Integrating dot less css is pretty easy by default, as shown on its home page however I wanted something that could be configured by application users. We want to be able to specify the link html tag like the following.

<link href="/public/css/sites.less" rel="stylesheet" type="text/css" />

There are few steps involved in the solution I have come up with so bare with me as I go through them. Firstly we’ll start with the web.config:

        <compilation>
            <buildProviders>
                <add extension=".lessx" type="System.Web.Compilation.PageBuildProvider" />
            </buildProviders>
        </compilation>

Insert the builderProviders block inside the compilation section. The compilation section will be under the system.web section. This will enable us to use code blocks in our lessx files.

Secondly, is the routing.

        //Special Route for css so that images are relative to it
        routes.MapRoute("css",
                           "public/css/{filename}.less",
                           new { controller = "Css", action = "Index” },
                           new[] { "eLearning.Controllers" });

This specifies that any url matching /public/css/{filename}.less should be routed to the CssController passing the filename as the parameter to the Index method.

    public class CssController : BaseController
    {
        [OutputCache(Duration = 10, VaryByParam = "")]
        public ActionResult Index(string filename)
        {
            if (string.IsNullOrEmpty(filename))
                throw new ArgumentException("A filename must be supplied");

            ViewData["baseColor"] = "#aabbcc";

            var less = RenderViewToString(filename + ".lessx", null);
            var css = LessCss.Generate(less, true);
            return Content(css, "text/css");
        }
    }

    public static class LessCss
    {
        public static string Generate(string less, bool minify)
        {
            var lessEngine = new EngineFactory();
            lessEngine.Configuration.MinifyOutput = minify;
            var output = lessEngine.GetEngine().TransformToCss(less, null);
            return output;
        }
    }

This is the css controller class. It receives the filename as the input, finds the corresponding .lessx file and returns the file with appropriate view data replaced. Is then takes the less formatted string and runs it through the dot less parser to return a css string. This is then returned to the browser with the appropriate content-type. One method I have not shown is the RenderViewToString() and how the .lessx file is located. This method is located on the base controller class that the css controller inherits from. I have also turned Caching on so that it will cache the result for 10seconds.

        protected string RenderViewToString(string viewName, object model)
        {
            if (string.IsNullOrEmpty(viewName))
                viewName = ControllerContext.RouteData.GetRequiredString("action");

            ViewData.Model = model;

            using (StringWriter sw = new StringWriter())
            {
                ViewEngineResult viewResult = ViewEngines.Engines.FindView(ControllerContext, viewName, null);
                ViewContext viewContext = new ViewContext(ControllerContext, viewResult.View, ViewData, TempData, sw);
                viewResult.View.Render(viewContext, sw);

                return sw.GetStringBuilder().ToString();
            }
        }

This method finds the .lessx file and returns the result as a string. Now usually the view engine will take controller name and method name and by convention look in the /Views/css/index.aspx file. It doesn’t quite make sense to put it in the views folder so I have overridden the default web forms view engine so that they can be placed in the /Public/Css folder. This can be configured to your liking (convention).

    public class CustomViewEngine : WebFormViewEngine
    {
        public CustomViewEngine()
        {
            var locs = new List<string>(base.ViewLocationFormats);
            locs.Add("~/Public/{1}/{0}"); //My personal choice
            locs.Add("~/Views/{1}/{0}");  //An alternative choice
            base.ViewLocationFormats = locs.ToArray();
        }
    }

Once your Custom View Engine has been overridden, you will need to add it to the ViewEngines.Engines collection in the application start method in the global.asax.cs.

        ViewEngines.Engines.Clear();
        ViewEngines.Engines.Add(new CustomViewEngine());

This will then allow us to write a *.lessx file like the following; you can also pass a strongly typed model to the .lessx file if you so wish in the same way you would to a regular aspx view.

<%@ Page Language="C#" Inherits="System.Web.Mvc.ViewPage" %>

@basecolor: <%= ViewData["baseColor"] %>;

body {
    background: @basecolor;
}

Which will be rendered to the browser as:

body {
    background: #aabbcc;
}

And that’s it. I’m still working on the finer details but I am liking how it works at the moment. If you have any thoughts or suggestions, please leave a comment.

Adam

Updated: 16th May 2010 after some feedback

Take these two classes for example:

    public class User
    {
        public string Id { get; set; }
        public string Name { get; set; }
        public IList<Role> Roles { get; set; }
    }

    public class Role
    {
        public string Name { get; set; }
        public int AccessLevel { get; set; }
    }

and given the following data:

            var standardRole = new Role {Name = "Standard", AccessLevel = 2};
            var adminRole = new Role { Name = "Standard", AccessLevel = 5 };
            var user1 = new User()
            {
                Id = "jbloggs",
                Name = "Joe Bloggs",
                Roles = new List<Role>
                            {
                                standardRole,
                                adminRole
                            }
            };

            var user2 = new User()
            {
                Id = "tsmith",
                Name = "Tony Smith",
                Roles = new List<Role>
                            {
                                standardRole,
                            }
            };

Now say I want to find all users with access level greater than or equal to 5. In Linq-2-sql or plain sql your might write this query like the following.

var query = list.Where(x => x.Roles.Where(y => y.AccessLevel >= 5).Count() > 0).ToList();

This query will not work in the NoRM linq provider, however there is an alternative.

1. var queryforMongo = list.Where(x => x.Roles[0].AccessLevel >= 5).ToList();or

2. var queryforMongo = list.Where(x => x.Roles.Any(y=>y.AccessLevel >= 5)).ToList();

Query 1 here will only return Users where the first role has an access level greater than or equal to 5.

Query 2 will return Users where 1 of the Roles has an access level greater than or equal to 5.

One caveat though. If you try and do a complex query ( one involving an “or” condition or a “and” using the same property ) then you will get an exception. This is because complex queries get converted to a javascript function that cannot be used in the same ways.

Hope this comes in handy for folks out there.

Adam

It currently supports a lot of functionality including deep queries, regex, datetime which is really exciting. In this post though I am going to concentrate on regular expressions.

This is the newest part of the Linq provider however it is probably the most powerful, especially for complex queries. The reason for this is that MongoDB will use the indexes created when a regular expression is used (where the query is not a complex query). A complex query is one that filters on the same property twice, uses a string function (replace/substring/toLower etc) or does some other fancy stuff. For example using the toUpper() method.

var products = session.Products.Where(x => x.Name.ToUpper() == "TEST3").ToList();

Anyways….i digress. So, here is an example of using a Regex in a Linq Query. Pretty simple.

var products = session.Products.Where(p => Regex.IsMatch(p.Name, "^te")).ToList();

Using the static Regex.IsMatch is the only way to invoke a regex call using the Linq Provider. This will however run blazingly fast. I tested this query on 1,000,000 Products and it only took 1.5sec, which was approximately 10x faster than when a complex query is invoked. There are however 3 string functions that have been optimized using this regex functionality. They are StartsWith(), EndsWith() and Contains() which is why the following query only takes 2secs to return over 48,000 rows, however when using Skip() and Take() you can get 50 results back in just milliseconds.

var products = session.Products.Where(x => x.Name.StartsWith("X")).ToList();

The Linq provider also supports 3 of the RegexOptions. They are RegexOptions.IgnoreCase (but please note this will not use the index so will be slower), RegexOptions.Multiline and RegexOptions.None. Regex’s can also be used in conjunction with other filters. eg.

var products = session.Products.Where(p => Regex.IsMatch(p.Name, "^te") && p.Price == 10).ToList();

This query is not considered a complex query because two different properties are used and an “and”(&&) operator is used.

Please note: Any time a “or” (||) operator is used, it will be considered a complex query.

Summary:

If you have a filter than can be written as a regex, chances are it will be as fast or faster than without using a regex.

So please go and try out NoRM and enjoy the freedom. I will try and post some more cool stuff in the LINQ provider over the next few weeks. Stay tuned.

It currently supports the following FV validatiors:

• NullValidator
• NotEmptyValidator
• LengthValidator
• RegularExpressionValidator
• ComparisonValidator including:
  • Equal
  • Not Equal
  • Greater Than or Equal
  • Less Than or Equal

To configure the integration we need to tell xVal to use the FV rules provider rather than the default one. This is done in the global.asax.cs in Application_Start().

xVal.ActiveRuleProviders.Providers.Clear();
xVal.ActiveRuleProviders.Providers.Add(
    new FluentValidation.xValIntegration.
            FluentValidationRulesProvider(new AttributedValidatorFactory()));

The rules provider here is instructed to use the AttributedValidatorFactory to instruct the provider to use the attribute attached to the model class to find the validation class for that model.

Note: This is still new and xVal is still in beta so there may be some issues. If you find any please let me know so we can fix them as soon as possible.

Hopefully once its ready it can be checked in with the other providers at the xVal codeplex site.

This is currently in the development source code which can be downloaded and tried now.

Cheers,

Adam

Since then I have submitted a few patches for the framework, one of which is the Fluent Validation Model binder. Inspired by the Data Annotations Model binder, it works in much the same way. Once you have it set to your default model binder, it will validate any model which contains the specific attribute. This will become clear in the examples below.

Firstly lets take our model.

    [Validator(typeof(LineItemValidator))]
    public class LineItem
    {
        public int LineNumber { get; set; }
        public DateTime Date { get; set; }
        public string Description { get; set; }
        public decimal Net { get; set; }
        public decimal Tax { get; set; }
        public decimal Gross { get; set; }
    }

Attached to this simple LineItem class is a Validator attribute. This attribute is used by the Model Binder to locate the Class used for validation. Below I will define my LineItemValidator class which will hold the rules for the validation.

    public class LineItemValidator : AbstractValidator<LineItem>
    {
        public LineItemValidator()
        {
            RuleFor(x => x.Description)
                .NotEmpty().When(x => Settings.DescriptionRequired)
                .And
                .Length(0, 30);

            RuleFor(x => x.Date)
                .GreaterThanOrEqualTo(DateTime.Today);

            RuleFor(x => x.Net)
                .GreaterThan(0);

            RuleFor(x => x.Gross)
                .GreaterThan(0)
                .And
                .Equal(y => (y.Net + y.Tax))
                .WithName("Total Amount");
        }
    }

As you can see the class must inherit from AbstractValidator<T> where T is the model you want to define the rules for. The first rule uses the conditional When clause where it will only validate that the field is NotEmpty when the Settings.DescriptionRequired boolean is true. Also, another thing is the complex validation taking place on the Gross field. Not only does it validate that it is greater than 0, but that the value is equal to the net + tax amount. This is very elegant indeed. I have also specified the ‘WithName’ clause which has also been integrated into the model binder so that if an error occurs with the gross field, the WithName value will be displayed when an error happens. This is extremely handy for language localization or when the name of the field on the Model is insufficient.

Wiring this Model binder up in the Application_start event in the global.asax.cs is as easy as this.

     ModelBinders.Binders.DefaultBinder =
                new FluentValidationModelBinder(new AttributedValidatorFactory());

Note that we have to pass an instance of the AttributedValidatoryFactory into the Model Binder. This means if you have an alternate way of locating the Validator class other than via the attribute you can inherit from IValidatorFactory and create your own.

Now when a parameter of LineItem gets passed into a controller it will be validated against the model and all errors placed into the ModelState. This can then check the isValid property to determine if there are any errors and proceed accordingly.

        [AcceptVerbs(HttpVerbs.Post)]
        public ActionResult Edit(List<LineItem> lineItems)
        {
            if (ModelState.IsValid)
                return RedirectToAction("Edit");

            return View();
        }

And that’s it. I hope you enjoy using the Fluent Validation framework as much as I have and happy coding. For all you guys waiting for xVal integration, I will try and post a solution in the coming week.

Adam

The northwind database has a suppliers table. The info contained below is using that table with linq-to-sql.

After adding the table to the designer, a Supplier class gets constructed in the background. This class is a partial class which means we can add to it without changing the code auto-generated in the designer.cs file.

We can then create a partial class called Supplier inheriting from Custom Validation and add a MetadataType attribute to it. This attribute specifies the class for which use for validating the Supplier class.

    [MetadataType(typeof(SupplierValidation))]
    public partial class Supplier : CustomValidation
    {
    }

We can then create the SupplierValidation class specifying the properties of the Supplier class we would like to be validated. For instance here I only want to validate the ContactName and the ContactTitle of the Supplier.

        public class SupplierValidation
    {
        [Required]
        public string ContactName { get; set; }

        [Required, Range(0, 10)]
        public string ContactTitle { get; set; }
    }

This specifies that both fields are required and that the ContactTitle cannot be more than 10 characters in length.

The other benefit of using the buddy class here is that if you need to regenerate a table in the linq-to-sql designer, you won’t lose your changes because they’re contained in a separate file.

From here when a Supplier gets passed to in as a parameter on a Controller action it will be validated using the rules in the Supplier Validation class.

Cheers,

Adam

        var reference_number_old = "$##%@";
        while (recordsExist)
        {
            reference_number = String(rs(0));

            if (reference_number_old != reference_number)
            {
                Response.Write(reference_number);
                reference_number_old = reference_number;
            }

            //Do more stuff
        }

Sooo very very painful, and that’s only grouping by one column (reference number).

Now however with OO programming and the advance of Linq there is a much nicer and easier way to deal with this Master-Detail type one-to-many relationship.

Lets see how we do it now, still using our own custom sql.

Firstly here is our class to represent our flat data straight out of the database.

        public class FlatCustomerAndOrders
        {
            public int ReferenceNumber { get; set; }
            public string Name { get; set; }
            public string Address { get; set; }
            public int OrderId { get; set; }
            public string ProductName { get; set; }
            public string Description { get; set; }
            public decimal Amount { get; set; }
        }

Even filling this class used to be a bit painful before Linq. You would have to create a connection, create a reader, then instantiate the FlatCustomerAndOrders class. Set the properties then add the object to a list while records could still be read. Here’s how I do it now.

        DataContext dc = new DataContext(new SqlConnection(connString));
        IEnumerable<FlatCustomerAndOrders> flat =
            dc.ExecuteQuery<FlatCustomerAndOrders>("select c.referencenumber, c.name," +
            "c.address, o.orderid, o.productname, o.description, o.amount from customers " +
            "c inner join orders o on c.referencenumber = o.referencenumber");

Thats its. We have our List of FlatCustomerAndOrders.

The next step is to organise the data so that the data is nested so its easy to display with just two foreach loops. The two classes:

        public class Customer
        {
            public int ReferenceNumber { get; set; }
            public string Name { get; set; }
            public string Address { get; set; }
            public List<Order> Orders { get; set; }
        }

        public class Order
        {
            public int OrderId { get; set; }
            public string ProductName { get; set; }
            public string Description { get; set; }
            public decimal Amount { get; set; }
        }

To fill these two class we do some clever Linq using the GroupBy method. Here’s the code.

        IList<Customer> Customers =
            flat.GroupBy(cust => new { cust.ReferenceNumber, cust.Name, cust.Address })
                .Select(c => new Customer()
                {
                    ReferenceNumber = c.Key.ReferenceNumber,
                    Name = c.Key.Name,
                    Address = c.Key.Address,
                    Orders = c.Select(o => new Order()
                    {
                        OrderId = o.OrderId,
                        ProductName = o.ProductName,
                        Description = o.Description,
                        Amount = o.Amount
                    }).ToList()
                }).ToList();

And that’s it. It may look like a bit of a mouthful but its quite simple really.

It just takes the flat list and applies the groupby method to it grouping by the three customer columns. It then builds a new list to fill the Orders property with.

Its then super easy to display the data like so.

        foreach (Customer c in Customers)
        {
            //Display the customer details

            foreach (Order o in c.Orders)
            {
                //Display the orders for each customer
            }
        }

Well I hope this helps you as much as it has helped me.

Cheers

Schotime

After managing to get some lines of communication going between the client and server applications, I couldn’t help but notice that it was taking a little bit longer than it probably should have. I decided to have a closer look.

Using some basic timestamping in the console/website application the whole process was taking just over 1 second. This was to connect, send and then receive a response. Further investigation revealed only 1 statement was causing the time to blow out. Below is the statement.

TcpClient socketForServer = new TcpClient("localhost", 200);

Now in all the demos and tutorials this is how it showed to connect to the server. Pretty straightforward and simple. Or so I thought. Whilst having a look through the methods associated with the TcpClient, there was one that stood out: Connect(). Hmmm…this also took a host name and a port. I decided to give it a try.

TcpClient socketForServer = new TcpClient();
socketForServer.Connect("localhost", 200);

I bet you’re wondering right now. What is the difference?? At this point in time I’m not quite sure but I’m determined to figure it out because after making that change the time to execute the previous two statements was about 1 millisecond or so. Much better.

One thing that did seem odd was if the TcpClient failed to make a connection, the response time was almost exactly the same (~1sec).

If anyone knows the reason, please leave a comment. Until then, two lines will have to do.

When I first put the GridView together, I was surprised to find that there was no Value property for the asp:checkbox nor could you bind any other column in a database but a ‘bit’ column to it.

The only solution I could come up with was to create a custom Checkbox and implement the feature. Below is the code for the custom Checkbox.

using System;

using System.ComponentModel;

using System.Web.UI;

using System.Web.UI.WebControls;

namespace ServerControls

{

    [Bindable(true)]

    [Category("Appearance")]

    [DefaultValue("")]

    [Localizable(true)]

    [ToolboxData("<{0}:CheckBoxValue runat=server></{0}:CheckBoxValue>")]

    public class CheckBoxValue : CheckBox

    {

        private string _value;

        private string _unCheckedValue;

        private string _checkedValue;

        public string Value

        {

            get { return _value; }

            set

            {

                _value = value;

                if (value != null && this.CheckedValue != null && this.UnCheckedValue != null)

                    base.Checked = value == this.CheckedValue;

            }

        }

        public string CheckedValue

        {

            get { return _checkedValue; }

            set { _checkedValue = value; }

        }

        public string UnCheckedValue

        {

            get { return _unCheckedValue; }

            set { _unCheckedValue = value; }

        }

        public override bool Checked

        {

            get { return base.Checked; }

            set

            {

                base.Checked = value;

                if (this.Value != null && this.CheckedValue != null && this.UnCheckedValue != null)

                    this.Value = value ? this.CheckedValue : this.UnCheckedValue;

            }

        }

        protected override void OnInit(EventArgs e)

        {

            Page.RegisterRequiresControlState(this);

            base.OnInit(e);

        }

        protected override object SaveControlState()

        {

            object[] state = new object[2];

            state[0] = base.SaveControlState();

            state[1] = this.Value;

            return state;

        }

        protected override void LoadControlState(object state)

        {

            object[] stateTmp = (object[])state;

            base.LoadControlState(stateTmp[0]);

            this.Value = (string)stateTmp[1];

        }

    }

}

The magic in the custom checkbox occurs in the Value property and the overridden Checked property.

When the value property is set, if it is the same as the ‘CheckedValue’ property then we set the base.Checked value to true else false. The same principles apply to the overridden Checked property. When the property is set we set the Value property to the ‘CheckedValue’ property if Checked equals true else we set it to the ‘UnCheckedValue’.

Once compiled we can then use this inside our GridView template and bind a varchar column from a database to it. Here is the syntax.

<Custom:CheckBoxValue
        ID="cbv1"
        runat="server"
        CheckedValue="Y"
        UnCheckedValue="N"
        Value='<%# Bind("valueyn") %>' />

So when the GridView databinds and evaluates the ‘valueyn’ column; if the value is ‘Y’ then the checkbox will be checked and if the value is ‘N’ then the checkbox will be unchecked. Then if I choose to edit a line with the checkbox and change its value, the value stored in the database will match the value of the checkbox. eg. if the checkbox is checked, ‘Y’ will be entered into the database and if it is left unchecked then ‘N’ will be entered.

This seems to work extremely well for my project and suits my needs. It will even work if the ‘valueyn’ column is an Int, as long as you modify the ‘CheckedValue’ and ‘UnCheckedValue’ to something that can be implicitly converted to an Int.

Hope this helps. If you find any issues or have other ideas please don’t hesitate to leave a comment.

There are many situations where you need to read data from a file into memory or a database. Lets consider this scenario.

We have a tab delimited data file that has been exported from some web or windows application etc. Below is the sample file.

carrots    4    0.64
beans      3    0.12
oranges    7    1.02
apples     5    0.87

This file includes three columns. Column 1is the name of the product. Column 2 is the quantity and Column 3 is the unit price. We would also like a total price column derived from column 2 being multiplied by column 3.

Our aim here is to load these into our application programmatically and then bind them to a gridview. Normally you would have to read the file in line by line then do a split on each line, enter each line into a prebuilt class or datatable then add a new column and multiply the quantity by the price to obtain the total. However by using a nice little extension helper method, all of this can be rolled into just a few lines of code.

public static IEnumerable<string> ReadLinesFromFile(string filename)
{
    using (StreamReader reader = new StreamReader(filename))
    {
        while (true)
        {
            string s = reader.ReadLine();
            if (s == null)
                break;
            yield return s;
        }
    }
}

Above is the extension method to convert lines of a file into a IEnumerable list of strings.

var products = from line in ReadLinesFromFile(@"c:\import.txt")
               let item = line.Split('\t')
               select new
               {
                   Product = item[0],
                   Quantity = Convert.ToInt32(item[1]),
                   Price = Convert.ToDecimal(item[2]),
                   Total = Convert.ToInt32(item[1]) * Convert.ToDecimal(item[2])
               };

GridView1.DataSource = products;
GridView1.DataBind();

What this gives us is a list of products, with each one having 4 properties associated with it. We can then bind this straight to a gridview by setting the datasource of the gridview to products and calling the DataBind() method. This will display a table with 4 columns with the headers Product, Quantity, Price and Total.

The Linq statement can then be modified in many ways to accommodate different file formats (eg. CSV or fixed width) with a few simple changes.

This is just another way Linq is making things easier!

Schotime