IAcceptanceCriteria<IPropertyInspector> criteria)
{
criteria.Expect(x => x.Nullable, Is.Not.Set);
}
public void Apply(IPropertyInstance instance)
{
instance.Not.Nullable();
}
}
CreatedAtPropertyAccessConvention – says that every property named CreatedAt should be accessed through camel case field hidden behind it.
public class CreatedAtPropertyAccessConvention
: IPropertyConvention, IPropertyConventionAcceptance
{
public void Accept(IAcceptanceCriteria<IPropertyInspector> criteria)
{
criteria.Expect(x => x.Property.Name == "CreatedAt");
}
public void Apply(IPropertyInstance instance)
{
instance.Access.ReadOnlyPropertyThroughCamelCaseField(
CamelCasePrefix.Underscore);
}
}
ForeignKeyConstraintNameConvention – says that name of every foreign key constraint representing one to many relation should consist of names of entities for which it was specified.
public class ForeignKeyConstraintNameConvention
: IHasManyConvention
{
public void Apply(IOneToManyCollectionInstance instance)
{
instance.Key.ForeignKey("{0}_{1}_FK".AsFormat(
instance.Member.Name, instance.EntityType.Name));
}
}
ForeignKeyNameConvention – says that name of every column containing foreign key id should consist of name of type which it points to with “Id” suffix.
public class ForeignKeyNameConvention : IHasManyConvention
{
public void Apply(IOneToManyCollectionInstance instance)
{
instance.Key.Column(instance.EntityType.Name + "Id");
}
}
PrimaryKeyNameConvention - says that name of every column representing primary key should consist of entity name and “Id” suffix.
public class PrimaryKeyNameConvention : IIdConvention
{
public void Apply(IIdentityInstance instance)
{
instance.Column(instance.EntityType.Name + "Id");
}
}
ReferenceConvention – says that name of column referenced in many to one convention should consist of entity name and “Id” suffix.
public class ReferenceConvention : IReferenceConvention
{
public void Apply(IManyToOneInstance instance)
{
instance.Column(instance.Property.PropertyType.Name + "Id");
}
}
StringColumnLengthConvention – says that if length for string column has not been specified, it should be set to 100.
public class StringColumnLengthConvention
: IPropertyConvention, IPropertyConventionAcceptance
{
public void Accept(IAcceptanceCriteria<IPropertyInspector> criteria)
{
criteria.Expect(x => x.Type == typeof(string))
.Expect(x => x.Length == 0);
}
public void Apply(IPropertyInstance instance)
{
instance.Length(100);
}
}
TableNameConvention – says that if name for table has not been specified, it should be created using concatenation of entity name and “s” suffix.
public class TableNameConvention
: IClassConvention, IClassConventionAcceptance
{
public void Accept(IAcceptanceCriteria<IClassInspector> criteria)
{
criteria.Expect(x => x.TableName, Is.Not.Set);
}
public void Apply(IClassInstance instance)
{
instance.Table(instance.EntityType.Name + "s");
}
}
At the end the most important thing which shows that such conventions make sense. With default Fluent NHibernate conventions DDL generated by NHibernate for MySQL looked like this:
alter table `Athlete` drop foreign key FK9221C9B94070A6F0
drop table if exists Countries
drop table if exists `Athlete`
create table Countries (
Id INTEGER NOT NULL AUTO_INCREMENT,
Name VARCHAR(255),
primary key (Id)
)
create table `Athlete` (
Id INTEGER NOT NULL AUTO_INCREMENT,
DisplayName VARCHAR(255),
Email VARCHAR(255),
Password VARCHAR(255),
CreatedAt DATETIME,
IsActive TINYINT(1),
Country_id INTEGER,
primary key (Id)
)
alter table `Athlete`
add index (Country_id),
add constraint FK9221C9B94070A6F0
foreign key (Country_id)
references Countries (Id)
When I have applied conventions mentioned above to my fluent mappings DDL looks like this:
alter table Athletes drop foreign key Athletes_Country_FK
drop table if exists Athletes
drop table if exists Countries
create table Athletes (
AthleteId INTEGER NOT NULL AUTO_INCREMENT,
DisplayName VARCHAR(100) not null,
Email VARCHAR(100) not null,
Password VARCHAR(100) not null,
CreatedAt DATETIME not null,
IsActive TINYINT(1) not null,
CountryId INTEGER,
primary key (AthleteId)
)
create table Countries (
CountryId INTEGER NOT NULL AUTO_INCREMENT,
Name VARCHAR(100) not null,
primary key (CountryId)
)
alter table Athletes
add index (CountryId),
add constraint Athletes_Country_FK
foreign key (CountryId)
references Countries (CountryId)
For me it looks much better. Additionally I have made it once and that is it. Now I have to care only about domain model and business logic without thinking about not so important stuff lake names of database objects.
MSpec BDD framework installer
Posted by – November 23, 2009
Installation of MSpec BDD framework from source code is quite annoying. With each release you have to deploy everything manually one more time what in fact is hard to accept in 21th century. I know that work on Open Source project requires a lot of time (I have my own project called ByteCarrot) and you cannot do everything. Because of that I decided to help a little bit creators of MSpec and I have prepared an installer for this BDD framework. It is based on WiX and latest release of MSpec witch is version 0.3.
The installer is able to automatically integrate MSpec with TestDriven.NET and ReSharper (4.1, 4.5, 5.0). This is first version of the installer and of course like always there can be some bugs so please let me know if you find something.
Download installer for MSpec 0.3
Rake in .NET projects – installation and setup
Posted by – November 18, 2009
Recently I have rewritten all MSBuild scripts which I used in ByteCarrot project to Rake. I made the decision about changing build solution mostly because I required something what works not only under Windows but also on other operating systems. After rewriting turned out that Rake is a great solution for tasks for which it was created and can be used not only with Ruby/RoR projects but also with other technologies like .NET and Mono. It is really awesome multi-purpose tool. Today I would like to show you how to install and configure Rake on Windows operating system in order to start using it in your projects.
Ruby installation
First of all, because Rake is based on Ruby language, you will need an interpreter. You can download Ruby distribution from its official website but I do not recommend that because there is only installer for version 1.8.6 which is quite old. Other packages for Windows on this website are in a form of compressed archives and do not contain some additional, required libraries. In my opinion the best option is to download one of preview version of installer for Ruby 1.9.1-p129 (rubyinstaller-1.9.1-p129-preview1.exe) available on RubyForge.
When the installer is on your hard drive, start installation. There is nothing magic in the installation process but you should remember that Rake does not work properly when Ruby in installed in C:\Program Files directory (probably because of space in the path). Because of that leave the default installation path or change it to something without spaces like for example C:\Ruby.
Last thing you should do to be able to use Ruby is adding the location of its binaries to the %Path% environment variable. In my case this variable was extended with C:\Ruby\bin path.
Now you can check if everything works by executing from command line two following commands:
ruby –v gem -v
The output from console should be:
C:\>ruby –v ruby 1.9.1p129 (2009-05-12 revision 23412) [i386-mingw32] C:\>gem –v 1.3.4
Rake installation
Now, when Ruby is installed and you are sure that it works you can take care of Rake. The most popular and safe way to install Ruby extensions and libraries (including Rake) is mechanism called Gems. In order to install Rake using Gems execute following command from command line:
C:\>gem install --remote rake
The output from console should be:
C:\>gem install --remote rake Successfully installed rake-0.8.7 1 gem installed Installing ri documentation for rake-0.8.7... Updating class cache with 0 classes... Installing RDoc documentation for rake-0.8.7...
When the command will finish do not close command line window yet. At the end execute one more command to be sure that Rake is installed properly:
C:\>rake –V
The output from console should be:
C:\>rake –V rake, version 0.8.3
Congratulations! You have managed to install Rake and you are ready to write your first build script. More about Rake can be found on official site of the project. Example Rake scripts can be found in ByteCarrot source code on CodePlex.
ASP.NET MVC 2 Beta – new features
Posted by – November 18, 2009
Yesterday at PDC 09 Bob Muglia announced the release of ASP.NET MVC 2 Beta. This release contains a lot of new, interesting stuff. Below you can find a list of new features taken from official release notes.
New RenderAction method
Html.RenderAction (and its counterpart Html.Action) is an HTML helper method that calls into an action method from within a view and renders the output of the action method in place. Html.RenderAction writes directly to the response, whereas Html.Action returns a string with the output. RenderAction works only with actions that render views.
Strongly typed UI helpers
ASP.NET MVC 2 includes new expression-based versions of existing HTML helper methods. The new helpers include the following:
- ValidationMessageFor
- TextAreaFor
- TextBoxFor
- HiddenFor
- DropDownListFor
TempDataDictionary improvements
The behavior of the TempDataDictionary class has been changed slightly to address scenarios where temp data was either removed prematurely or persisted longer than necessary. For example, in cases where temp data was read in the same request in which it was set, the temp data was persisting for the next request even though the intent was to remove it. In other cases, temp data was not persisted across multiple consecutive redirects.
To address these scenarios, the TempDataDictionary class was changed so that all the keys survive indefinitely until the key is read from the TempDataDictionary object. The Keep method was added to TempDataDictionary to let you indicate that the value should not be removed after reading. The RedirectToActionResult is an example where the Keep method is called in order to retain all the keys for the next request.
Client validation library
MicrosoftMvcAjax.js now includes a client-side validation library that is used to provide client validation for models in ASP.NET MVC. To enable client validation, include the following two scripts in your view.
- MicrosoftAjax.js
- MicrosoftMvcAjax.js
The following example shows a view with client validation enabled.
<script type="text/javascript" src="MicrosoftAjax.js"></script>
<script type="text/javascript" src="MicrosoftMvcAjax.js"></script>
<% Html.EnableClientValidation(); %>
<% using(Html.BeginForm()) { %>
//...
<% } %>
“Add Area” dialog box
ASP.NET MVC 2 Beta includes a new Add Area context menu item when you right-click either the root project node or the Areas folder (if one exists). If a root Areas folder does not already exist, the command creates one, and it then creates the files and folders for the area that you specify.
Calling action methods asynchronously
The AsyncController class is a base class for controllers that enables action methods to be called asynchronously. This lets an action method call external services such as a Web service without blocking the current thread. For more information, see Using an Asynchronous Controller in ASP.NET MVC In the ASP.NET MVC 2 documentation.
Blank project template
In response to customer feedback, an empty ASP.NET MVC project template is now included with ASP.NET MVC 2 Beta. This empty project template contains a minimal set of files used to build a new ASP.NET MVC project.
Multiple model validator providers
ASP.NET MVC 2 Beta lets you register multiple validation providers. The following example shows how to register multiple providers.
protected void Application_Start() {
ModelValidatorProviders.Providers.Add(new MyXmlModelValidatorProvider());
ModelValidatorProviders.Providers.Add(new MyDbModelValidatorProvider());
//...
}
Multiple value provider registration
In ASP.NET MVC 2 Beta, the single value provider that was available in ASP.NET MVC 1.0 has been split into multiple value providers, one for each source of request data. The new value providers include the following:
- FormValueProvider
- RouteDataValueProvider
- QueryStringValueProvider
- HttpFileCollectionValueProvider
These value providers are registered by default. You can register additional value providers that pull data from other sources. The following example shows how to register additional value providers in the in Global.asax file.
protected void Application_Start() {
ValueProviders.Providers.Add(new JsonValueProvider());
//...
}
Metadata based validation with jQuery
Posted by – October 8, 2009
Recently I spent some time prototyping my own validation for ASP.NET MVC. Why did not I reuse any of existing solutions? This is a story for another post so I did not want to bring this topic up now. One of the things which I had to figure out during prototyping was how to implement client side validation. Of course I wanted to utilize capabilities of some well known JavaScript framework (no I am not so crazy to write it for my own). I made small evaluation comparing available options and at the end I decided to incorporate jQuery and its Validation plugin. One of the things which were crucial to my decision was ability of this framework to use metadata stored as JSON in class attribute of HTML element. The concept of metadata available in jQuery is amazing and gives possibility to describe validation rules for specified input control inside itself. In my case this was very important feature because I wanted to render validation using my custom HtmlHelper extensions together with corresponding input controls. Second thing which convinced me to jQuery Validation was easy setup which I want to show you now.
If you want to use jQuery Validation in your project first of all you will need of course jQuery library which can be downloaded here, jQuery Metadata plugin which is available here and jQuery Validation plugin downloadable from here.
When you collected all required prerequisites you have to add reference to them in your HTML. Simply add code shown below to the body of tag but remember to ensure that paths lead to place where JavaScript files are located.
<script type="text/javascript" src="jquery-1.3.2.min.js"></script> <script type="text/javascript" src="jquery.validate.min.js"></script> <script type="text/javascript" src="jquery.metadata.js"></script>
When jQuery libraries are already where they should be you can specify validation rules using metadata. In order to do it extend your input control tag with class attribute and set its value to {required:true}. This will tell Validation plugin that this specified input control should contain a value before it can be send back to server. Of course this is very simple rule but below I have listed few more, complex definitions.
<input class="{required:true, maxlength:100, messages:{required:'This field is required.', maxlength:'This field can contain maximum 100 characters.'}}" />
<input class="{maxlength:50, email:true, equalTo:'#Email', messages:{required:'This field is required.', maxlength:'This field can contain maximum 100 characters.', email:'This is not a valid email.', equalTo:'Value entered in this field should equal to value of Email field.'}}" />
Listing below shows this validation metadata in wider context.
<form id="MyForm" method="post" action="/Registration">
<label for="DisplayName">Username:</label>
<input id="DisplayName" class="{required:true, maxlength:100, messages:{required:'This field is required.', maxlength:'This field can contain maximum 100 characters.'}}" type="text" name="DisplayName" />
<input value="Submit!" type="submit" />
</form>
At the end when you have defined all validation rules only thing you should do is adding following code after closing tag and that is it.
<script type="text/javascript">
$("#MyForm").validate({
errorElement: "span"
});
</script>
Now when you will click Submit! button your form will be validated and in case of errors apropriate messages will be displayed below corresponding input control.
Because I know that described example can be not enough to fully understand how all it works I have prepared more complex, example form which can be downloaded from here: download.
My favorite System.String extension methods
Posted by – September 27, 2009
Each business applications developer spends a lot of the time working with strings. Strings are everywhere and we do not avoid that, but we can make our life simpler. How many times each day do you use String.Format(), String.Trim() or String.IsNullOrEmpty()? This are of course very helpful method but turned out that in my case they do not provide a functionality I require. I found out that almost all the time I am treating null, an empty string and a string with whitespaces only as the same “undefined/unkown” value. I am doing that mostly with strings received from outside of my applications where I an interested in “real values” instead of for instance a string with spaces only. In this case, methods mentioned above do not meet my needs. Because of that I have created replacement for them as an extension methods and they became my favorite tools to work with strings (I am using them everywhere instead of out of the box methods).
StringExtensions class defining extension methods:
using System;
namespace ByteCarrot.Shared.Infrastructure
{
public static class StringExtensions
{
public static string NullTrim(this string s)
{
if (s == null)
{
return null;
}
s = s.Trim();
return s == String.Empty ? null : s;
}
public static bool IsSet(this string s)
{
return s.NullTrim() != null;
}
public static string AsFormat(
this string s, params object[] args)
{
return String.Format(s, args);
}
}
}
IsSet() extension method – returns true only if string contains at least one “printable” character:
if (!this.Commands.IsSet())
{
this.Logger.LogError("Commands not specified.");
}
NullTrim() extension method – returns string trimmed from both sides and null when base string was null or after trimming turned out that output is an empty string:
var commands = this.Commands.NullTrim();
AsFormat() extension method – shorter replacement for System.String:
Resources.RequiredField.AsFormat("First name");
It is nothing fancy but make my life easier.
ReSharper’s Live Templates for MSpec BDD framework
Posted by – September 23, 2009
Few days ago Pawel Lesnikowski has blogged about his Live Templates for ReSharper. Because I think it is good idea to share such things with other developers I decided to show my Live Templates I have made to be able to create BDD specifications with MSpec faster. Here they are:
specc – Short template for MSpec BDD context
public abstract class with_$Context$
{
Establish context = () =>
{
$END$
};
}
specf – Full template for MSpec BDD specification
[Subject(typeof($Subject$))]
public class when_$Specification$
{
Establish context = () =>
{
};
Because of = () =>
{
};
It should_$Behaviour$;$END$
}
specs – Short template for MSpec BDD specification
[Subject(typeof($Subject$))]
public class when_$Specification$
{
It should_$Behaviour$;$END$
}
spect – Default template for MSpec BDD specification
[Subject(typeof($Subject$))]
public class when_$Specification$ : with_$Context$
{
Because of = () =>
{
};
It should_$Behaviour$;$END$
}
Here you can download definition of all mentioned templates which can be imported to your ReSharper: MSpec.LiveTemplates
ASP.NET MVC in a corporation – part #2
Posted by – September 10, 2009
In my previous post I have mentioned that I am currently evaluating the ASP.NET MVC in context of usage for building internal corporate applications. During the evaluation I have made my small SWOT analysis and I want to share it with you in order to get to know what your opinion on this topic is. Because my all thoughts reside in a mind map I have dumped them to the plain list:
Strengths:
- It is based on the Convention over Configuration principle, what means less ceremony in code and more time to focus on business rules;
- It is highly extensible with many points of extension in every part of application lifecycle.
- It is highly testable no matter if you are using the TDD or BDD style of unit testing;
- It is provided by Microsoft – big player on the market, what at least in theory guarantee that the solution will be supported for a long time;
- It contains a lot of elements known from classic ASP.NET like notion of session, modules, handlers, HTTP context, views based on ASPX pages and ASCX controls. This is quite important if employees have to switch to the ASP.NET MVC and previously they have used classic ASP.NET, because the learning curve is smaller;
- It does not use the ASP.NET postback and view state models what improves testability and separation between user interface and business logic;
- It has a routing functionality what enables cleaner URLs;
- It gives the full control over all aspects of developed application. Many elements of the ASP.NET MVC can be easily replaced with its custom implementation (i.e. view engine, controller factory);
- It gives the full control over HTML and how views are rendered;
- It has a great AJAX and JSON support so usage of JavaScript frameworks like jQuery is trivial;
- It can be easily integrated with any of popular Inversion of Control frameworks;
- It has quite big community, there is a lot of online documentation and books;
Weaknesses:
- It is based on the Convention over Configuration principle, what means more magic working in a background (probably harder debugging in some cases);
- It is not event driven, so can be difficult for people who know only ASP.NET Web Forms to wrap their minds around it;
- Third party libraries support is not that strong. Not to many companies write extensions for this framework what means more work for internal team;
- Current version (1.0) requires some additional effort to reduce usage of magic strings to the minimum;
Opportunities:
- Allows for Test Driven Development – it is build with TDD in mind, so it is much easier to write unit tests, mock objects and to intercept the program flow;
Threats:
- Bigger ramp-up and training time is required for developers with no or little experience in web application development;
For the time being this is all what came up to my mind. If you have some other thought I will be grateful if you will share them with me.
