Using orderby with an EntityDataSource

This can be confusing when you are selecting all (*)

In a LinqDataSource if you want to sort by a column called 'item_id' you simply put:
sortyby="item_id"

but if you use that syntax with a EntityDataSource you will get this error:
System.Data.EntitySqlException: 'group_name' could not be resolved in the current scope or context. Make sure that all referenced variables are in scope, that required schemas are loaded, and that namespaces are referenced correctly., near simple identifier

But in an EntityDataSource you will need to do:
sortyby="it.[item_id]"

Notice that it will always be it. That confused me for a while... the problem is that if you are selecting certain items and not using the auto-update, insert or delete features, the orderby dialogue in the GIU is very simple, but when you want to use these features, it mysteriously disappears.

Improved SaveAs() Method on the FileUpload Control

This extension handles things such as duplicate filenames and on-the-fly directory creation

Previously I showed how to save multiple files of the same name which I have used many times, so much in fact that I figured I would make a universal drop-in extension for it.

This new extension improves on the SaveAs() method in a few ways:
  • If a directory doesn't yet exist, it will be made
  • If a file already exists with the same file name, an incremented tag will be added: abc.pdf, abc[1].pdf, abc[2].pdf, etc.
  • It returns the name the file was saved with

There are two ways to call it:
  • FileUploadControl.SaveAsNoOverwrite() :: will save to the current directory with the 'FileName' property of the 'FileUpload'
  • FileUploadControl.SaveAsNoOverwrite(path) :: where 'path' is the path to save to

Here is the code:
public static string SaveAsNoOverwrite(this FileUpload up, string saveas)
{
  string[] split = saveas.Split(new char[] { '\\', '/' }, StringSplitOptions.RemoveEmptyEntries);

  string directory = string.Empty;
  for (int i = 0; i < split.Length - 1; i++) directory += split[i] + "\\";

  string filename = split[split.Length - 1];

  //saves to current directory if only filename is specified
  if (string.IsNullOrEmpty(directory)) directory = HttpContext.Current.Server.MapPath(".") + "\\";
  //creates directory if it does not exist
  else if (!Directory.Exists(directory)) Directory.CreateDirectory(directory);

  string[] fileNameSplit = filename.Split(new char[] { '.' });
  string ext = "." + fileNameSplit[fileNameSplit.Count() - 1];
  string prefix = filename.Substring(0, filename.Length - ext.Length);

  int count = 1;
  // if the files already exists, this will append a [x] where x is 0+(number of files existing with the same name)
  while (File.Exists(directory + filename))
  {
    filename = prefix + "[" + count.ToString() + "]" + ext;
    count++;
  }
  up.SaveAs(directory + filename);
  return filename;
}

public static string SaveAsNoOverwrite(this FileUpload up)
{
  return up.SaveAsNoOverwrite(up.FileName);
}

Getting started with Linq-To-Entities tutorial

The transition from Linq-to-SQL to .Net's Entities framework is incredibly simple

In my humble opinion, Linq is easily the greatest thing .Net has come out with in the past few years, and along with it, Linq-to-SQL (L2S) was a godsend. Being quick to hop on the L2S bandwagon, I quickly became a huge fan of the framework, it is amazing easy and useful. That being as it is, I was quite disappointed when I heard that Linq-to-SQL was no longer going to be advanced at all. Now, it is surely not dead, it is still very usable and effective at what it does, but I like to stay with frameworks that will be actively advanced and fbug-fixed. So I decided to make the jump to Linq-to-Entities (L2E), and it was suprisingly simple.

This guide should be a good starting point for anyone whether or not they are familiar with L2S, and a quick 'jumping guide' to L2S developers. Here's how to get started:

Make your ADO.NET Entity Data Model (.edmx file)

This is comparable to the .dbml file that you made with L2S.
  • Right click on your App_Code folder and select New Item
  • Select ADO.NET Entity Data Model and name it (I left the default Model.edmx for the example)
  • Choose Generate from database and click Next
  • Choose your database from the dropdown and choose the name to save the ConnectionString as and click Next
  • Choose all the things you want included, I just chose tables, but you may want to include views and SPs if you have them
  • *Be sure to remember the Model Namespace you choose for your .edmx (I will use DatabaseModel for the example) - click Finish

Now it will take a moment to run through and produce your .edmx; when it is done you will see a nice little representation of your tables reminiscent of the .dbml display in L2S:

Access your .edmx

Now we simply access the .edmx much like we did with L2S. You must remember to add Using DatabaseModel (or whatever your namespace was) to the code where you are using it. Now we will make a DatabaseModel object and use it to add a 'product' to the database. First, you need to make your Entity Access Object:
DatabaseEntities db = new DatabaseEntities();

Then you can use it to enter an object:
products p = new products();
p.product_name = "Word Processing Software";
p.price = 99;
p.stock = 100;
db.AddToproducts(p);
db.SaveChanges();

Once again, if you are familiar with L2S, this is almost the same exact thing! If you are new, this is very straight-forward and should be easy to understand:
  • Make an object of a type inside your database
  • Fill the object up with data
  • Put it into the database
  • Save the changes

Now L2E one-ups L2S and makes data entry even easier, this will accomplish the same as above:
db.AddToproducts(products.Createproducts(0, "Accounting Software", 300, 125));
db.SaveChanges();

Notice that the 'product_id' is entered as '0', that is because it is auto-incrementing, so it doesn't matter what I put there, it will be ignored. Now I don't know about you, but that little bit there will save me hundreds of lines of code! I am starting to like L2E already!

Display your data

Now that we have put a few objects in to the database, we can go and check it out. Later we will dig in with code, but first we will use a LinqDatasource/GridView:
  • Drag a LinqDataSource (LDS) on to the page and click Configure Data Source from the little square on the upper right of the LDS
  • Choose your Object Model and click Next
  • Choose your table and click Finished
  • Drag a GridView (GV) on to your page
  • In the GV option box, choose your datasource from the dropdown

now just view your page:

Modify Data

Now that we have seen how to put in data, we will modify some; once again, L2E makes it trivially simple:
products edit = (from p in db.products where p.product_id == 2 select p).First();
edit.product_name = "Account Software v2";
db.SaveChanges();

The Linq statement is EXACTLY like it would be in L2S, and just like in L2S, you can shorten up this with some Lambda integration; this will accomplish the same thing:
db.products.First(p => p.product_id == 2).product_name = "Accounting Software v2.1";
db.SaveChanges();

Deleting Items
Now that we have seen Insert and Update, the next logical step is Delete, and it is just as easy. Let us delete the 'Word Processing Software' frorm the table:
products del = (from p in db.products where p.product_id == 1 select p).First();
db.DeleteObject(del);
db.SaveChanges();

And the same exact thing shorthand with Lambdas:
db.DeleteObject(db.products.First(p => p.product_id == 1));
db.SaveChanges();

Once again, I have to say I like the approach that L2E takes of that of L2S, as it is not necessary to specify which table to delete from, as an object can only be deleted frorm the table that it is in.

Using your database relations

As in L2S, L2E takes great advantage of well designed databases and relations. If you noticed up above, the two tables in my database have a 1 to many relation frorm product to reviews. Each element in the 'reviews' table is required to relate to an element in the 'products' table (column 'product_id'). Let's fill the DB with a few more products and some reviews; a lot is going to go on here:
products p1 = db.products.First(p => p.product_id == 2);
products p2 = products.Createproducts(0, "Strategy Game", 49, 99);
products p3 = products.Createproducts(0, "Sports Game", 39, 99);
db.AddToproducts(p2);
db.AddToproducts(p3);

reviews r1_1 = reviews.Createreviews(0, "Much Improved", "this is a much better version", "Bill Brasky");
r1_1.productsReference.Value = p1;
reviews r2_1 = reviews.Createreviews(0, "Terrible", "worthless", "Dirk Digler");
r2_1.productsReference.Value = p2;
reviews r3_1 = reviews.Createreviews(0, "Great Game", "very tough AI", "Wonderboy");
r3_1.productsReference.Value = p3;
reviews r3_2 = reviews.Createreviews(0, "Very Fun", "the Bears rule", "Mike Ditka");
r3_2.productsReference.Value = p3;

db.AddToreviews(r1_1);
db.AddToreviews(r2_1);
db.AddToreviews(r3_1);
db.AddToreviews(r3_2);

db.SaveChanges();

Now to explain what just happened:
  • The first line gets an object of type products where product_id == 2 (this is 'Accounting Software v2.1')
  • The next two lines create new products
  • The next two submit those into the database

Now we have a total of 3 objects in the 'products' table and none in the 'review' table, that is where the next 8 lines come in. If you break up those 8 lines into pairs of two, you can see they are all the same thing really:
  • Make a new object of type reviews
  • Assign its foreign key reference to a products object

Since the database requires a relation between these two tables, you must be sure to set the reference. The last lines just submit everything and commit them to the database.

Now that that is in there, you can use the real power of relations in L2E. Once again, it is almost the same as L2S:
foreach (products p in (from _p in db.products select _p))
{
  Response.Write("<h3>" + p.product_name + " - $" + p.price + "</h3>");
  Response.Write("<b>Reviews:</b><div style='border:1px solid navy;padding:5px;'>");
  p.reviews.Load(); // this loads all the reviews that relate to the product p
  foreach (reviews r in p.reviews)
    Response.Write("<b>" + r.title + " - " + r.reviewer + "</b><br />" + r.review + "<br />");
  Response.Write("</div><br />");
}

And this is what you get:
Yes, I know I used the ugly 'Response.Write', and the output is hideous... but this is just a demo people! As you can see, it is incredibly easy to iterate through all of the reviews of a products, this big difference being that you need to call the .Load() method or they will not be populated. Now this is both a blessing and a curse; this is very efficient as it only loads the related objects if need be, but... it is soemthing that is easy to forget and may leave you scratching your head. I think I like it.

Now relations also work the other way as well. Say you have a reviews object, and you want to know the price of the products it is related to. No need to actually look up the products object, you just call the relation:
reviews r = db.reviews.First(_r => _r.review_id == 3);
r.productsReference.Load();
Response.Write("Price: $" + r.productsReference.Value.price.ToString());

Once again, notice that you have to Load() the reference, or you will get nothing.

Now that should get you started. Like I said, if you are familiar with L2S, this transition should be no problem, and if you are new to this whole Linq arena, this should be simple to pick up. This new ADO is getting more and more impressive the more MS works on it. I can't even imagine goging back to the old methods...

Simplify setting your DropDownLists to a specific value

An extension to quickly and easily set your DropDowns while avoiding errors

Sometimes you want to set your DropDownList to a value that may or may *not* be in the DropDownList, but setting that can be a bit tricky as it will often error out. This extension will avoid that and give you a simple way to set your DropDownLists wihtout all the extra code:
public static void Set(this DropDownList ddl, string findByVal)
{ // attempts to set a DDL to the 'findByVal'
  try { ddl.SelectedIndex = ddl.Items.IndexOf(ddl.Items.FindByValue(findByVal)); }
  catch { };
}

Now just call it from your DropDownList:
SomeDropDownList.Set("Some String Value");

And it will attempt to set your DropDownList to that value, but *not* error out if it doesn't exist.

Simple Dynamic Sorting Headers for GridView using indication arrows

A simple centralized way to make a nice flipping indicator (arrow) of which way you are sorting on a GridView

When sorting with gridviews, it is nice to have an indicator of which direction you are sorting on which field like the use at Yahoo! Autos. To copy this idea, I simply made 3 Css classes 'sort', which is a base class with no backgorund image, 'up' which has an up arrow, and 'down' which has a down arrow in it. I made sure to put the backgorund image in just once, and push the text away so it can show through. Also, since these will be applied to the Header element of the GridView, you have to make sure you declase '.class a':
.up a, .down a, .sort a { display:block; padding:0 4px 0 15px; }
.up a, .down a { color:#8F5F00; }
.sort a:hover { background:#ffcc66; }
.up a { background:url(../images/up.gif) left no-repeat; }
.up a:hover { background:url(../images/up.gif) left no-repeat #ffcc66; }
.down a { background:url(../images/down.gif) left no-repeat }
.down a:hover { background:url(../images/down.gif) left no-repeat #ffcc66; }

Now, I made a function in a helper Class that will take in the same arguments that a GridView Sorting event throws, that way the transition will be easy.
// This is used to flip the sorting arrow up/down
// Base Css class is 'sort', the Ascending Css Class is 'up' and Descending is 'down'
public static void GVSort(object sender, GridViewSortEventArgs e)
{ // call on sort and sets the sorted field to the proper Css Class, while setting all others to the base class
  string BASE = "sort";
  string UP = "up";
  string DOWN = "down";
  GridView g = (GridView)sender;
  for (int i = 0; i < g.Columns.Count; i++)
  {
    var c = g.Columns[i];
    c.HeaderStyle.CssClass = c.HeaderStyle.CssClass.Replace(UP, BASE).Replace(DOWN, BASE);
    if (c.SortExpression.Equals(e.SortExpression))
    {
      c.HeaderStyle.CssClass =
        e.SortDirection.Equals(System.Web.UI.WebControls.SortDirection.Ascending) ?
          c.HeaderStyle.CssClass.Replace(BASE, UP).Replace(DOWN, UP) :
          c.HeaderStyle.CssClass.Replace(BASE, DOWN).Replace(UP, DOWN);
    }
  }
}

Now say I had this in a class utils.cs I would just call it one the GridView Sorting event:
protected void gv_Sorting(object sender, GridViewSortEventArgs e)
{
  sao.GVSort(sender, e);
}

And there you have it! You can call that from every Gridview in your application that you want to look similar - code only once!

A simple way to add a 'View All' sort option to your DataSource in Asp.Net

Just use a little SQL trick to simplify and add usability to your DataSource

Often times I have integer fields in my database that serve as categories. These categories are very helpful when sorting for the users, butit is sometimes tough to write a simple, one-line query to output ALL of them; I figured an extremely simple way to do this. This may be a little hard to explain, but it is very useful.

For this example, I am going to use a LINQDataSource

<asp:LinqDataSource ID="ldsCases" runat="server" ContextTypeName="dbDataContext" TableName="Cases" Where="Category == @Category">

   <WhereParameters>

     <asp:SessionParameter Name="Category" SessionField="Cat" Type="Int32" />

   </WhereParameters>

</asp:LinqDataSource>


This is using a Session variable to work with the DataSource which will be set the the integer value that corresponds to the category I want to find. Now this will work just fine if we are trying to just look at a single category, but what if we want to look at all of them? It is really quite simple, now, just add one more OR (||) statement to our SQL and set the Session variable to 0 any time we want to call everything:

<asp:LinqDataSource ID="ldsCases" runat="server" ContextTypeName="dbDataContext" TableName="Cases" Where="(Category == @Category) || ((Category * @Category) == 0)">

   <WhereParameters>

     <asp:SessionParameter Name="Category" SessionField="Cat" Type="Int32" />

   </WhereParameters>

</asp:LinqDataSource>

GUI css writer: change your page style and rewrite your css on the fly

I have seen a lot of theme pickers out there, but not one that gives you 100% control like this

While working on a recent project, I had a complaint about the colors... I hate colors and I am no good at picking them, and when I do find some colors that I think are nice, apparently everyone else thinks they are crap.  This is why I truly respect web designers, as that is a true skill.  But to my chagrin I do not have a web designer, so I did the next best thing: get the blame off my back.  That's right, if you think you are so good with colors, why don't you pick them Mr. User?

 

So I went ahead and used the Farbtastic jQuery color picker Plug-in that I recently fell in love with, along with some nice Linq, XML, some good old .Net IO and a dash of clever css writing, and I was able to put together a (almost) fool-proof theme-designer with a friendly GUI.

 

First thing first, I needed both jQuery and the Farbtastic jQuery color picker Plug-in I just mentioned to be downloaded and called in my <head>.  Once I ran the Farbtastic demo to make sure everything was working fine, I set out on my adventure.

 

Next, I had to seperate my css into two distinct sheets, one: main_style.css would be jsut that, the main style; this never changes and is static.  Then, I made another stylesheet: theme.css that will hold my changing data and be re-written.  By using some clever techniques like not relying on any css border properties, I will be able to minimize the amount of code i have to re-write and be able to produce what looks like borders without actually using borders.  So instead of

/*theme.css*/
div.border { border: solid 5px Black; }

<!--html-->
<div class="border">some stuff with a border</div>

 

I will instead use something like this:

/*main_style.css*/
.border { padding:5px; }

/*theme.css*/
.border_color { background-color:Black; }
.content_color { background:White; }

<!--html-->
<div class="border border_color">
  <div class="inner_color">some stuff with a border</div>
</div>

 

These both produce what looks to be the exact same, the difference being that the second one does not actually have a border, it just looks like it with the padding and background color.  Now I know that the second one is more code, but that is the price you pay to have less code in your css and have your website be maintainable.  Once you write teh css writer one time, you will never have to touch the code again.  You can easily incorporate borders into the re-written css if you would like, that is just not the path I am going.

 

Now that that is understood, I can put in the color picker and the related TextBox controls to correspond to what colors I will be changing.  To do that, simply put this isnot your page where you want the picker: <div id="picker"></div> and then add your TextBox controls where you need them; each TextBox is the class 'colorwell' that allows them to be accessed easier by jQuery.  Once that is done, add a Button to submit everything.  So far, mine looks like the picture at the top of the post.  You will have to bind everything with jQuery now:

[code:js]

 <script type="text/javascript" charset="utf-8">
     $(document).ready(function() {
         var f = $.farbtastic('#picker');
         var p = $('#picker').css('opacity', 0.25);
         var selected;
         $('.colorwell')
      .each(function() { f.linkTo(this); $(this).css('opacity', 0.75); })
      .focus(function() {
          if (selected) {
              $(selected).css('opacity', 0.75).removeClass('colorwell-selected');
          }
          f.linkTo(this);
          p.css('opacity', 1);
          $(selected = this).css('opacity', 1).addClass('colorwell-selected');
      });
     });
 </script>

[/code]

 

Now comes the code-behind.  First thing I decided is that I am going to hold the data in an xml file; you could easily do this in a SQL database as well.  I named the file theme.xml and it looks like this:

<?xml version="1.0" encoding="utf-8"?>
<theme>
  <text>#444444</text>
  <borders>#4a4a4a</borders>
  <body>#ffffff</body>
  <links>#ff7700</links>
  <link_hover>#ffa500</link_hover>
  <button_text>#ffffff</button_text>
  <headers>#ffffff</headers>
  <background>#a53c3c</background>
</theme>

 

I populated it with my default color values of what will be changing.  Next, I made a class that will help me interact with the xml using Linq, I named this file xmlHelper.cs and placed it in my App_Code folder:

public static XElement getElement(XElement x, string element)
{ return (from e in x.Descendants(element) select e).First(); }

public static void writeElement(XElement x, string element, string value)
{
    XElement xe = getElement(x, element);
    xe.Value = value;
}

 

Now in my Page_Load I made a Dictionary<string, TextBox> and populated it with all of my TextBox controls and their corresponding xml Element name.  Now each time the page loads fresh, I simply load my values into the TextBox controls like this:

if (!IsPostBack)
{
    foreach (var v in colors)
        v.Value.Text = xmlHelper.getElement(x, v.Key).Value;
}

 

Now every time the page loads, it pulls the values out of the xml file and populates the TextBox controls.  Now that I have that, I need a way to write to the css file and the xml file.  A iadd that to my btnSubmit_Click event.  Once again, I can look through the Dictionary I had set up to this time use my xmlHelper class and write to the xml file.  That is done like this:

protected void btnSubmit_Click(object sender, EventArgs e)
{
    foreach (var v in colors) xmlHelper.writeElement(x, v.Key, v.Value.Text);
    x.Save(themePath);
    //writeCss(); //this will be used in a moment
}

 

Now the xml is written, we need to write the css.  For this I just use the old IO and StringBuilder to write my css and overwrite the old file:

protected void writeCss()
{
    string cssThemeFile = Server.MapPath("~") + "\\css\\theme.css";
    StringBuilder sb = new StringBuilder();
    sb.Append("html{background-color:" + txtBg.Text + ";}");
    sb.Append(".border_color{ background-color:" + txtBorders.Text + ";}");
    sb.Append(".content_color{ background-color:" + txtBody.Text + ";}");
    sb.Append(".header_text{color:" + txtHeader.Text + ";}");
    sb.Append("a{color:" + txtLink.Text + ";}");
    sb.Append("a:hover{color:" + txtLinkHover.Text + ";}");
    sb.Append(".button:hover{background-color:" + txtLinkHover.Text + ";}");
    sb.Append(".button{background:" + txtLink.Text + ";color:" + txtButtonText.Text + ";}");
    File.Delete(cssThemeFile);
    TextWriter tw = new StreamWriter(cssThemeFile);
    tw.WriteLine(sb.ToString());
    tw.Close();
}

 

That will write my theme.css file, and that is that.  Now on every click, the values will be written to the xml file (this is unneccessary, but it loads the previous settings up for your user).  After that, the css file is re-written and immediately used by your page.  This does require that you have write permissions to whatever directory/directories you house your theme.css and theme.xml files in.  This also is easy to implement with each user profile having their own saved style (easier with SQL).  I hope this comes in handy for someone, I love it and have used it on a few projects now.

 

...And now they see it's not soo easy picking colors that actually look good :)

 

 

Saving multiple files of the same name (C#)

Save multiple files of the same name without overwriting anything

I am sure I am not the only one to run into the problem of saving files with the FileUpload control.  The problem with this can be if a user has already uploaded a file someFile.txt and they are trying to upload another file someFile.txt.  Normally, you have 2 options:

  • Delete the old file and save the new one
  • Inform the user there is already a file there under that name


Recently, one of these options just wouldn't cut it, so I borrowed an idea from Microsoft Windows: if you save two identical files on your desktop, it simply changes the filename slightly.   For example, if there is already someFile.txt on my desktop, and I try to paste a file with the same name, Windows will just rename it Copy of someFile.txt and if I paste again, it will be named Copy (2) of someFile.txt.  Now that is a decent idea, but I hate the 'Copy of' part of the name, so I decided to make that part a little better.

 

What this snippet does, is take in the FileUpload control you are saving from and saves it to the directory you specify (saveTo).  It will first try to save the file as someFile.txt, but if that is already there, it will save as someFile[1].txt and if that is there it will save as someFile[2].txt and so on.  This is very handy if you need to keep mulitple versions of one file.  It return a FileInfo object so you can get the name it saved as, file size, etc..

 

[code:c#]

public static FileInfo saveFileWithoutOverwrite(FileUpload fu, string saveTo)
{
    int count = 1;
    string fileName = fu.FileName;
    string[] fileNameSplit = fileName.Split(new char[] { '.' });
    string ext = "." + fileNameSplit[fileNameSplit.Count() - 1];
    string prefix = fileName.Substring(0, fileName.Length - ext.Length);
    while (File.Exists(saveTo+ fileName))
    {
        fileName = prefix + "[" + count.ToString() + "]" + ext;
        count++;
    }
    fu.SaveAs(saveTo + fileName);
    return new FileInfo(saveTo + fileName);
}

[/code]

 

This has proved to be very useful in developing a Trouble Ticket System, where files are often updated and saved, but we do not want to lose the older records. This could be easily modified to take a Stream input and save it as well if you are not working directly with a FileUpload control.

Record Search with LINQ: searching just got a lot easier!

A suprisingly simple search technique that will work for SQL tables, XML files, DataTables, etc.

Linq is just awesome.  I was recently asked a question on how to search through a data file with linq.  At first it seemed difficult, but after some though and fighting my way through the strange quirks, I realized how much easier Linq could [once again] make my life.

 

Here is how it's done (this article uses XML, but I have done the same exact thing with both SQL and DataTables, the concept is the same.)

 

The original question stirred from how to search through a bunch of recipes.  Each recipe (XML elements bolded) has a name, type (chicken, vegetable, etc.), calories that it contained, the amount of people that the recipe serves, and the instructions on how to make it.  Here is the dummy XML:


<?xml version="1.0" encoding="utf-8" ?>
<recipes>
    <recipe>
        <name>Hamburger</name>
        <serves>1</serves>
        <calories>500</calories>
        <type>Beef</type>
        <instructions>throw some crap together and cook it</instructions>
    </recipe>
    <recipe>
        <name>Chicken Nuggets</name>
        <serves>4</serves>
        <calories>400</calories>
        <type>Chicken</type>
        <instructions>throw some crap together and cook it</instructions>
    </recipe>
    <recipe>
        <name>Lasagna</name>
        <serves>8</serves>
        <calories>800</calories>
        <type>Pasta</type>
        <instructions>throw some crap together and cook it</instructions>
    </recipe>
    <recipe>
        <name>Ribeye</name>
        <serves>1</serves>
        <calories>600</calories>
        <type>Beef</type>
        <instructions>throw some crap together and cook it</instructions>
    </recipe>
    <recipe>
        <name>Drumsticks</name>
        <serves>3</serves>
        <calories>700</calories>
        <type>Chicken</type>
        <instructions>throw some crap together and cook it</instructions>
    </recipe>
    <recipe>
        <name>Beef Kabobs</name>
        <serves>4</serves>
        <calories>350</calories>
        <type>Beef</type>
        <instructions>throw some crap together and cook it</instructions>
    </recipe>
    <recipe>
        <name>Green Beans</name>
        <serves>5</serves>
        <calories>50</calories>
        <type>Vegetables</type>
        <instructions>throw some crap together and cook it</instructions>
    </recipe>
</recipes>

 

Now that we know our data structure, we can figure outhow to set up this search.  I am going to show a few different approaches so you can pick and choose which ones to use.  I am going to cover keyword search, number range search and specific text search.

 

First we have name search.  For that I am going to look for keywords.  I will allow users to enter none or as many as they want (to be more specific) into a TextBox.  These will be delimited with the standard space( ), comma(,) and semicolon(;).

 

Next there is type and serves which I am going to set to DropDownLists.  I am going to do this because not all numbers/words will be supported, I feel it is best to guide the user along with this and only supply available search possibilities, with 'any' always being the first option.

 

Finally there is the calories range.   For this, I will use two TextBoxes that will take in numbers of course; a minimum and a maximum.

 

Here is what the search interface looks like:

 

Here is the markup:

 

<fieldset>
    <legend>Search Recipes</legend>
    <ul>
        <li>
            <label for="name">Name</label>
            <asp:TextBox runat="server" ID="txtName" />
        </li>
        <li>
            <label for="type">Type</label>
            <asp:DropDownList ID="ddlType" runat="server" />
        </li>
       
        <li>
            <label for="serves">Serves:</label>
            <asp:DropDownList ID="ddlServes" runat="server" />
        </li>

        <li>
            <label for="calories">Calories</label>
            <asp:TextBox ID="txtCalMin" runat="server" Columns="3" />
            <span style="float:left"> to </span>
            <asp:TextBox ID="txtCalMax" runat="server" Columns="3" />
        </li>

        <li>
            <asp:Button ID="btnSearch" runat="server" Text="Search"
                onclick="btnSearch_Click" />
        </li>
    </ul>
</fieldset>

 

Now with that out of the way, we can start with the code.  First a global XElement x; and IEnumerable<XElement> filteredResults; has to be declared, x will be used within the program and initialized on Page_Load, filteredResults will be explained later.  After that is initialized, on a fresh page load (!IsPostBack)the DropDownLists must be populated:

 

protected void Page_Load(object sender, EventArgs e)
{
    x = XElement.Load(Server.MapPath(".") + "\\App_Data\\recipes.xml");
    if(!IsPostBack)
    {
        // get all of your different food 'types' and put them in the ddl
        ddlType.Items.Add("any");
        foreach(string s in ((from p in x.Descendants("type") orderby p.Value select p.Value).Distinct()))
            ddlType.Items.Add(s);
        ddlServes.Items.Add("any");
        foreach (string s in (from p in x.Descendants("serves") orderby p.Value select p.Value).Distinct())
            ddlServes.Items.Add(s);
    }
}

 

Now that the form is all ready,it is time to delve in to the actualy search.  Now keep in mind, the Linq syntax will be a bit differen, but the methods are teh EXACT same when you are working with another data type (SQL, DataTable, etc.)  After a lot of deliberation on how to do this, I decided to split it up in to two seperate parts.  First filter the elements using all the filters EXCEPT the keywords (name), then apply the keyword search.  The reason I am doing it this way is because that search could include zero terms, or 5,000; therefore iteration makes the least amount of work.  Also, for ease of use, the search will workregardless of what a user enters.  By default, the search will return everything, then narrow it down as users select more criteria.  For this I will make it so the default min/max calories are 0/9999 respectively (I will ignore any input that isn't integers) and make sure to ignore the type and  serves if 'any' is selected.  Here is the code for search, I will explain it afterwards:

 

protected void btnSearch_Click(object sender, EventArgs e)
{
    try
    {
        string[] searchTerms = txtName.Text.Split(new string[] {" ", ",", ";"}, StringSplitOptions.RemoveEmptyEntries); //gets all your search terms
        int calMin = 0;
        int calMax = 9999;
        try { calMin = int.Parse(txtCalMin.Text); }catch { }
        try { calMax = int.Parse(txtCalMax.Text); }catch { }
        if (calMin > calMax) Response.Write("<h2 style=\"color:red;\">Error: Calories<div style=\"font-size:.5em;\">Minimum can not be larger than maximum</div></h2>");
      
        var searchResults = from p in x.Descendants("recipe") // filters everything by all of the fields except Name
                        where
                            (ddlType.SelectedIndex == 0 ? true : p.Element("type").Value.Equals(ddlType.SelectedValue.ToString())) &&
                            (ddlServes.SelectedIndex == 0 ? true : p.Element("serves").Value.Equals(ddlServes.SelectedValue)) &&
                            (int.Parse(p.Element("calories").Value) >= calMin) &&
                            (int.Parse(p.Element("calories").Value) <= calMax)
                    select p;

        foreach (string s in searchTerms) // since name can be multiple words, this iterates through them all, making sure that all of the terms are present
            searchResults = from p in searchResults where p.Element("name").Value.ToLower().Contains(s.ToLower()) select p;

        if (searchResults.Count() > 0)
        {
            // output your results
            foreach (XElement xe in searchResults)
                pnlOutput.Controls.Add(new LiteralControl("<a href=\"#" + xe.Element("name").Value + "\"><div><h3>" + xe.Element("name").Value + "</h3> Calories: " + xe.Element("calories").Value + "</div></a>"));
        }
        else
            pnlOutput.Controls.Add(new LiteralControl("No Entries match your search criteria"));
    }
    catch (Exception ex)
    {
        pnlOutput.Controls.Add(new LiteralControl("<h3>Error</h3>"+ex.Message));
    }
    pnlOutput.Visible = true;
}

 

First off, you can see that the searchTerms are made by splitting the input into an array, pretty simple.  Next the min/max calories are set to defaults and attempted to be changed to the inputs, and will only be changed if there are valid inputs; it will output an error if minCal > maxCal.

 

The first leg of the search is pretty simple just return all descendants in the XML file of type recipe that follow the searhc criteria.  First I check the type, if the DropDownList is at SelectedIndex of 0 (which is the 'any' selection) I will return all, otherwise, jsut the ones that equal the selected type; I do the exact same for serves.  Then a simple check that returns those that calMin >= calories <=calMax.

 

That was not the part that confused me, it was how to get a dynamic number of search terms to be iterated through.  But this is where I cam up with the simplest of solutions.  Just search EACH term alone, and interate through it with Linq and a foreach... the beauty of the IEnumerable.  For each search term in searchTerms I simply run a new Linq statement that checks if the ameElement.Contains(that_search_term).  Therefore, every time this runs through, it will drop all entries that don't contain the term, each iteration [likely] returning fewer entries -- so simple!  But not really, for some reason (still not completely sure why), if I simply run:

 

foreach (string s in searchTerms)
    searchResults = from p in searchResults where p.Element("name").Value.ToLower().Contains(s.ToLower()) select p;

 

Does NOT work, it really only honors the last term; it is not overwriting searchResults every iteration.  After some testing, I had found out that I had to make a new variable (that's the filteredResult that we declared above) that would instead take place of searchResults and then we can write over it.  But also, you may not do this inside the foreach loop itself, as that still only honors the last term.  BUT, if the method is taken out and placed seperately, the overwrite seems to work.  But NOT for searchResults, I have to use filteredResults.  If anyone understnad exactly why this extra step is necessary, pleae enlighten me!  Here is how it is called:

 

filteredResults = searchResults;
foreach (string s in searchTerms) // since name can be multiple words, this iterates through them all, making sure that all of the terms are present
    filteredResults = iterateThroughSearchTerm(s);

 

And here is the method:

 

protected IEnumerable<XElement> iterateThroughSearchTerm(string term)
{
    return (from p in filteredResults where p.Element("name").Value.ToLower().Contains(term.ToLower()) select p);
}

 

All that is left is to simply output your findings, an error message or a 'sorry, nothing found' message.  And there you go, a bunch of different search approaches all covered at once.  Here is some example code to get you started.

 

 





 

Cascading DropDowns with SQL

an improved cascade class that includes methods using both xml and sql

I posted an entry of how to make cascading ddls with xml in the past, now I extended the class to include sql.  In this case, one of the few times I may say so I decided not to use LINQ as in this case it actually seemed to make more work.  The idea is basically the samejust usingan SQL database.  This is what the info in my DB looks like:

 

dropDowns

idcategoryitem
1 ford mustang
2 ford f-150
3 ford focus
4 chevy impala
5 chevy corvette
6 chevy blazer

 

Now I just have to make my ddls, notice the second one is empty:

 

<asp:DropDownList ID="ddlMake" runat="server" AutoPostBack="true"   onselectedindexchanged="ddlMake_SelectedIndexChanged"
    cascadeTo="ddlModel"  cascadeBlank="- select make -" >
    <asp:ListItem>- select make -</asp:ListItem>
    <asp:ListItem>ford</asp:ListItem>
    <asp:ListItem>chevy</asp:ListItem>
</asp:DropDownList>
<asp:DropDownList ID="ddlModel" Enabled="false" runat="server">
    <asp:ListItem>- select make -</asp:ListItem>
</asp:DropDownList>

 

Also notice that the attributes cascadeTo and cascadeBlank are set.   cascadeTo is the ddl you are going to cascade to, and cascadeBlank is what the empty value of the  cascaded-to ddl will be if the original is returned to index 0 (that is much easier to demonstrate than explain).

 

Now just call it in the code-behind (don't forget to put the class in your App_Code folder):

 

[code:c#]

protected void ddlMake_SelectedIndexChanged(object sender, EventArgs e)
{
    DropDownList dll = (DropDownList)sender;
    string connString = ConfigurationManager.ConnectionStrings[ "mytestDB" ].ConnectionString;
    cascade2.fromThisDropDownSql(this.Page, (DropDownList)sender, connString, "item", "category", "dropDowns" );
}

[/code]

 

This takes more inputs than the xml one, but is quite simple if you compare it to the database above.  The first two variables will always be the same, and the next 4 are simply the connection string, the table column you wish to populate the cascaded ddl with, the table column that you are filtering with, and the table name.  Doesn't really matter how your tables are layed out or where everything is located, you just change your inputs accordingly.  Really that is all that it takes.