Archive for September, 2013

Kendo UI Grid: Custom Edit Button for Ajax Grid

September 21st, 2013

While trying to display a list of data in a Kendo UI grid for which the data was loaded via Ajax, I wanted to have a custom command that loaded a new page to edit a row. In the specific case I was looking at, I didn’t want to edit inline or edit the row data in a popup dialog – I wanted to leave the page showing the grid and load a new HTML page to do the edit.

The project I was working on used ASP.NET MVC and the handy Kendo UI MVC wrappers. The key to loading a new page was inserting a clickable link that could call a controller action and pass in the ID of the row to edit. To keep things consistent, I also wanted my link to look like a normal Kendo UI grid edit button.

While I could find examples of how to include custom links when a Kendo Grid was server bound, finding out how to do the same things for an Ajax bound grid was more difficult. In the end I found that specifying a column template like this worked:

columns.Bound(invoice => invoice.ID)
          ("<span class='k-icon k-edit'></span>Edit",
           new { ID = "#=ID#" },
           new { @class = "k-button k-button-icontext" }).ToHtmlString());

Note that the first argument to the Html.ActionLink call is usually used to give the text of the link but I also included a span in order to add the correct Kendo CSS classes to make the link look like a button with an edit icon.

The result of the above client template for a column in a Kendo grid is that an edit button like the following is displayed:


and when the button is pressed, the following controller action is called:


assuming that the controller for the grid is the Invoices controller and that the row ID (or primary key of the record for the row) is 3.

Entity Framework Error: OriginalValues cannot be used for entities in the Added state

September 19th, 2013

When saving new entries to a SQL Server database using the Entity Framework, I came across the following exception error:

OriginalValues cannot be used for entities in the Added state

There may be a number of reasons why the exception was raised but I found that in my case I had to check the data I was trying to save to make sure that values were specified for all the fields and that the fields were in the ranges required by the SQL Server database.

Here is a list of the checks I had to implement before writing the data to the database using Entity Framework:-

1. Check that a value required in the SQL database didn’t have a null value, e.g. make sure a string field had an empty value “” rather than null.

2. Check that string values weren’t too long to fit, e.g. check that if the database field had a max length of 40 characters I wasn’t trying to save more characters than would fit.

3. Check that any DateTime fields were not out of range for the SQL DateTime fields. .Net DateTime defaults have the value 1/1/1 but SQL dates have a different range to .Net and cannot accept values of 1/1/1.

For each DateTime field I called this function to check (and force) the fields into a range the SQL database would accept.

public static DateTime Default(DateTime Value)
   if (Value == null)
      return DateTime.Today;
      // Check the .Net value is in a valid range for a SQL DateTime.
      if (Value < SqlDateTime.MinValue.Value || Value > SqlDateTime.MaxValue.Value)
         Value = DateTime.Today;
      return Value;