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Passing Anonymous Types with Dynamic Lists October 1, 2013

Posted by codinglifestyle in C#, CodeProject, Javascript.
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Recently I was rewriting a function with a large method signature which took several arrays as parameters.  As you might guess, the index across these arrays was assumed to be the same which is error-prone.  I thought we should really encapsulate all this information in to a class or struct and pass in a single list instead.  Then I stopped myself as there was no use for this class beyond this one-time call to another function.

Then I thought, I know, I could use an anonymous type instead.

var datum = new { a = myData.a, b = myData.b, /* c, d, ..., */ z = myData.z };

This seems like a reasonable approach and exactly what throw-away anonymous types are for.  Then I tried to add this to a list.  Hmm, with a little creativity I was able to overcome this… except it only worked within the scope of the same function.  Well, I could have passed a list of objects, but what would I cast them to?

I really thought I’d have to cave in and just create the new class but then there was one option I hadn’t considered: dynamic.  Like JavaScript, this frees you from the restriction of static typing which was inhibiting a simple notion to pass a list of anonymous types to another function.  Now our list definition looks like this:

var data = new List<dynamic>();

Now this means I could really add in anything and its evaluation will be resolved at runtime.  So we’re finally free to use our anonymous class however we want.  We could even code access to properties which we aren’t supplying and code will compile (however you’ll get a nasty surprise at runtime).

protected void Bob()
{
    List<dynamic> data = new List<dynamic>();

    //
    //Assume lots of processing to build up all these arguments
    //
    data.Add(new { a = 1, b = "test" });

    Fred(data);
}

private void Fred(List<dynamic> data)
{
    //Fred processing logic
    foreach (var datum in data)
    {
        Trace.WriteLine(String.Format("{0}: {1}", datum.a, datum.b));
    }
}

The more evolved my client coding becomes the more restraining statically typed languages can feel.  With the dynamic keyword C# is one step ahead of me allowing a future of amazing code determined by an unlimited number of factors at runtime.

ScriptArguments: An easy way to programmatically pass arguments to script from codebehind January 13, 2012

Posted by codinglifestyle in AJAX, ASP.NET, C#, CodeProject, Javascript.
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During my on-going adventures AJAXifying a crusty old business app I have been using a methodology by which most client events are setup in codebehind. The reason for this is I have easy access to my client ids, variables, and resources in codebehind. By constructing the script function calls at this stage, I can avoid messy and fragile in-line code. What I am endeavouring to do is remove all script from the markup itself. So instead of having MyPage.aspx with script mixed with markup I have MyPage.js and all functions here. Separate js files avoid fragile in-line code which only fails at runtime, can’t be refactored, and doesn’t play as nice with the debugger. Besides, separation of markup and script is good!

The downside to setting up all this script in the codebehind is it didn’t take long for the number of arguments to grow and become unruly. My script function signature looked like this:

function fnAddressChange(ddId, labelId, checkId, sameAsId, hidSelectId, hidSameAsId, onSelectEvent)

And in the codebehind I had this:

string selectArgs     = string.Format("'{0}', '{1}', '{2}', '{3}', '{4}', '{5}'", _DropDownAddress.ClientID, _LabelAddress.ClientID, _RowSameAs.ChildClientID, (SameAs && _SameAsAddress != null) ? _SameAsAddress.LabelControl.ClientID : "-1", _HiddenSelectedID.ClientID, _HiddenSameAs.ClientID);

string selectScript   = string.Format("fnAddressSelect({0}); ", selectArgs);
string changeScript   = string.Format("fnAddressChange({0}, '{1}'); ", selectArgs, OnClientSelect);

We can see selectArgs is getting out of control. Not only is it getting ridiculous to add more to it, the function signature in script is getting huge and the ordering is easier to mess up. So I came up with this solution:

ScriptArguments args = new ScriptArguments ();
args.Add("ddId", _DropDownAddress.ClientID);
args.Add("labelId", _LabelAddress.ClientID);
args.Add("checkId", _RowSameAs.ChildClientID);
args.Add("sameAsId", (SameAs && _SameAsAddress != null) ? _SameAsAddress.LabelControl.ClientID : "-1");
args.Add("hidSelectId", _HiddenSelectedID.ClientID);
args.Add("hidSameAsId", _HiddenSameAs.ClientID);

Not only is the codebehind cleaner but I don’t have to worry about string.Format or the order in which I add arguments in. The resulting script generated is:

args.ToString()
"{ ddId : 'ctl00__ContentMain__ControlOrderSoldTo__AddressSoldTo__DropDownAddress', labelId : 'ctl00__ContentMain__ControlOrderSoldTo__AddressSoldTo__LabelAddress', checkId : 'ctl00__ContentMain__ControlOrderSoldTo__AddressSoldTo__RowSameAs_FormField_CheckBox', sameAsId : '-1', hidSelectId : 'ctl00__ContentMain__ControlOrderSoldTo__AddressSoldTo__HiddenSelectedID', hidSameAsId : 'ctl00__ContentMain__ControlOrderSoldTo__AddressSoldTo__HiddenSameAs' }"

This is a javascript Object with a property per key set to the corresponding value. So in script I only need to take in one argument, the argument object. I can then access every piece of information inserted in to ScriptArguments via the correct key:

function fnAddressIsReadOnly(args) {
     alert(args.ddId);
     alert(args.labelId);
}

Will alert me with “ctl00__ContentMain__ControlOrderSoldTo__AddressSoldTo__DropDownAddress” and “ctl00__ContentMain__ControlOrderSoldTo__AddressSoldTo__LabelAddress”.

The great thing is how simple this was to implement:

public class ScriptArguments : Dictionary<string, string>
{
    public override string ToString()
    {
        StringBuilder script = new StringBuilder("{ ");
        this.Keys.ToList().ForEach(key => script.AppendFormat("{0} : '{1}', ", key, this[key]));
        script.Remove(script.Length - 2, 2);
        script.Append(" }");
        return script.ToString();
    }
}

This simple class solves a simple problem. I hope you find it useful.

Pass a Name Value Pair Collection to JavaScript August 8, 2011

Posted by codinglifestyle in ASP.NET, CodeProject, Javascript.
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In my crusade against in-line code I am endevouring to clean up the script hell in my current project. My javascript is littered these types of statements:

var hid = <%=hidSelectedItems.ClientId%>;
var msg = <%=GetResourceString('lblTooManyItems')%>;

Part of the cleanup is to minimize script on the page and instead use a separate .js file. This encourages me to write static functions which take in ids and resources as parameters, allows for easier script debugging, and removes all in-line code making maintenance or future refactoring easier.

While moving code to a proper .js file is nice there are times we might miss the in-line goodness. Never fear, we can build a JavaScript object containing properties for anything we might need with ease. This equates to passing a name/value pair collection to the JavaScript from the code behind. Take a look at this example:

    ScriptOptions options = new ScriptOptions();
    options.Add("ok", GetResourceString("btnOK"));
    options.Add("oksave", GetResourceString("btnOkSave"));
    options.Add("cancel", GetResourceString("btnCancel"));
    options.Add("viewTitle", GetResourceString("lblAddressEditorView"));
    options.Add("editTitle", GetResourceString("lblAddressEditorEdit"));
    options.Add("createTitle", GetResourceString("lblAddressEditorCreate"));
    options.RegisterOptionsScript(this, "_OptionsAddressEditorResources");

Here we’re using the ScriptOptions class to create an object called _OptionsAddressEditorResources we can access in our script. Now let’s see these options in use:

function fnAddressEditDialog(address, args) {
    //Define the buttons and events
    var buttonList = {};
    buttonList[_OptionsAddressEditorResources.ok]     = function() { return fnAddressEditOnOk(jQuery(this), args); };
    buttonList[_OptionsAddressEditorResources.oksave] = function() { return fnAddressEditOnOkSave(jQuery(this), args); };
    buttonList[_OptionsAddressEditorResources.cancel] = function() { jQuery(this).dialog("close"); };

    //Display the dialog
    jQuery("#addressEditorDialog").dialog({
        title: _OptionsAddressEditorResources.editTitle,
        modal: true,
        width: 535,
        resizable: false,
        buttons: buttonList
    });
}

Above we see the jQuery dialog using the resources contained within the _OptionsAddressEditorResources object.

So this seems simple but pretty powerful. Below is the ScriptOptions class which simply extends a Dictionary and writes out the script creating a named global object. Good luck cleaning up your script hell. Hopefully this will help.

    /// <summary>
    /// Class for generating javascript option arrays
    /// </summary>
    public class ScriptOptions : Dictionary<string, string>
    {
        /// <summary>
        /// Adds the control id to the options script
        /// </summary>
        /// <param name="control">The control.</param>
        public void AddControlId(WebControl control)
        {
            this.Add(control.ID, control.ClientID);
        }

        /// <summary>
        /// Registers all the key/values as an options script for access in the client.
        /// </summary>
        /// <param name="page">The page</param>
        /// <param name="optionsName">Name of the options object</param>
        public void RegisterOptionsScript(Page page, string optionsName)
        {
            if (!page.ClientScript.IsStartupScriptRegistered(page.GetType(), optionsName))
            {
                StringBuilder script = new StringBuilder(string.Format("var {0} = new Object();", optionsName));
                this.Keys.ToList().ForEach(key => script.Append(string.Format("{0}.{1}='{2}';", optionsName, key, this[key])));
                page.ClientScript.RegisterStartupScript(page.GetType(), optionsName, script.ToString(), true);
            } 
        }
    }

OnClientClick Breaks Validation August 20, 2009

Posted by codinglifestyle in ASP.NET, Javascript.
1 comment so far

It’s a horrible sinking feeling when you make a sizable change and everything goes tits up.  I was updating an ASP.NET form the other day which had a lot of HTML controls on it.  I decided to update these to ASP.NET controls and replaced a number of buttons.  While doing this I cleaned up the onclick code, which I placed in OnClientClick.  Unwittingly I managed to break validation for the entire page, as just about every button used this attribute.  I won’t bore you with the details, but suffice it to say I had a few red herrings and couldn’t understand why my page’s validators suddenly stopped working.  I spent all night fretting about it, but this morning the first thing I did was drop a new button on the page, load it up, and click it.  Presto, validation worked for that button but not the other buttons on the page.  What’s going on?

<asp:Button runat=”server” ID=”Save” OnClientClick=”return confirm(‘Are you sure?’);” /> 

 It becomes crystal clear when you view the source of the page.  We will see something like this:

onclick=”return confirm(‘Are you sure?’);WebForm_DoPostBackWithOptions(…)”

It is now clear that we are returning before the validator’s script has a chance to run.  I will pause now for an, “Ohhhhhhh….  <slap to head>”.

Typically, we want to stop execution if our called function returns false but continue if it returns true.  Solving this problem requires just a small change to our script.  Take a look below:

onclick=”if (!confirm(‘Are you sure?’)) return false; WebForm_DoPostBackWithOptions(…)”

Now we will only return false if our script returns false.  If our script returns true, the browser will continue to call WebForm_DoPostBackWithOptions(…) which will execute our validators.

ref: http://vaultofthoughts.net/OnClientClickBreaksValidation.aspx

Currency TextBox with Javascript April 24, 2009

Posted by codinglifestyle in Javascript.
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1 comment so far

This took me a long time so here it is for prosperity.  I started by looking at Ajax’s masked edit field in order to enforce a simply currency field.  This was a waste of time and not up for the job.  I accomplished it with javascript instead.  Very simple, no symbols, just #####.## with the cents being optional. 

Here is the script:

/*

**  Returns the caret (cursor) position of the specified text field.

**  Return value range is 0-oField.length.

*/

function doGetCaretPosition(oField) {

 

    // Initialize

    var iCaretPos = 0;

 

    // IE Support

    if (document.selection) {

 

        // Set focus on the element

        oField.focus();

 

        // To get cursor position, get empty selection range

        var oSel = document.selection.createRange();

 

        // Move selection start to 0 position

        oSel.moveStart(‘character’, -oField.value.length);

 

        // The caret position is selection length

        iCaretPos = oSel.text.length;

    }

 

    // Firefox support

    else if (oField.selectionStart || oField.selectionStart == ‘0’)

        iCaretPos = oField.selectionStart;

 

    // Return results

    return (iCaretPos);

}

 

function fnCurrencyOnly(o) {

    var sValue = o.value;

    var sKey = String.fromCharCode(window.event.keyCode);

    var range = document.selection.createRange();

    var pos = doGetCaretPosition(o);

 

    if (range.text == sValue) {

        sValue = sKey;

    } else {

        sValue = sValue.substr(0, pos) + sKey + sValue.substr(pos);

    }

    var re = new RegExp(“^\\d+(?:(\\.|\\,)\\d{0,2})?$”);

    if (!sValue.match(re))

        window.event.returnValue = false;

}

 

    <div>

        <input type=”text” onkeypress=”fnCurrencyOnly(this);” />

    </div>

 

I’m sure sure who the original author is, but I found the script for doGetCaretPosition() here: http://blog.vishalon.net/index.php/javascript-getting-and-setting-caret-position-in-textarea/

Enjoy!

Cascading Dropdown Lists with jQuery (parent / child select options) March 9, 2009

Posted by codinglifestyle in ASP.NET, C#, CodeProject, Javascript, jQuery.
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Recently I was tasked with merging 3 similar screens in to one.  I took stock of the commonalities and decided a Category and Subcategory dropdown list would suffice.   As you’d expect the contents of the Subcategory dropdown depend on the selected Category.  Obviously I wanted to avoid postbacks so I first looked to the Ajax Control Toolkit’s CascadingDropDown extender to link the parent to the child.  In my case, there were only a dozen subcategories so a webservice seemed like overkill.

After attending Tech-Ed 2008 and seeing Microsoft throwing its weight behind jQuery I decided to have a look.  So what follows is my first foray in to jQuery and I’m quite pleased with the results.

First, we define an enum in the codebehind which can be used for bitwise operations.

public enum Category

{

Invoice     = 1,

Order       = 2,

Shipment    = 4   //Fourth item would be 8, then 16, 32, …

}

Next I wanted to be able to use the enum to specify the Category (only specifying one) and Subcategory items (bitwise OR any combination).

_DropDownCategory.Items.Add(GenerateListItem(“Orders”, Category.Order, false));

_DropDownCategory.Items.Add(GenerateListItem(“Invoices”, Category.Invoice, false));

_DropDownCategory.Items.Add(GenerateListItem(“Shipments”, Category.Shipment, false));

_DropDownSubcategory.Items.Add(GenerateListItem(“Purchase Orders”, Category.Invoice | Category.Order | Category.Shipment, false));

_DropDownSubcategory.Items.Add(GenerateListItem(“Quote Number”, Category.Order, false));

_DropDownSubcategory.Items.Add(GenerateListItem(“Customer Project Number”, Category.Shipment, true));

The enum was converted to a number and added as a custom attribute to the new list item in GenerateListItem():

li.Attributes.Add(“Category”, ((int)eCat).ToString());

Enter jQuery, first we’re going to need to keep a copy of all the available Subcategory items.  Each time we change the Category we will be showing a subset of this array which we must keep separate in memory.

var optSubCat = null;

$(function() {

//Make a copy in memory of all the subcat options

optSubCat = $(“#_DropDownSubcategory”).children().clone();

//Default subcat to “Orders”

ddSubcategoryUpdate(2);

});

Then we need an event to fire when the Category is changed.

$(function() {

$(“#_DropDownCategory”)

.bind(“change”, function(event) {

var eCat = this[this.selectedIndex].attributes(“Category”).value;

ddSubcategoryUpdate(eCat);

});

});

Note how jQuery allows us to wire up DOM events after the fact to our .NET controls.  Here we add an onchange event dynamically rather than injecting this via the codebehind which forces us to put javascript code in the wrong place.  All we’re doing is pulling the value of the enum from the selected Category and then passing it to a function which will update the Subcategory items.

function ddSubcategoryUpdate(eCat) {

//Remove all items from drop down

$(“#_DropDownSubcategory”).children().remove();

//For each subcat item: test if it belongs in eCat, if so add it

$(optSubCat).each(function() {

if (($(this).attr(“Category”) & eCat) > 0) {

$(“#_DropDownSubcategory”).append($(this).clone()[0]);

}

});

}

And finally, in the if statement we see we test each Subcategory item previously saved in memory to see if it matches the enum value of the Category.

What we’ve ended up with is a very powerful yet simple mechanism for cascading dropdowns using enums in our codebehind.  It’s easier to wire up than what the Ajax Control Toolkit provides, its all script so the UI looks good, and while this could have been done in straight javascript it demonstrates the power and simplicity of the jQuery library.

Visual Studio 2008 JumpStart December 18, 2007

Posted by codinglifestyle in ASP.NET, C#, Javascript, jQuery, linq.
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Yesterday I attended the Visual Studio 2008 Jumpstart at Microsoft in Dublin.  This was a one-day course, presented by David Ryan, introducing some of the new features in C# 3.0 and VS2008.

 

I approach every release with excitement and trepidation.  There are some fantastic new features like JavaScript debugging, nested MasterPages, improved IDE for both coding and web design, and multi-target runtime support.  With multi-targeting support we can use VS2008 to continue to code or support .NET 2.  If you open a VS2005 project, you will be prompted to upgrade your project even if you continue to use .NET 2.  I asked was there any risk associated with this for those who need to continue to support .NET 2 and was told only the SLN file is changed.  So theoretically, there is no reason to keep VS2005 installed!  Do you believe it??  If only we could get rid of VS2003 as well.

 

Now, the reason I also approach each release with trepidation is because you know there is going to be some big, new, ghastly feature which will be force-feed to us like geese in a pâté factory.  This time that feature in LINQ.  Open wide because there is a big push behind LINQ and you’ll notice a using System.Linq statement in every new class (which is a real pain if you change target framework back to .NET 2).  But first, let’s review some of the changes made to C#:

 

  • Anonymous types
    • var dt = DateTime.Today;
    • Anything can be assigned to a var, but once it’s assigned its strongly typed and that type can’t be changed.  So I can’t reuse local variable dt and assign string “Hello” like I could with object.
  • Automatic Properties
    • This:

      private int m_nID;

         public int ID

         {

             get

             {

                 return m_nID;

             }

             set

             {

                 m_nID = value;

             }

         }

 

  •  
    • becomes this:

public int ID { get; set; }

 

  •  
    • The problem is in practice I prefer to use the private variables in code leaving properties for external access only.  Many times the get/set is doing something interesting, like reading the value from a cache or performing some complex operation.  We don’t necessarily want/need this code to execute every time it is accessed from within the class so I use the private variable.  Automatic Properties has us using the public property directly everywhere in the class.  So, personally, this will cause inconsistency in my coding style.
    • You can also specify the get as public but keep the set to just be accessible from within the class like this:

public int ID { get; private set; }

 

  • Object initalizers
    • Ever have to instantiate your own class and have to initialize it with a dozen properties?  Do you add 13 lines of code or go overload the constructor?  Now you don’t have to, imagine a simple Person class with 3 properties:

Person person = new Person { FirstName=“Chris”, LastName=“Green”, Age=33 };

 

  •  
    • Only initialize what you properties you want:

Person person2 = new Person { FirstName = “Chris”, LastName = “Green” };

 

  • Collection initalizers

List<Person> people = new List<Person>

         {

new Person { FirstName = “Chris”, LastName = “Green”, Age = 33 },

new Person { FirstName = “Bill”, LastName = “Bob”, Age = 46 },

new Person { FirstName = “Foo”, LastName = “Bar”, Age = 26 }

         };

 

  • Extension methods
    • This is a way of adding new inherent functionality to existing classes.  The objective is to add a new method to the DateTime type called LastDay() which will return the last day of the given date’s month.

public static class DateTimeUtils

{

        public static int LastDay (this DateTime dt)

        {

            return DateTime.DaysInMonth(dt.Year, dt.Month);

        }

}

 

  •  
    • Notice the this before the first parameter argument.  This tells the compiler that this is an extension method for the DateTime type.  We can now use this method as if it was built in to the DateTime class:
      • int nLastDay = dt.LastDay();
  • Lambda expressions
    • Too lazy or couldn’t be arsed to write a small 2 line function?  This is for you:

Func<string, bool> CheckName = sName => sName == “Bob”;

bool bBob = CheckName(person.FirstName);

Func<int, int> Square = x => x * x;

int nSquare = Square(5);

 

The fact is there’s an ulterior reason var, Lamda expressions, and many of above additions have been added to C# 3.0.  C# had been bent in order to accommodate LINQ.  LINQ allows you to perform queries on objects, DataSets, XML, and databases.  It’s interesting in that it offers an independent layer of abstraction for performing these types of operations.  This has actually occurred to me before when looking at data layers chock full of embedded SQL not being particularly ideal.  LINQ offers a generic and powerful alternative.  Let’s take a look at a simple example based on the people collection from above:

 

var matches = from person in people

              where person.FirstName == “Bob”

              select person;

 

The first thing that caught my attention was the select was last.  One reason they likely did this was to force us to state what we were querying first (the from clause) so that Intellisense could kick-in for the rest of the expression.  Notice person.FirstName was fully supported by Intellisense so the Person class was automatically inferred from the people collection.

 

You can create objects on-the-go from your expression.  For example:

 

var matches = from employee in people

              where employee.FirstName == “Bob”

              select new Person(employee.FirstName, employee.LastName);

 

 

Notice how var is inherently handy here (but bad practice for nearly everything else) as our LINQ expression returns System.Collections.Generic.IEnumerable.  Lambda expressions as well play a key part in LINQ:

 

var matchesBob = people.Select(CheckName => CheckName.LastName == “Bob”);

 

matchesBob.ToArray()

{bool[3]}

    [0]: false

    [1]: true

    [2]: false

 

var matchesInitials = people.Select(ChopName => ChopName.FirstName.Remove(1) + ChopName.LastName.Remove(1));

 

matchesInitials.ToArray()

{string[3]}

    [0]: “CG”

    [1]: “BB”

    [2]: “FB”

 

There is so much more to LINQ that I won’t attempt to cover any more.  Rest assured you will hear much more about LINQ in the months to come (fatten up those livers).  One thing is obvious, C# took a heavy hit in order to support it.  Let’s hope it’s worth it as every release we lean more and more towards VB.  A colleague recently remarked, “C# is all VB under the covers anyhow”.  He might be right.

 

Some other interesting new additions:

  • XElement – for anyone who has programmatically built XML before you will appreciate this quicker alternative
  • ASP.NET ListView – the singular new control this release.  Its basically a Repeater but with design-time support
  • Script Manager Proxy – typically the Ajax ScriptManager will be placed in the MasterPage.  When the content page needs to access the ScriptManager a ScriptManagerProxy can be used to get around the restriction of only one ScriptManager allowed per page.
  • Javascript enhancements – built-in libraries which extend string, add StringBuilder, and a number of other enhancements to make writing JavaScript more .NET-like
  • CLR Add-In Framework: essentially a pattern for loading modules (only from a specified directory) vs. using reflection, iterating classes for a specified type, and using the activator to instantiate the object
  • Transparent Intellisense: In VS2005 Intellisense went in to hyperdrive and our tab keys have never been the same.  However, I often found myself cursing it as it often got in the way.  So when VS is being too helpful and you can’t see what you’re doing press CTRL rather than ESC to turn Intellisense transparent.
  • Right-click the code and you will see an Organize Using menu below Refactor.  Here is a feature I’ve often dreamed of: Remove Unused Usings.  Pinch me!  Also, if you right-click the interface in a class’s definition (public class MyClass : Interface) there is an Implement interface option.   Last, if you are coding away and using a class before adding a using statement use ALT-Shift-F10 to automatically resolve the class and add the using statement to your file.
  • Improved support for debugging multithreaded applications
  • SQL Database Publishing Wizard is now integrated in the VS
  • Did I mention JavaScript debugging??!

 

You may notice I’ve omitted a few big topics.  I didn’t mention Ajax because that’s old news now.  However, there are new versions of the Ajax Control Toolkit and web deployment projects for VS2008.

 

I also didn’t mention Silverlight although I may find some interesting applications for it in the future.  For example, if you really hate writing JavaScript you could use Silverlight’s built-in mini CLR to write C# code which executes in the browser.  Oh, I hear it does some UI stuff too.

 

References: ScottGu 19-11-2007, ScottGu 13-03-2007, ScottGu 08-03-2007, C# 3.0 In a Nutshell, Pro ASP.NET 3.5 in C# 2008, and CodeProject.

 

Numeric input only for a HtmlInputField January 12, 2006

Posted by codinglifestyle in ASP.NET, Javascript.
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1 comment so far

Sometimes a validator control is overkill, especially when you are dynamically creating all your web controls and just want a simple restriction.  Below is a little javascript to require numeric input only:

HtmlInputField myField = new HtmlInputField();

myField.Attributes.Add(“onkeyup”, “this.value=this.value.replace(/[^\\d]*/gi,\”\”);”);

Exposing C# controls as Active-X and the effects on developing with the download cache January 5, 2006

Posted by codinglifestyle in C#, Javascript, Winform.
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A C# assembly can be easily exposed as an Active-X control using the object tag like so:

<OBJECT id=”Bob” classid=”url to assembly#full name of control></OBJECT>

So for example my assembly is located in a virtual directory on server VM2003S2:88 called MyObject.  MyObject has a namespace of Chris.ActiveX.Controls and the class is MyControl.  My object tag would be: http://vm2003s2:88/myobject.dll#chris.activex.controls.mycontrol

This complete I can now use javascript to talk to “Bob” via MyControl’s public methods.  This is all well and good however you may experience frustration in seeing your updates during development.

The assembly is automatically pulled down to the download cache which is located in c:\windows\assembly\downloads on Win2003.  Unfortunately, its not smart enough to read version strings and realize a newer copy is available on the server.  Therefore you must clear this cache using:

gacutil /cdl

But that’s not all!  A copy is also made in your temporary internet files.  You won’t be able to simply delete it using del from the post-build event as Window’s treats the directory as special.  So either write a small program utilizing the API to delete your assembly from the cache or use one of the miriad of privacy utilities to clean this for you.  I found CleanUp! which can be quietly executed from the command line and added to my post build event.  The result is the assembly is pulled every time (on the development machine) so you see your changes with each build.

Here is a good example explaining Embedded Windows User Controls into Internet Explorer:

http://www.devhood.com/tutorials/tutorial_details.aspx?tutorial_id=187