IronPython - Dynamically creating objects and binding them to a form
Coding is fun and all, but what if we could generate a form instantly without having to create sql statements or create classes? Sure, LINQ does that, but it's annoying to have to recreate the LINQ-TO-SQL file every time the database schema changes. Since IronPython is a dynamic
language, it has the ability to add new members to a type at runtime.
I've created two classes. One creates an object on the fly from the table
schema. The second one binds the object to the controls on the page, based off
the article Using Reflection to Bind Business Objects to ASP.NET Form Controls.
Fortunately, there is no need to use reflection in Python, making it quicker
than its C# counterpart.
First, let's create a simple form from the Purchasing.Vendor table.
<color:blue; "><asp:Label ID="uxMessage" runat="server" />
<asp:Panel ID="Panel1" runat="server">
<table>
<tr>
<th>
Account Number
</th>
<td>
<asp:TextBox ID="uxAccountNumber" runat="server" />
</td>
</tr>
<tr>
<th>
Name
</th>
<td>
<asp:TextBox ID="uxName" runat="server" />
</td>
</tr>
<tr>
<th>
Credit Rating
</th>
<td>
<asp:TextBox ID="uxCreditRating" runat="server" />
</td>
</tr>
<tr>
<th>
Preferred Vendor Status
</th>
<td>
<asp:RadioButtonList ID="uxPreferredVendorStatus" runat="server" RepeatDirection="Horizontal" RepeatLayout="Flow">
<asp:ListItem Value="True">Yes</asp:ListItem>
<asp:ListItem Value="False">Yes</asp:ListItem>
</asp:RadioButtonList>
</td>
</tr>
<tr>
<th>
Active Flag
</th>
<td>
<asp:RadioButtonList ID="uxActiveFlag" runat="server" RepeatDirection="Horizontal" RepeatLayout="Flow">
<asp:ListItem Value="True">Yes</asp:ListItem>
<asp:ListItem Value="False">Yes</asp:ListItem>
</asp:RadioButtonList>
</td>
</tr>
<tr>
<th>
</tholor:#A31515; ">th>
<td>
<asp:TextBox ID="uxPurchasingWebServiceURL" runat="server" />
</td>
</tr>
</table>
<br />
<asp:Button ID="btnSubmit" Text="Submit" runat="server" OnClick="btnSubmit_Click" />
</asp:Panel>
Next, for the code-behind, I've added to references to the DBObject and Formbinder classes.
import clr
clr.AddReference('System.Data')
clr.AddReference('System.Configuration')
clr.AddReference('System.Web')
from System import *
from System.Data import *
from System.Configuration import *
from System.Web import *
from System.Web.Security import *
from System.Web.UI import *
from System.Web.UI.WebControls import *
from System.Web.UI.WebControls.WebParts import *
from System.Web.UI.HtmlControls import *
from DBObject import *
from FormBinder import *
id = 8
def Page_Load(sender, e):
if not sender.IsPostBack:
Form.DataBind()
obj = DBObject("Purchasing.Vendor", id) # Get record from database
FormBinder.BindObjectToControls(obj, Panel1, "ux") # Populate form controls from record
def btnSubmit_Click(sender, e):
obj = DBObject("Purchasing.Vendor", id)
obj.ModifiedDate = DateTime.Now
FormBinder.BindControlsToObject(obj, Panel1, "ux")
obj.Update()
uxMessage.Text = "Record has been updated!"
In the Page_Load method, there are three lines. The Form.DataBind method is called to bind all the datasources before we populate them.
In the next line, a new object is created from the Purchasing.Vendor table. The
id of the record is passed
in the constructor and the object will be created with all the properties and
data from the table. The BindObjectsToControls method will go through all the
properties of the object we created, and bind the values to the controls on the
page that have the corresponding id. I prefix my controls with "ux", so I've
added that as the third parameter. Simple form binding in only three lines. I've used the
id of "8" in this scenario. In a live form, you will probably want to use a querystring variable.
Now to update the record, create the object again. As you can see in the
second line of the btnSubmit_Click method, I've set the ModifiedDate to the
current time, demonstrating that the property has been
created and can be used. I then call the BindControlsToObject method to get the
data from the form and update the object. The Update method will update the data
in the database.
The source code can be downloaded below. As you can see, quick form binding with
no need to worry about updating class files when the schema changes are writing
crud methods. You can inherit the DBObject class to extend its functionality.
IronPython Dynamic Data Access.zip (800.80 kb)