KendoUI : TypeError: n.slice is not a function

common error in Kendo UI that has a simple solution

The error:
TypeError: n.slice is not a function

Is not very clear, but it is pretty simple. You are generally using some sort of AutoComplete, DataGrid, etc. This simply means that you are not returning a collection (JSON), but a layer (or more) up from that collection you want to include. For example, you would be returning this JSON:
{
    "TrackingModels":[
        {"Id":17,"Name":"Bill"},
        {"Id":17,"Name":"Bob"}
    ]
}

When what Kendo is expecting is just this:
{[
    {"Id":17,"Name":"Bill"},
    {"Id":17,"Name":"Bob"}
]}

Inline AJAX DropDown and Text Editing with Asp.Net MVC and jQuery

including how to use a database to populate the dropdown

First thing is first, you will need to download jQuery and the Jeditable plugin (I prefer to refer to it as the Jedi-Table!). Be sure to put these references in your View (or Masterpage). Next, you have to set up a view on which to use an inline edit. I find that I often want to use this approach on tables of information. For this View, I will set it to use an IEnumerable of an Item I have called 'ItemOwner' (this is arbitrary and does not really matter). It will be a simple table that lists the Name and the Country of the owner, both of which will be editable inline. Here is the Index in my ExampleController.cs:
myDataContext db = new myDataContext();
public ActionResult Index()
{
    // get the info for the 'Countries' dropdown:
    ViewData["countries"] = db.Countries
        .Select(x => new SelectListItem() 
        { 
            Text = x.Name, 
            Value = x.Id.ToString() 
        }).ToJson();

    // get the 'ItemOwners' I am interested in:
    var owners = db.ItemOwners.Take(3);

    return View(owners);
}

As you can see there, I am also pulling the countries from the database and throwing them into the ViewState - we will get to this later. Since the Country is actually a foreign key relation, the value is set to an integer which is the identity field in the database. It is also using a .ToJson() extension which takes a IEnumerable<SelectListItem> and puts it into a simple JSON string that I use which is here:
public static string 
    ToJson(this IEnumerable<SelectListItem> slis)
{
    string output = "{";
    if (slis != null)
    {
        for (int i = 0; i < slis.Count(); i++)
        {    
            output += " '" + slis.Skip(i)
            .First().Value + "': '" + 
            slis.Skip(i).First().Text + "'" + 
            (i == slis.Count() - 1 ? " " : ",");
        }
    }
    return output += "}";
}

There is probably a better way to do that... but I don't know it?!

I am also pulling 3 ItemOwners from the database, I know this is silly, but it just an example. Here is how I am displaying them in the view:
<table>
    <thead>
        <tr>
            <th>Name</th>
            <th>Country</th>
        </tr>
    </thead>
    <tbody>
        <% foreach(var owner in Model) { %>
        <tr>
            <td><%= owner.Name %></td>
            <td><%= owner.Country.Abbreviation %></td>
        </tr>
        <% } %>
    </tbody>
</table>

Now that there is a simple table we want to make it a bit more interactive. Since we aregoing to make all of these fields editable, we need to add in a way to distinguish exactly what they are. To do that, we will need two things: the id of the item they are editing, and the type of inline editing we will be doing (i.e. dropdown or text input). So to do that, let's add in a few css classes and an identifieng ID:
<td id="name<%= owner.Id %>" class="editable text">
    <%= owner.Name %></td>
<td id="ctry<%= owner.Id %>" class="editable dropdown">
    <%= owner.Country.Abbreviation %></td>

And now add a little css to make them appear to be clickable:
td.editable:hover 
{ cursor:pointer; background-color:Orange; }

Now they all look like you can click on them, so we can move on to making the click actually do something.

This is where the jQuery comes in, and it is very simple. I have made these 'helper' methods in Javascript to make all of my inline calls centrally controllable, I keep this in my sites script folder so if I change one inline edit, I change them all; it also makes for more readable Javascript on each page.
function InlineDropdown(collectionToDropDown, ajaxAddress, dropDownDataSet) {
    collectionToDropDown.editable(ajaxAddress,
    {
        data: dropDownDataSet,
        type: 'select',
        indicator: 'saving...',
        tooltip: 'click to edit...',
        submit: 'Save',
        style: 'inherit',
        placeholder: 'click to edit'
    });
}

function InlineTextbox(collectionToInline, ajaxAddress) {
    collectionToInline.editable(ajaxAddress, 
    {
        indicator: 'saving...',
        tooltip: 'click to edit...',
        style: 'inherit',
        placeholder: 'click to edit'
    });
}

function InlineTextarea(collectionToInline, ajaxAddress) {
    collectionToInline.editable(ajaxAddress, 
    {
        type        : 'textarea',
        rows        : 4,
        indicator   : 'saving...',
        tooltip     : 'click to edit...',
        style       : 'inherit',
        submit      : 'Save',
        onblur      : 'ignore',
        placeholder : 'click to edit'
    });
}

Obviously you can read all about the options on the Jeditable page, but this is how I set them. Also notice I have a InineTextarea included as well for a textarea which is not covered here but works the exact same.

Now the jQuery calls are almost trivial:
InlineTextbox(
    $('td.editable.text'), 
    "<%= Url.Content("~/Ajax/ItemOwner.ashx") %>"
);

InlineDropdown(
    $('td.editable.dropdown'), 
    "<%= Url.Content("~/Ajax/ItemOwner.ashx") %>", 
    <%= ViewData["countries"].ToString() %>
);

What that is doing is sending the POST requests to the specified address. The POST contains a few things:
  • id - the id of the element that sent the request
  • value - the new value passed by the element
We are also passing more information there - remember that we passed both the type of field to edit and the id of the ItemOwner to edit, ie [name837] which emans we want to edit the Name field of ItemOwner 837. So we simply set up an ashx handler (which we specified above) to do the dirty work:
public void ProcessRequest(HttpContext context)
{
    string newValue;
    try
    {
        myDataContext db = new myDataContext();
        string elementId = context.Request.Form["id"];

        // since we made the first 4 of the id the 'field' whic to edit
        // we can just pull the first 4 letters for use in our switch:
        string fieldToEdit = elementId.Substring(0, 4);

        //now take anything after those 4 and it is the Id:
        int idToEdit = Convert.ToInt32(elementId.Remove(0, 4));

        // the value is simply a string:
        newValue = context.Request.Form["value"].Trim();

        // now that we have the id, get the ItemOwner from the db
        ItemOwner owner = db.ItemOwners.FirstOrDefault(x => x.Id == idToEdit);

        // after all is said and done, we will return newValue to the user so the field
        // looks as if the change has taken place (which it has)

        // using the field we pulled above, decide what to do:
        switch (fieldToEdit)
        {
            // name is easy
            case "name": owner.Name = newValue; break;

            // since the country is an integer foreign key, we need to Convert.ToInt32:
            case "ctry":
                owner.CountryId = Convert.ToInt32(newValue);
                // now that we have recorded the value, we want to return the text to
                // the user and not the id value which would make no sense
                newValue = db.Countries.FirstOrDefault(x => x.Id == owner.CountryId).Abbreviation;
                break;
            // if it wasn't caught, something is wrong:
            default: throw new Exception("invalid fieldToEdit passed");
        }

        db.SubmitChanges(); // save it
    }
    // now if an exceptions were reported, the user can see what happened
    // this also inform the user nothing was saved
    // you could easily make this not reported to the user and logged elsewhere
    catch (Exception ex) 
    { newValue = "Error: " + ex.Message + " [nothing written to db]"; }

    //now return what you want in the element:
    context.Response.Write(newValue);       
}

And that is all it takes.

Simple 'Ajax-like' page transitions without the page flicker

make smooth transitions between web pages

Every time you click on a link that transfers from webpage to webpage, there is a flicker as the page loads, that is no big secret. Often times people want to get rid of that so they use javascript to fake changing pages, but really just change content... which breaks browser functionality like the back button, which annoys users immensely.

There is a simple meta tag that can be added to your pages to eliminate this page flicker, but sadly it only works in IE. That said, there is no harm in adding it as other browsers will simply ignore it. It is so simple, yet so useful, not sure why I hadn't heard about it. Add this to your <head> section and watch the smooth transitions (in IE of course):

<meta http-equiv="Page-Enter" content="BlendTrans(Duration=.01)" />
<meta http-equiv="Page-Exit" content="BlendTrans(Duration=.01)" />


Here is a website that shows a lot more options to the tag (as painful as it is to link to a site with overlayed raindrops) http://www.aim-higher.net/meta-transitions.asp.

Automatically refresh your user's Session behind the scenes using jQuery and Asp.Net

Incredibly simple script will keep your user's Session alive without any worries

Now this is something that may or may not be useful to a lot of people, depending on you situation, you may want the user to elect to refresh their Session or not (like banks usually do); but this is for applications that may have a lot of idle time and users are annoyed with their Sessions dying... considering most users don't know what a Session is, but they know that the application stops working correctly.

It uses jQuery and is incredibly simple, just a few lines of code, and no screen flicker or any annoyance to the user at all; ignorance is bliss. First I include the following in the code-behind in any page you need to keep refreshed (works on masterpages as well):

code-behind
protected int timeout;
protected void Page_Load(object sender, EventArgs e)
{
    // one minute prior to timeout (milliseconds)
    timeout = (Session.Timeout * 60000) - 60000; 
}

Then add this jQuery to your script:

aspx or master
var to;
$().ready(function() {
  to = setTimeout("TimedOut()", <%= timeout %> );
});
            
function TimedOut() {
  $.post( "refresh_session.aspx", null,
    function(data) { 
      if(data == "success") {
        to = setTimeout("TimedOut()", <%= timeout %>);
      }
      else { $("#timeout").slideDown('fast'); }
    }
  );
}

Notice that the jQuery calls the $.post() function, where it calls the page refresh_session.aspx. That page does only one thing: Response.Write("success"); so if data comes back and it does not equal 'success' (something went wrong) it then stops the cycle of checking for timeout and shows my 'timeout' div that tells the user it is not a current session.

infinitely refreshing session...

Yup, it is just that easy. The code-behind gets the Session.Timeout, and subtracts one minute from it, this is when the refresh will be triggered. Inside the script, the setTimeout() call will then wait that amount of time and use the jQuery $.post() to hit the page in in turn refresh the Session; once that is done, it starts the cycle over again, so it should repeat on into infinite. And since this is all done via a jQuery ajax call, there is no evidence to the user this is even happening, no flicker or popup, nothing.

Inserting New Items Into a Table : 'REAL' AJAX with Asp.Net Series

Add a new item into the table and database and have it immediately sortable, pageable, etc without any postback

This is a continuation of my 'REAL' AJAX with Asp.Net (not Asp.Net AJAX) series posts for those of us trying to stop relying on Asp.Net 'AJAX'.

This is probably the hardest part about a full CRUD (Create, Read, Update, Delete) system, but as we have already covered 'RUD', it's time to hit the 'C'. First of all, we have to break down what will be happening, both on the client-side, and the server side, then it will be easier to dissect.
  1. User pulls up a 'New Entry' dialogue (client)
  2. User enters information and it is validated (client*)
  3. Valid information is sent to the server (client)
  4. Server attempts to add in new item (server)
  5. Server spits back status update (server)
  6. status update is displayed (client)
  7. item is added into the visible table (client)
  8. input fields are cleared and the input dialogue is hidden (client)

The * above denotes that while in this example we are doing only client-side validation, it is in your best interest to add in some server side as well (keep in mind that this example will not work without javascript, so it is not robust and does not 'gracefully' degrade).

As you can see, most of the heavy lifting here is done on the client side, with the dedicated server doing just a couple things.

set up the entry dialogue

First I am adding a couple divs which will be clicked to open the dialogue:

insert.aspx

<div class="button triggerNew">New Entry</div>


In the CSS, you can see that these will render like buttons:

demo.css
.button 
{ 
    width: 100px; 
    font-weight: bold; 
    border: outset 2px blue; 
    padding: 1px; 
    text-align: center; 
    color: Blue; 
}
.button:hover 
{ 
    border-style: inset; 
    cursor: pointer; 
    padding: 2px 0 0 2px; 
}

To go with the whole ajax feel, I am setting up the entry in a modal popup; you probably noticed the class 'triggerNew' which isn't really a css class, but it will be used to by jQuery to hook into any elements that have that class and tie them to the modal. To do that first we must include the jquery.jqModal plugin (which IMO is the best modal plugin as it is minimalist and customizable as well as easy to use) in our masterpage.
demo.master

<script type="text/javascript" src="js/jquery.jqModal.js"></script>


As for the modal popup, here is the markup:

<div class="jqmWindow" id="new">
  <h3 class="modal_header">
    <div class="working">working...</div>
    <a href="#" class="x jqmClose">X</a>
    Add New Entry
  </h3>
  <div class="pad">
    <div class="left">
      <h4>
        <asp:RequiredFieldValidator ID="rfvFirst" ControlToValidate="txtFirst" CssClass="right"
          ErrorMessage="required" runat="server" ValidationGroup="new" />
        First Name
      </h4>
      <input type="text" ID="txtFirst" runat="server" />
    </div>
    <div class="left">
      <h4>
        <asp:RequiredFieldValidator ID="rfvLasst" ControlToValidate="txtLast" CssClass="right"
          ErrorMessage="required" runat="server" ValidationGroup="new" />
        Last Name
      </h4>
      <input type="text" ID="txtLast" runat="server" />
    </div>
    <div class="left">
      <h4>
        <asp:RegularExpressionValidator ID="regAge" ControlToValidate="txtAge" CssClass="right"
          ErrorMessage="1-3 digits" runat="server" Display="dynamic" ValidationGroup="new" />
        <asp:RequiredFieldValidator ID="rfvAge" ControlToValidate="txtAge" CssClass="right"
          ErrorMessage="required" runat="server" Display="dynamic" ValidationGroup="new" />
        Age
      </h4>
      <input type="text" ID="txtAge" runat="server" />
    </div>
    <div class="summary">
      <div id="submit" class="button">Submit</div>
    </div>
  </div>
</div>


Now there is a lot going on there. First of all, I used the Asp.Net validators as we are most familiar with them, and they play nicely with jQuery. Also, I am not using asp:TextBoxes at all, I am sticking with the basic input boxes. But, because I am using the Asp.Net Validators, I still need to include runat="server" with each input that I Validate; this also means that they will get weird Asp.Net IDs and not the exact ones I assign them. All I am doing here is making sure all the fields have values, and that age is a diget with 1-3 digits (yes, someone can be 999 in this system...).

In addition, the css class 'jqmClose' class is included in a link: this will automatically be assigned to close the modal window by jqModal.

I also put an additional 'working' element in there so the user can see that dialogue while the program is running its magic.

But as it stands now, we can't even see that popup, get the validators to fire or submit any sort of data. Here comes the jQuery.

work the jQuery magic

Here is the script, it is explained in the comments:
//assign all 'triggerNew' elements to open the modal dialogue
$('#new').jqm({ trigger: false }).jqmAddTrigger($('.triggerNew'));

//attach this event to the clicking of the 'submit' div
$("#submit").click(function() {
    //will not do anything if the validators don't check out
    //Page_ClientValidate('ValidationGroup') is an Asp.Net generated function
    if (!Page_ClientValidate('new')) { return false; }
    else {
        // get the values from the textboxes into an array
        // notice that this is using .ClientID to get the strange Asp.Net ID assigned to it
        var vals = [
            $("#<%= txtFirst.ClientID %>"),
            $("#<%= txtLast.ClientID %>"),
            $("#<%= txtAge.ClientID %>")
        ];
        // do the ajax post
        $.post(
            //function is at
            "ajax_functions/insert.aspx",
            //send the values frorm the vals object
            { first: vals[0].val(), last: vals[1].val(), age: vals[2].val() },
            function(data) {
                //output the return data
                $("#report").html(data);
                // the class 'success' was sent back if it worked...
                var success = (data.toString().substring(12, 19) == "success");
                //add the new data into the table so the user can see it if it was successful
                if (success) {
                    oTable.fnAddData([
                    vals[0].val(),
                    vals[1].val(),
                    vals[2].val(),
                    '&nbsp;'
                ]);
                    //clear the textboxes
                    $(vals).each(function() { $(this).val('') });
                }
                //hide the modal now that it's done
                $('#new').jqmHide();
            }
        );
    }
});

Note that this will not allowed items added since the last postback to be deleted/edited, that is why the last cell simpy gets an '&nbsp;'. Keep in mind that it is possible, just beyond the scope of this tutorial.

Also, in a ghetto form of error reporting, I passed the css class which will either be 'error' on error, or 'success' otherwise.  We can use that to decide whether or not to post the new data into the table and to clear the inputs.  This will catch any errors that we did not already account for.

Really all that remains is the server-side part, we need to make the page that is called: "ajax_functions/insert.aspx" to handle the inputs passed.

server-side functions

Notice this time that we used a $.post() method, which sends the stated values and returns something - in this case, we are having it return a chunk of html which will tell us what happened with the server, and it will be pushed into the 'report' div. Here is our server operations:

ajax_functions/insert.aspx.cs
using System;

public partial class ajax_functions_insert : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        demoDataContext db = new demoDataContext();
        try
        {
            // get all the new values
            string first = Request.Form[0];
            string last = Request.Form[1];
            int age = Convert.ToInt32(Request.Form[2]);

            //make a new person
            person p = new person()
            {
                first_name = first,
                last_name = last,
                age = age
            };

            //insert them into the db
            db.persons.InsertOnSubmit(p);
            db.SubmitChanges();

            //if it was all successful
            Response.Write("<div class='success'>" + first + " " + last + " [" + age + "] inserted</div>");
        }
        // this will catch all the errors and output an error message if caught
        catch (Exception ex) 
        {
            Response.Write("<div class='success'>Error: " + ex.Message +"</div>");
        }
    }
}

As usual, this is the easy part. Now you have a full working CRUD system, with some pretty good error catching as such with absolutely no postbacks! Ajax is fun and can be quite useful, I hope these tutorials helped make it a little more accessible to some Asp.Net devs, I know I learned a lot making them.

« Deleting

Deleting Items From a Table : 'REAL' AJAX with Asp.Net Series

Delete an entry from the DB and remove the corresponding row from the table; plus an ajax loading indicator

This is a continuation of my 'REAL' AJAX with Asp.Net (not Asp.Net AJAX) series posts for those of us trying to stop relying on Asp.Net 'AJAX'.

GridView has an incredibly easy 'Delete' feature when used in conjunction with a DataSource, the problem is, that is requires a postback. Since we are going the ajax route, this is a no-go. Alternatively, we could wrap in in an UpdatePanel, but that is exactly what we are trying to avoid. Deleting is very easy, we use a lot of the same methods that were involved in fixing the sort on the last post and using the jQuery .ajax() method.

changes to the markup

First we have to add another column for deleting and stick a delete image in there, this is simple enough. I added unique ids to each row and each delete cell for jQuery to have something to hook on to, you could also add classes. The markup hasn't changed all too much:

delete.aspx

<asp:Repeater ID="rpt" runat="server" DataSourceID="lds">
  <HeaderTemplate>
    <table id="sort_table">
      <thead>
        <tr>
          <th>First</th><th>Last</th><th>Age</th><th></th>
        </tr>
      </thead>
      <tbody>
  </HeaderTemplate>
  <ItemTemplate>
    <tr>
      <td id="frst<%#Eval("person_id")%>" class="editable">
        <%#Eval("first_name")%>
      
</td>
      <td id="last<%#Eval("person_id")%>" class="editable">
        <%#Eval("last_name")%>
      
</td>
      <td id="age_<%#Eval("person_id")%>" class="editable">
        <%#Eval("age")%>
      
</td>
      <td style="test-align:right;" id="del_<%#Eval("person_id")%>">
        <img src="images/delete_item.png" alt="delete" />
      </td>
    </tr>
  </ItemTemplate>
  <FooterTemplate>
    </tbody></table>
  </FooterTemplate>
</asp:Repeater>
<asp:LinqDataSource ID="lds" runat="server"
  ContextTypeName="demoDataContext" TableName="persons" />


We put the id on the cell itself and not the image because it will be easier to grab with dataTables, not to mention easier to click.

now for the js

First of all, you will notice if we leave the .dataTables() call the same as before, you can now 'sort' by the last column (the delete column), that isn't right, we have to pass some parameters to our 'dataTables()' method to make sure that column gets ignored:
oTable = $("#sort_table").dataTable({
    "aoColumns": [null, null, null, { "bSortable": false}]
});

Also notice that we decided to store the resulting table in 'oTable' just like the last lesson. Remember that this is because the sortable data is not kept in the table itself, but in an associated array, which we will need later.

Now, using the same method as last time, we will grab the position of the clicked item, attempt the ajax call, but instead of changing a value, we will delete a row. Normally, deleting a row in ajax is very simple, you grab the row by the id, and do a hide() or slideUp(), etc. - but that will not totally work here. Sure it would function, but since we are using sizing and paging, they wouldn't reflect the changes: if you had 30 items in your table, and you were 'showing 10 of 30' items, and you deleted one the normal way, it would still say 'showing 10 of 30 items' when in fact, you are only now showing 9 of 29 items, and the problem then just compounds. The brilliant minds who wrote the dataTables plugin built in ways to get around this.

First thing, we get the position of the clicked item (which all have 'del_' as an id prefix) and store that:
var pos = oTable.fnGetPosition(this);

As well as the id of the cell as we need the corresponding 'person_id' that is contained there:
var del = $(this);

Then we simply call the .ajax() method in jQuery:
$.ajax({
    type: "POST",
    url: "ajax_functions/delete.aspx",
    data: "person_id=" + del.attr('id').replace('del_', ''),
    success: function() {
        $("#report").addClass("success").html("Person Deleted");
        oTable.fnDeleteRow(pos[0]);
    }
});

And that is where the magic happens. It was indicated that this was of type 'POST', the url that it is sent to (we will get to that in a moment), and the POST query that was sent (the delete cell's id, minus the 'del_' prefix). Then, on success, we simply output some feedback to the user into a new div with the id of 'report' - nothing special there. But on the next line, we use the 'oTable' that we stored earlier that has all of the sortable data, and call the included function 'fnDeleteRow' with the position that we collected earlier, and that is what deletes the row. The finished javascript looks like this:

delete.aspx
var oTable;
var aPos;
var editedCell;
$(function() {
    $("td[id^='del_']").addClass("pointer").click(function(event) {
        var pos = oTable.fnGetPosition(this);
        var del = $(this);
        $.ajax({
            type: "POST",
            url: "ajax_functions/delete.aspx",
            data: "person_id=" + del.attr('id').replace('del_', ''),
            success: function() {
                $("#report").addClass("success").html("Person Deleted");
                oTable.fnDeleteRow(pos[0]);
            }
        });
    });
    $(".editable").click(function() {
        aPos = oTable.fnGetPosition(this);
        editedCell = $(this);
    }).editInPlace({
        url: "ajax_functions/update.aspx",
        params: "ajax=yes",
        value_required: true,
        default_text: "click to edit",
        success: function() {
            var data = oTable.fnGetData(aPos[0]);
            data[aPos[1]] = editedCell.html();
        }
    });
    oTable = $("#sort_table").dataTable({
        "aoColumns": [null, null, null, { "bSortable": false}]
    });
});

backend

Lastly is the easy part, to make the backend to "ajax_functions/delete.aspx" to handle the POST.

ajax_functions/delete.aspx.cs
using System;
using System.Linq;

public partial class ajax_functions_delete : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        demoDataContext db = new demoDataContext();
        try
        {
            System.Threading.Thread.Sleep(1000);
            // get the person_id of the person being deleted
            int person_id = Convert.ToInt32(Request.Form[0]);
            db.persons.DeleteOnSubmit(db.persons.First(x => x.person_id == person_id));
            db.SubmitChanges();

            Response.Write("deleted");
        }
        // this will catch all the errors and output them to the edited field
        catch (Exception ex) { Response.Write("Error: " + ex.Message); }
    }
}

This code is pretty simple. Since we specified the POST in the ajax() call in jQuery, we knew the first element of the POST was going to be the person_id, and that is used to delete it from the DB.
*NOTE* that I used a Thread.Sleep() in there which I NEVER recommend using. it is just there to illustrate the ajax loading indicator that was implemented into the masterpage, which is covered next.

ajax loading indicator

I snuck a new div into the masterpage with the id of 'working' and bound it to all jQuery ajax events with the following js:
demo.master
$(function() {
    $("#working").bind("ajaxSend", function() {
        $(this).show();
    }).bind("ajaxComplete", function() {
        $(this).hide();
    });
});

Now any time jQuery is doing ajax, there will be a little notification so the user knows your app is not quitting on them. All other times, that div will be hidden.

Now all that we have left is the ability to add new items.

Inline editing with DB write : 'REAL' AJAX with Asp.Net Series

Writing to the database inline without a postback, simple and effective

This is a continuation of my 'REAL' AJAX with Asp.Net (not Asp.Net AJAX) series posts for those of us trying to stop relying on Asp.Net 'AJAX'.

This is the first example of ajax I am showing with a write to the DB, and this will show just how easy it really is. I am building on the last post (GridView Sorting/Paging : 'REAL' AJAX with Asp.Net Series) which will explain where/how the data and display is set up.

Also, you will notice that the CSS changed a bit, that is because this plugin has a hover property that resets the backgorund of the td, and that gave a funky interface; now this can be taken care of with some jQuery magic pretty easily, but that is outside the scope of what this is trying to show.

load all of your js

I am still using jQuery and the extension dataTables but for this lesson I am using an additional plugin: inPlace. So now our script loading looks like this (notice I moved the script refs into the masterpage in this lesson):

demo.master

<script type="text/javascript"
  src="js/jquery.js"></script>
<script type="text/javascript"
  src="js/jquery.dataTables.js"></script>
<script type="text/javascript"
  src="js/jquery.inplace.js"></script>


decide what you want to be editable

Now, since we are using our Repeater table from the last example, we just modify if ever-so-slightly to make it editable, to do that, we just add the class 'editable' (or whatever you want it to be) to each td that we want to be editable. In addition to adding a class, we are going to add meaningful ids to each of the cells, each ID will contain:
  • First 4 Letters - What field is being edited
  • Following digits - 'person_id' that is being edited

if you are unsure as to why we are doing this, keep reading, it will become clear.

inline_edit.aspx

<asp:Repeater ID="rpt" runat="server" DataSourceID="lds">
  <HeaderTemplate>
    <table id="sort_table">
      <thead>
        <tr><th>First</th><th>Last</th><th>Age</th></tr>
      </thead>
      <tbody>
  </HeaderTemplate>
  <ItemTemplate>
    <tr>
      <td id="frst<%#Eval("person_id")%>" class="editable">
        <%#Eval("first_name")%>
      
</td>
      <td id="last<%#Eval("person_id")%>" class="editable">
        <%#Eval("last_name")%>
      
</td>
      <td id="age_<%#Eval("person_id")%>" class="editable">
        <%#Eval("age")%>
      
</td>
    </tr>
  </ItemTemplate>
  <FooterTemplate>
    </tbody></table>
  </FooterTemplate>
</asp:Repeater>
<asp:LinqDataSource ID="lds" runat="server"
  ContextTypeName="demoDataContext" TableName="persons" />


make them editable

Now just add in a a little jQuery magic, and the fields will be editable:

inline_edit.aspx
$(function() {
    $("#sort_table").dataTable();
    $(".editable").editInPlace({
        url: "ajax_functions/update.aspx",
        params: "ajax=yes",
        value_required: true,
        default_text: "click to edit"
    });
});

You can look on the documentation for jquery.inplace.js for a further explanation, but what we declared there is that all items that have class 'editable' will now be editable; also, requests will get sent to 'ajax_functions/update.aspx' (which we haven't made yet) and we are requiring a value.

handling the ajax

Ok, so what is happening now, is if you click on a cell you will be able to edit it, and when you click off, or hit enter (you can edit these behaviors if you want), a POST will be sent to 'ajax_functions/update.aspx'. What is sent to the page is the following values:
  • update_value - the value you edited
  • element_id - the element id that was edited
  • original_html - value from before your edit

Now we only care about the first two in this example, but the third value could also be useful given the situation; possibly returning the old value if an error occurs? Also, it may be easier to see why we included both the field and the person_id in the ID of the <td>.

For handling, you could easily have seperate pages that only handle a certain element, i.e. ajax_functions/first_name.aspx for first_name, ajax_functions/last_name.aspx for last_name, etc. but I found that if you did it that way, you ended up writing the same code over and over - so what I did was combine it into a single update handling page. That is why I include 'what' is being updated in the id.

When you make your handling page, it is important that there is no html in it to start with - as the page text itself will be what is stuffed back into the area that you edited. This is the ENTIRE ajax_functions/update.aspx page:

ajax_functions/update.aspx

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="update.aspx.cs" Inherits=ajax_functions_update" %>


Anything we want to appear we will just dump out a Response.Write() for. Here is the handling code, I will explain afterwards:

ajax_functions/update.aspx.cs
using System;
using System.Configuration;
using System.Data.SqlClient;
using System.Linq;

public partial class ajax_functions_update : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        demoDataContext db = new demoDataContext();
        // this is unneccessary, but more efficient since there will 
        // be more than 1 db call, this uses the same connection
        SqlConnection con = new SqlConnection(
            ConfigurationManager
            .ConnectionStrings["demoConnectionString"].ConnectionString);

        try
        {
            // get the new value
            string newValue = Request.Form[0]; 
            // figure out what is being edited (remember, its the first 4 chars in the id)
            string what = Request.Form[1].Substring(0, 4);
            // get the person_id of the changing value (the remaining digits)
            int person_id = Convert.ToInt32(
                Request.Form[1].Substring(4, Request.Form[1].Length - 4));

            con.Open();
            // get the record you want to deal with
            person p = db.persons.First(x => x.person_id == person_id);

            // change the value depending on 'what' was sent
            switch (what)
            {
                case "frst": p.first_name = newValue; break;
                case "last": p.last_name = newValue; break;
                case "age_":
                    try { p.age = Convert.ToInt32(newValue); }
                    catch { throw new Exception("not an int"); }
                    break;
                default: throw new Exception("nothing saved");
            }
            db.SubmitChanges();
            con.Close();
            Response.Write(newValue);
        }
        // this will catch all the errors and output them to the edited field
        catch (Exception ex) { Response.Write("Error: " + ex.Message); }
        finally { con.Close(); }
    }
}

First off, the code simply sets the DataContext and opens a SqlConnection (it is explained why in the code). Then, we pull from the POST values from the Request. We pull 3 things from this:
  • person_id - 'person_id' that is being edited
  • what - what field is being edited
  • newValue - the new value for the update

Now is the easy part, get the 'person' to edit, run a switch on 'what' and and update it to 'newValue'. I caught all errors and output them to Response.Write() as that is all the user will be able to see. Also, whatever is written is returned so it integrated seamlessly.  What the user will see is 'Saving...' (unless you change the text or substitute an image) and when it is complete, they will see the new value in place of the old value (which is now written to the DB) as that is what was put in the Response.Write() (if there are no errors, otherwise they'll see the error message).

There you have it! A 'real' ajax inline update with asp.net, and it was as painless as can be! There are all sorts of other things you can do like apply a js function after the update has completed, add in a nice loading graphic instead of the text, etc. - fun to play around with.

Keep in mind with this, if a user (hacker) realizes how it works, they would be able to fabricate a POST to send to your page and update it how they see fit; so be sure you test, protect against that. In one of my apps that uses this. I make sure that the record being edited belongs to the user currently logged in before they can update.

Next will be deleting a row in this table with ajax.



but...

If I have 3 'people', with last names, 'a', 'b', and 'c', and edit 'b' to now be 'z', it will not sort correctly; 'z' will not be the last one in the table, it will still be 'c'. That is because the table data that does the sorting is not held within the table itself, but in an array of 'nodes'.

I left that as a seperate download because this part dives a little deeper into the relation of the sort/edit. What needs to be done is we have to go into the array that holds the nodes, and change the related data along with the represented data in the table.

how do I do that?

This one might require reading a few times, so bear with me. First you need to set the global variables we will be using:
var oTable;
var aPos;
var editedCell;

Then, you will need to store your table in memory:
oTable = $("#sort_table").dataTable();

Now you need to intercept the click in any editable field, and get the position of it in memory; also, we will store the edited cell into a variable as well:
$(".editable").click(function() {
    aPos = oTable.fnGetPosition(this);
    editedCell = $(this);
})

What is now in aPos is a 2-element array [int row_index, int cell_index]; editedCell is the cell that you just clicked. At this point we have all the necessary values to plug the data back in. So next we tack the '.editable()' on to the end of the previous 'click()' call and add a 'success' parameter that will fire on success of the edit. Here is the completed js:

inline_edit.aspx
var oTable;
var aPos;
var editedCell;
$(function() {
    $(".editable").click(function() {
        aPos = oTable.fnGetPosition(this);
        editedCell = $(this);
    }).editInPlace({
        url: "ajax_functions/update.aspx",
        params: "ajax=yes",
        value_required: true,
        default_text: "click to edit",
        success: function() {
            var data = oTable.fnGetData(aPos[0]); 
            data[aPos[1]] = editedCell.html();
        }
    });
    oTable = $("#sort_table").dataTable();
});

Now, the table will re-sort correctly, it's a little extra work, but the added benefit is worth it IMO. Here is the download with the extended functionality (it also has the next demo in it):

Shout it

GridView Sorting/Paging : 'REAL' AJAX with Asp.Net Series

Who knew this could be so easy... and FAST?

This is a continuation of my 'REAL' AJAX with Asp.Net (not Asp.Net AJAX) series posts for those of us trying to stop relying on Asp.Net 'AJAX'.

Ok, nothing too dramatic to start things off, we are going to make some tabled data sortable and pagable all without using a bit of postback. Not only that, but it is going to be incredibly easy!

First off we need the data that these demos will be working with, nothing complicated, just a simple SQL table 'person' that holds peoples' names and ages:

setup.sql
CREATE TABLE dbo.person (
person_id INT NOT NULL PRIMARY KEY IDENTITY,
first_name VARCHAR(50) NOT NULL,
last_name VARCHAR(50) NOT NULL,
age INT NOT NULL
);

Also included in the setup.sql file is some dummy data to populate it initially. We ill be using a Linq as our datasource throughout with a .dbml file named demo.dbml.

Next we need to display the data. Normally if I wanted to do paging, I would use a GridView, due to the fact is is already integrated. But that integration is sloooow, and requires a postback - we are ajax'ing here! What we are going to do will load all the data (which could be slower initially on large data sets) and use jQuery to take care of all of the lifting for us. So, it is much more efficient for us to use a Repeater. Without postbacks, all the advantages of a GridView quickly fade away. You will see how little markup you need:

sort_page.aspx

<asp:Repeater ID="rpt" runat="server" DataSourceID="lds">
  <HeaderTemplate>
    <table id="sort_table">
      <thead>
        <tr><th>First</th><th>Last</th><th>Age</th></tr>
      </thead>
      <tbody>
  </HeaderTemplate>
  <ItemTemplate>
    <tr>
      <td><%#Eval("first_name")%></td>
      <td><%#Eval("last_name")%></td>
      <td><%#Eval("age")%></td>
    </tr>
  </ItemTemplate>
  <FooterTemplate>
    </tbody></table>
  </FooterTemplate>
</asp:Repeater>
<asp:LinqDataSource ID="lds" runat="server"
  ContextTypeName="demoDataContext" TableName="persons" />


That is all the markup it takes, no code-behind. Now just call the javascript magic of the combination of jQuery and the extension dataTables:

sort_page.aspx
$(function() {
    $("#sort_table").dataTable();
});

And just like that you have a full sortable (with flipping sorting images), filterable, sizable, pageable and 'pretty' table using a simple Repeater. Now, I guess this isn't truly ajax, as nothing is truly pulled from the data store after the initial pull, but I argue that it is *relatively* because if you were to use a GridView jumping pages would cost a postback each time.

This is just the introduction here, but it is to show you how incredibly easy it is to get real, time-saving ajax and it is not as intmidating as you think. Next I will be showing you how to do inline editing of this table.

Shout it Update »

'REAL' AJAX with Asp.Net (not Asp.Net AJAX) Series : Building a complete ajax CRUD system with Asp.Net

Am I the only one who feels guilty every time I throw an 'UpdatePanel' into my code?

We all know Asp.Net AJAX is technically ajax, but it generally passes one the main advantage of using ajax in the first place.

Sure ajax is slick for user interface, but where I feel it really helps is speed. For example, if you want to edit a row in a GridView, you can easily do this using the GridView, stick it in an UpdatePanel and poof... you have an 'ajax' interface. But, and this is a huge but, the *ENTIRE* GridView was actually pulled from the DataSource, not just the row you were using. Asp.Net AJAX is a great tool, but it sort of masks (nearly) complete postbacks as being asynchronous; which is extremely convenient for quick development, but does not really help in the realm of performance.

Basically, I look at Asp.Net AJAX as a lazy way to do 'ajax' - that's in quotes as it really isn't asynchronous. So, lately, I have been making it my mission to get familiar with jQuery and integrating *real* ajax into my projects; and the speed gains are extremely noticable and quite impressive! Now jQuery is not necessary, but I am waaay to lazy and unskilled to write raw JS to do what I want, plus people have already written amazing jQuery plugins to do tons of what I want; not to mention it is probably written better than I could do anyway.

So, I am going to be posting a series of Asp.Net with 'real' ajax tutorials and examples in the coming weeks. I am going to be recreating all the functionality that you can get out of a GridView normally with edit, delete, new, sort, page etc. - a full CRUD (Create, Read, Update, Delete) system; but it will all be true ajax and very fast. Here are the topics that will be covered:
So stay tuned, I think you will be really impressed with how easy, and how much faster 'real' ajax is.

Shout it kick it on DotNetKicks.com

Making a registration system with Asp.Net and Linq-to-SQL (part 3)

Now that it's all up and working, we can make it friendlier and add some cool AJAX effects

After part 2 the system works just fine, but I wanted to take it a step further.This will be the last entry in this series, which I will follow up with a tutorial on how to retrieve passwords and log the registered users in.

what are we going to accomplish?

Like I said before, the system works, this is just the frosting on the cake, we are going to add some jquery and use the MasterPage to make this more accessible to the users.

markup

On the MasterPage, I added quite a few things, and on the registration page I added one key element:

demo.master
<h1>
  <span class="right">
    <a href="default.aspx">Home</a>
    <a href="register.aspx" class="triggerRegister">Register</a>
  </span>
  Registration Demo
</h1>

<div><asp:ContentPlaceHolder id="body" runat="server" /></div>

<div id="footer">
  <a href="default.aspx">Home</a> |
  <a href="register.aspx" class="triggerRegister">Register</a>
</div>

<div class="jqmWindow" id="register">
  <h3>
    <asp:UpdateProgress ID="uppRegister" runat="server">
      <ProgressTemplate>
        <div class="status">working...</div>
      </ProgressTemplate>
    </asp:UpdateProgress>
    <a href="#" class="x jqmClose">X</a>
    Register
  </h3>
  <cc:register ID="ccRegister" runat="server" />
</div>

register.aspx
cc:register ID="reg" runat="server" in_page="true" />

First of all, you have to realize, since the <div id="register" ... > has a CSS class of 'jqmWindow, it will not be visible when the page loads. This is because it is going to be within a modal popup window. Also, you will notice that there is a <cc:register ... > control within. That is what causes the small change to register.aspx as the attribute 'in_page' is added.What this does is elimiate errors that may occur if two or more of these controls are on a single page, so the validators only validate the controls they are pertinant to. The code is in the Utils.cs file if you would like to examine it.

I am also using an UpdatePanel within the modal so the user is able to see their feedback; if it wasn't (or something similar) used, the modal would be hidden after postback.

Also, some links with the class 'triggerRegister' are added, these will be the links that will trigger the modal popup (using jqModal) with the following JS:

demo.master
$('#register').jqm({ trigger: false }).jqmAddTrigger($('.triggerRegister'));

And just that simply we made the registration available multiple ways across the entire project! If the user has javascript turned off, it will will still work just fine as we have a 'backup' register.aspx page that will handle the request.Ahh the beauty of jQuery.


« Part 1« Part 2