AJAX.NET Cascading Dropdownlist

Ok, so I finally began my journey towards web 2.0 programming yesterday with the Cascading Dropdownlist and thought I would share on how it works and hopefully help anyone having trouble using it! The example I am going to show will use a SQL database to get the values for the dropdown lists but the code should get you in the right direction regardless of the Data Access you choose.

First thing you need to do is disable EnableEventValidation in the page directive.

 

<%@ Page Language="C#" AutoEventWireup="true" 
CodeFile="cascade.aspx.cs" Inherits="cascade" 
EnableEventValidation="false" %>

After that we need to add a couple of ASP DropDownLists:

<div>
    <asp:DropDownList ID="DropDownList1" runat="server">
    </asp:DropDownList><br />
    <br />
    <asp:DropDownList ID="DropDownList2" runat="server">
    </asp:DropDownList>

</div>

Now we need to add a ScriptManager and the CascadingDropDownList Control and point them to the dropdownlists, there are a few other properties of the Dropdown we need to set as well, but since we don’t have a web service yet we will wait to add those properties until later. What’s important here is that we are specifying which dropdownlist to control here with the TargetControlID property:

 

<div>
        <asp:ScriptManager ID="ScriptManager1" runat="server">
        </asp:ScriptManager>
        <asp:DropDownList ID="DropDownList1" runat="server">
        </asp:DropDownList><br />
        <ajaxToolkit:CascadingDropDown 
        ID="CascadingDropDown1" 
        runat="server" 
        TargetControlID="DropDownList1">
        </ajaxToolkit:CascadingDropDown>
        <br />
        <asp:DropDownList ID="DropDownList2" runat="server">
        </asp:DropDownList><br />
        <ajaxToolkit:CascadingDropDown
        ID="CascadingDropDown2" 
        runat="server" 
        TargetControlID="DropDownList2">
        </ajaxToolkit:CascadingDropDown>

</div>

The next thing we need to do is create a Web Service that will provide data for our dropdownlists. For my service I created DataService.asmx with the codebehind file DataService.CS. 

DataService.asmx only points to the CS file:

 

<%@ WebService Language="C#" CodeBehind="~/App_Code/DataService.cs" 
Class="DataService" %>

 

The rest of the code goes into the CS file. The first thing to note is that the CascadingDropDown requires the method are as follows:

 

[WebMethod]
    public CascadingDropDownNameValue[] 
GetDropDownData(string knownCategoryValues, string category)

With the exception that you can call your method "GetDropDownData" anything you would like but the type and params must stay that way for the call to be made which makes getting your paramaters out of the call just a little tricky. Let’s say our first DropDownList’s category is department and the value for it is DeptID which equals 2.. Well calling the knownCategory string will return Department:2; now if there were two dropdownlists one with category Department and one with category Employee knowcategoryvalues would return Department:1;Employee:John; etc. Luckily they made it easy to access these values using a stringdictionary like you can see here:

 

StringDictionary kv = 
CascadingDropDown.ParseKnownCategoryValuesString(
         knownCategoryValues);
        int DeptID;
        if (!kv.ContainsKey("Department") ||
            !Int32.TryParse(kv["Department"], out DeptID))
        {
            return null;
        }

This example finds the entry with the key Department and then pulls out an int from it’s value, so if our Catgory is Department and our value is 3 it would pull out a 3 which we can now use in our code to get the next list of items. If you wanted to just pull the value as a string you could change the code to look as so:

 

StringDictionary kv = CascadingDropDown.ParseKnownCategoryValuesString(
         knownCategoryValues);
        string DeptID = kv["Department"].ToString();

 

Either way it will pull the value. Ok, now that we have that out of the way let’s look at the full code for our Web Service:

 

using System;
using System.Web;
using System.Collections;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Web.Services;
using System.Web.Services.Protocols;
using AjaxControlToolkit;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;

/// <summary>
/// Summary description for CarData
/// </summary>
[WebService(Namespace = "http://tempuri.org/&quot;)]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
[System.Web.Script.Services.ScriptService()]

public class DataService : System.Web.Services.WebService
{
    public DataService()
    {
        //Uncomment the following line if using designed components 
        //InitializeComponent(); 
    }

    [WebMethod]
    public CascadingDropDownNameValue[] 
GetDepartments(string knownCategoryValues, string category)
    {
        using (SqlConnection connection = 
new SqlConnection(ConfigurationManager.ConnectionStrings["MyConnectionString"].ConnectionString))
        {
            using (SqlCommand command = new SqlCommand("GetDepartments", connection))
            {
                command.CommandType = CommandType.StoredProcedure;
                connection.Open();
                List<CascadingDropDownNameValue> values = new List<CascadingDropDownNameValue>();
                using (SqlDataReader reader = command.ExecuteReader())
                {
                    while (reader.Read())
                    {
                        int id = (int)reader["DeptID"];
                        string Department = (string)reader["Department"];
                        values.Add(new CascadingDropDownNameValue(Department, Convert.ToString(id)));
                    }
                }
                return values.ToArray();
            }
        }
    }

    [WebMethod]
    public CascadingDropDownNameValue[] GetEmployees(string knownCategoryValues, string category)
    {

        StringDictionary kv = CascadingDropDown.ParseKnownCategoryValuesString(
        knownCategoryValues);
        int DeptID;
        if (!kv.ContainsKey("Department") ||
            !Int32.TryParse(kv["Department"], out DeptID))
        {
            return null;
        }

        using (SqlConnection connection = 
new SqlConnection(ConfigurationManager.ConnectionStrings["MyConnectionString"].ConnectionString))
        {
            using (SqlCommand command = new SqlCommand("GetEmployees", connection))
            {
                command.CommandType = CommandType.StoredProcedure;
                command.Parameters.Add(new SqlParameter("@DeptID", Convert.ToString(DeptID)));
                connection.Open();
                List<CascadingDropDownNameValue> values = new List<CascadingDropDownNameValue>();
                using (SqlDataReader reader = command.ExecuteReader())
                {
                    while (reader.Read())
                    {
                        int id = (int)reader["DeptID"];
                        string firstname = (string)reader["FirstName"];
                        values.Add(new CascadingDropDownNameValue(firstname, Convert.ToString(id)));
                    }
                }
                return values.ToArray();
            }
        }
    }
}

At the top of the web service you will notice the namespace [System.Web.Script.Services.ScriptService()], without this you will only get errors, so make sure you place this in your web service! The Array returned also needs to be from CascadingDropDownNameValue so make sure when you create your array you use List<CascadingDropDownNameValue> values = new List<CascadingDropDownNameValue>(); and then populate the values!

Ok, now we can go back to your code and add our service path, service method, category and prompt text. Also in the second Dropdownlist we need to add a ParentControlID so it knows it will be updated by DropDownList1

 

     <div>
        <asp:ScriptManager ID="ScriptManager1" runat="server">
        </asp:ScriptManager>
        <asp:DropDownList ID="DropDownList1" runat="server">
        </asp:DropDownList><br />
        <ajaxToolkit:CascadingDropDown 
        ID="CascadingDropDown1" 
        runat="server" 
        TargetControlID="DropDownList1" 
        ServicePath="DataService.asmx" 
        ServiceMethod="GetDepartments" 
        Category="Department" 
        PromptText="pick Department">
        </ajaxToolkit:CascadingDropDown>
        <br />
        <asp:DropDownList ID="DropDownList2" runat="server">
        </asp:DropDownList><br />
        <ajaxToolkit:CascadingDropDown
        ID="CascadingDropDown2" 
        runat="server" 
        TargetControlID="DropDownList2" 
        ServicePath="DataService.asmx" 
        ServiceMethod="GetEmployees" 
        ParentControlID="DropDownList1" 
        Category="Employee" 
        PromptText="pick employee">
        </ajaxToolkit:CascadingDropDown>
    </div>

And that is it! I hope this helps someone getting started with Ajax.NET

C# Toggle

Since I have had this question asked a few times now I thought I would do a little write up on it for search engines.

I have found the best method to toggle something back and forth is to use a boolean value with a not clause. The class would look as follows:

public class Toggle{
    private static bool x;

    public static bool X
    {
        get
        {
            return x;
        }
        set
        {
            x = value;
        }
    }
}

Now all we need to do is toggle the value of X and because we used a bool this is very simple because there are only two possible values!

Toggle.X = !Toggle.X;

This says if X is true it will be false and vice-versa! To show how it would be used in a real world example I will use a scenario I was given today where someone wanted to only show the top three rows of a gridview but have a show/hide button that will allow it to be shown or not to preserve screen space. I am not going to post the code for the gridview because it could be anything and work with this example but here is the code for the toggle and show/hide:

protected void btnToggle(object sender, EventArgs e)
    {
        Toggle.X = !Toggle.X;
        GridView.DataBind();
       
    }

    protected void GridView_RowDataBound(object sender, GridViewRowEventArgs e)
    {
        int ind = e.Row.RowIndex;
        if (Toggle.X == false)
        {
            btnToggle.Text = "Show";
            if (ind >= 3)
            {
                e.Row.Visible = false;
            }
        }
        else
            btnToggle.Text = "Hide";
    }

And that it is it! Not a whole lot to it thanks to the Bool = Not Bool method! Please note that this is not the best method to show rows if it is a large number because it returns all the records regardless if you want to show them or not. Thanks to Sql 2005 there is an easy way to accomplish this but that is for another time. 

A very nice weekend!

Had a great day yesterday with my cousins! From the last visit they found out I had never seen the movie Matilda so as soon as I arrived my little cousin insisted we watch it=D So glad we did too, what a great story! My favorite part is when she learns that people that misbehave have to be punished and she decides her father needs to be punished! So funny=D Now I am going to have to get the book!

The rest of the day consisted of a wonderful walk and card games. It is funny, cause just a year ago I used to let her win when playing cards to keep it fun, but now I can’t seem to win for the life of me! Pretty soon, she might have to let me win:) The walk was also a lot of fun and I included some pictures from the walk below! I hope everyone else had a great weekend as well!

I was worried this picture was going to be too grainy, but it is now one of my favorites!

I am not sure what she was thinking about in this photo, but we had just past two huge bird nests and she was pretty sure they were from an eagle or halk, so that is my best guess

During the walk we came across this place where she remembered being stuck in the mud when she was younger and is telling me the story

Has been a long time…

My little break took a little longer than I initially anticipated! Life gets so busy sometimes and especially right now I just have this urge to learn so many things. Photography has really been a large part of this learning craze and I have to admit that I am having the time of my life! Lighting especially has my attention, amazing what fun it is to play with light! I am still just learning and it is a hobby but here are two picture of my favorite models from this past week and of course there are many more on flickr if you want to look around!

This picture is supposed to be her looking out at kids playing while she is stuck in the house. It was so funny, cause I told her to pretend this and she said, "so there are kids out there playing and I am stuck here with you".. of course she laughed when she said=D as did I. She is such the character! 

 

This picture is of grandma where she was helping me test lighting. I need to redo it because well I messed up the lighitng, but I still like her in it!

 

 

 

Besides photography I am still really into programming, but am just not very good at it:) I still love it but I have sooo much to learn. I did write my first gadget which is on the top left of my blog that shows someone’s interesting photos from flickr! I will be the first to admit it needs a lot of work but I guess we all have to start somewhere=D How it works is I wrote a program that pulls your six most interesting photos based on your flickr id, which isn’t exactly what you might think it is. Actually in the program I wrote it accepts your email, userid or flickr id, but for the gadget thought it would be better to avoid confusion and just get right to the source. To find this id you have to go to http://www.idgettr.com and enter the url to your flickr stream. This will produce your flickr id and you can then just paste it into the gadget. Of course this option is only available when you are in edit mode too. After you set the id you can exit edit mode and viola your pictures appear, or at least they should lol. Have already had some reported issues of them not showing up, so use at your own risk:)

Well I hope everyone had a great holiday season and I hope to be around a little more this year!

Gone Fishing

Just kidding! Geez this place looks nice:) Thanks to all who took care of it while I was gone. Actually I am not really back, summer is over and life is busy, just wanted to let people know I probably will not be spending time here until I finish some things I am working on. I can’t completely give up on my photography obsession, so if you want you can check out my flickr site, but even the photos there are old right now I am afraid:) I am not sure how long this break will be but I will come visit your sites when that time comes so no need to come to this ghost town in the meantime! Take care!!

I really love walks..

I prefer my walks in the mornings and evenings when you have that dreamy atmosphere, but anytime I am walking I am usually pretty happy. Something about just walking feels like an adventure. It is probably because I am normally either in a car, working or on the computer that I find walking with no purpose so liberating.

Luckily for me, my little cousin also loves to walk! In fact, I think she likes it even more than I do! When she is walking with you the adventures turn into fairytales and the places you visit each have their own magical aspect. She will come up with the greatest stories of why a branch is on the ground or find a message in a piece of paper she finds! This evening it was a “wanted poster” and the neverending movie that spurred her imagination! So much fun having her around and I really wish she lived closer! Anyhow, I took some photos on our walk tonight and attached a few, but the rest can be found here!

 

Jazz Concert!

A friend/colleague of mine teaches music and this summer he put together a jazz band for kids that wanted to participate and I must say the results of his training were really phenomenal! I am not a big fan of jazz on vinyl but “live” it is always so fun to just see the musicians go off in their own little worlds. Some of these kids couldn’t have been any older than 11 years old, but they were all not only amazing, but so into the music you couldn’t help but smile watching them!

The solos in particular were such a joy to watch, especially the pianist and saxophone player who really put on a show. It was funny cause before the show started the teacher explained that the audience is supposed to clap after each solo while watching jazz and it didn’t matter if it was good or not=D Luckily they were all worth applause though!

Watching this reminded me of just how rewarding teaching can be and I started to regret that I was not going to teach this year. However, I think I can also do with a break from disciplinary issues too=D

I love music!

Music was always big in my family! My dad not only owned a music store for a short time but can also play anything with strings. He is such a talented musician and especially when I was little he used to perform with his friends at our house and I used to look forward to them visiting so much. Forget concerts, we had the best band in the world as the house band. He also led the music for the church and although I can’t recall a single sermon you can bet I know pretty much every song he ever sang. For Christmas when I was around 15 I got my very own guitar, a Jackson Dinky XL which is to this day the greatest gift I have ever received. All through high school that guitar was my companion. It didn’t matter where I was going, that guitar was coming along and if it wasn’t you knew I would find one wherever I was going. I was never very good, but it didn’t really matter. As long as I was playing I was happy in my own little world.

Even today if things get bad or I am sad I can always count on my guitar to take me away from it all, although these days I prefer it acoustic:). Music should be a part of everyone’s lives in my opinion! The greatest escape

 

Five Things…..

I almost forgot with all the changes today, but I was tagged earlier by Grace to list five things. Not sure if I could choose the categories or not, but anyhow I just used the categories she had listed! 

 

5 Things in my Freezer…
     Hmmmm… I could make up some things I would like in there, but I don’t have a single thing in my freezer. No lie

 

5 Things in my Closet…

     Kitties Food and Water
     Kitty toys
     Old empty fish tank I have put off putting back together for fishies
     3 pairs of pants
     A bunch of shirts I hardly wear because I only like a few of them

 

5 Things in my Vehicle…
     Usually my Canon Camera
     My CD changer which currently has some cd’s my brother made for me on my last road trip
     Aspirin, just in case I have to take a road trip with someone that talks too much
     AAA Card just in case my car breaks down
     Insurance and registration just in case I break the law

     oh, I also forgot, but I usually have tons of change in my car. I usually let kids clean my car out and keep whatever change they find which is sometimes like 50 dollars=0. Usually they are so stoked:)

 

5 Things in my Purse
     Just because I know who Heidi is Grace, does not mean I own a purse! I will keep my diginity on this one and pass:)

5 Things on my Desk
     Model Painting kit, been using this quite a bit lately but no good models yet
     Picture of my friend Megan
     My Speakers
     Keyboard and mouse
     Two tickets to the play Wicked I am trying to sell

I am becoming a regular chef!

First Grace’s wonderful Salmon and last night I made my grandma Sea Bass with Sautéed vegetables. It was a huge hit too!

Usually grandma eats just a little of everything and is very critical of food, but she called it delicious! Coming from her with food that is big=D I can’t actually take too much credit for this wonderful dinner though, cause my friend Sophie made the marinade which really made the whole dinner. So delicious! I tried to get the recipe from her, but she said it is her secret recipe:). Don’t worry, I will get it one of these days and post it!

I also hung out with my old friend Travis the bird! He is the coolest cockatiel ever! Well, actually I think he is a little slow, cause I read somewhere they can learn to talk and I used to spend hours upon hours trying to teach him things to say to my then girlfriend, but he never learned a single word:( He does whistle at me though! I wish I had taken pictures of dinner, but I did get a picture of grandma and Travis